Large human skeleton. How we are built: human skeleton with name of bones

When someone in a temper promises an enemy to “count the bones,” it is unlikely that his words should be taken literally. The human skeleton is a complex biological structure, and doctors and scientists were able to accurately answer the question of how many bones are in the human skeleton only as a result of centuries of research practice.

So, the human skeleton contains exactly 206 bones. Moreover, 85 of them are paired (170 in total) and 36 bones are not paired.
Paired bones - shoulder blades, collarbones, limb bones, etc. Unpaired bones are, for example, the frontal bone or the pectoral bone.

In men, bones make up 18% of the total body weight, in women - about 16%, and in newborn children - 14%. With age, the specific gravity of bones increases as dehydration occurs. bone tissue.

In general, the human skeleton consists of the skull, torso and limbs. How many bones are there in each part of the skeleton?

How many bones are there in the human skull?

The brain section of the skull consists of 8 bones: the frontal bone, two parietal bones, the occipital bone, the sphenoid bone, two temporal bones and the ethmoid bone.

Part facial section The skull includes 15 bones: two bones of the upper jaw, two bones of the palate, vomer, two zygomatic bones, two nasal bones, two lacrimal bones, two bones of the lower nasal concha, lower jaw and hyoid bone.

In addition, the human skull contains three pairs of middle ear bones: two malleus, two incus, and two stirrups.

How many bones are there in the human torso skeleton?

The largest number of bones in the body is part of the spinal column. 32-34 vertebrae it includes and of these:
Seven cervical vertebrae;
Twelve thoracic vertebrae;
Five lumbar vertebrae;
Three or five coccygeal vertebrae fused into the coccyx.
At the same time, twelve thoracic vertebrae are considered part of the chest. In addition, the rib cage of the human skeleton contains 12 pairs of ribs and one breast bone.

How many bones are there in a person's hand?

The upper limb girdle consists of two pairs of bones: 2 shoulder blades and 2 clavicle bones.
The shoulder consists of two humerus bones.
The forearm consists of two ulna and two radius bones.
The hand includes 27 pairs of bones, of which 8 pairs are in the wrist and 14 pairs of bones are in the fingers.

How many bones are there in the human lower limb skeleton?

The lower limb girdle or pelvis is formed by the sacrum and two pelvic bones. Each pelvic bone is formed from the fused iliac, ischial and pubic bones. That is, there are 7 bones in the human pelvis.

The free part of the human leg consists of the thigh, lower leg and foot. Each thigh consists of the femur and kneecap, each tibia consists of the tibia and fibula, and 26 bones make up each foot. All bones of the human lower limb skeleton (except the sacrum) are paired.

Here is a not very detailed, but quite complete answer to the question of how many bones are in the human skeleton.

The uniqueness of the human body lies in its harmonious and coordinated work, in which absolutely all organs and systems take part. The uniqueness of this process lies in the fact that a number of physiological processes occur simultaneously, each of which is assigned an independent role. In view of this, organs that perform one purpose or another are united into vital systems. For example, the digestive system provides the human body with necessary substances that come from food, the cardiovascular system is responsible for blood circulation and oxygen supply to tissues, but without the full functioning of the musculoskeletal system, a person will not be able to move normally.

Each of the systems plays a huge role in human life, and the slightest disruption of any of the organs can lead to a significant deterioration in health and affect the quality of life as a whole.

The human skeleton is a complex system consisting of bones various forms and sizes, each of which has a specific purpose.

For the full functioning of the musculoskeletal system, the system contains ligaments, joints, muscles, tendons and a number of other connections that provide a person with mobility.

In addition, the skeleton performs other functions, such as:

• protective;
• supporting;
• motor;
• hematopoietic;
• shock-absorbing

The skeleton of a newborn child includes about 270 bones, some of which fuse over time. These bones include the bones of the skull, spine and pelvis. In the skeleton of an adult there are 206 bones, but in some cases there may be 205 or 207. About a seventh of all bones belong to unpaired bones, the rest are paired.

Main feature skeletal structure human body is its division into axial and incremental. The bones that make up the axial skeleton form its base, the center of which is the spine. An equally important role in the skeletal system is played by the skull, which forms the head and serves as protection for the brain. The chest, which in addition to the protective functions of internal organs, plays an important role in respiratory processes.

In the area of ​​the axial skeleton there is a row of vital important organs, thanks to whose work a person lives. But, besides this, a person needs to remain functional and carry out some manipulations with the help of his arms and legs. They form the accessory skeleton, which includes the upper and lower limbs, as well as the places where the limbs join the axial skeleton.

Description of the human skeleton with photo

Structure of the human skull

The skull is a collection of bones that forms the frame of the head and serves to protect the brain. The bones of the medulla consist of such bones as the occipital, ethmoid, frontal, parietal, sphenoid, and temporal.

The facial part of the bone frame is characterized by the presence of the upper and lower jaws, on which the teeth, hyoid bone, as well as the zygomatic, lacrimal, nasal bones, vomer and turbinate. Almost all the bone elements of the skull are connected by sutures, except for the lower jaw, which is characterized by the presence of a sedentary joint.

Human spine

The spine is the fundamental part of the human skeleton, to which a number of other bones are attached. It is particularly flexible and durable, thanks to which a person can withstand significant physical activity.

The vertebrae that make up the spinal column are connected to each other by intervertebral discs and ligaments. They provide mobility of joints and soften pressure from physical activity. In addition to supporting and motor functions, the spine has protective features regarding the spinal cord. Many nerve endings are concentrated here, which take part between the activities of the brain and other human organs.

The spine consists of 33-34 vertebrae, which, in turn, are divided into the following sections:

1. The cervical region is the upper part of the spinal column, consisting of 7 vertebrae. Due to the atypical structure of the first two vertebrae, this area is the most mobile, which allows you to move your head in different directions.
2. Thoracic department. Ribs are attached to the 12 vertebrae of this section of the ridge. The chest they form is a kind of frame for protecting the respiratory system. Because of this, this part of the spine is characterized by inactivity.
3. Lumbar region. This part of the spine is susceptible maximum load which a person feels when walking, playing sports, as well as various body positions that require support. This explains the presence of larger vertebrae, the processes of which are directed backward. The lumbar section of the pillar is slightly curved, which allows it to withstand the pressure of the upper part of the human body.
4. Sacral section. After the lumbar region there is the sacrum, which consists of 5 fused vertebrae and forms a triangular-shaped bone. The main purpose of the sacral region is to connect the lumbar region and the pelvic bones.
5. Coccygeal department. The lower part of the spinal column is a collection of 3-5 fused vertebrae with a pyramidal shape. This department has a distribution function, as a result of which the load on the pelvic skeletal system is reduced.

Video: Structure of the human spine

The structure of the human leg

The leg, or lower limb, is a paired organ with supporting and motor functions. Since the legs are subject to enormous stress throughout a person’s life, nature has provided them with the largest bones, which are particularly strong and structured.

Anatomical structure of human legs:

1. The femur is the connection between the femur and the kneecap, which is round in shape and protects the knee joint from injury. The place where the thigh joins the pelvic bones is called the hip joint.
2. The lower leg is a part of the lower limb, consisting of two tibia bones and the patella. Small and big bone in the lower part of the legs are connected by the ankle joint.
3. The foot is a collection of many small bones that form different parts of the foot - rear, middle and front. The arch or instep of the foot belongs to the midfoot, the heel belongs to the rear, and the ball and toes are part of the forefoot.

The composition of the lower extremities is quite complex. One foot contains 26 bones, including the femur, tibia and patella - a total of 30. An equally important component of the legs are the muscles, the largest number of which are located in the thigh area. Slightly fewer muscle connections are found in the pelvic and lower leg areas. In total, the muscle mass of the lower extremities occupies ¼ of the total muscle mass body, and contains 39 muscles.

The structure of the human hand

The complex structure of the human upper limbs is due to its complex functionality.

The presence of numerous joints allows for incredibly precise movements; ligaments and tendons provide connecting functions, but muscles play the role of additional support.

Anatomical structure of the upper limb:

1. The shoulder girdle is the junction of the arm and the chest, in the upper part of which there is a subglob connected to the collarbone. The second end of the bone is connected to the scapula, which provides mobility to the shoulders. This part of the limb is the most powerful and can withstand significant loads.
2. The shoulder is a section of the limb consisting of the humerus, on both sides of which there are joints - the humerus and the elbow. The superficial, ulnar and radial nerve pathways pass through this area of ​​the arm.
3. The forearm is the upper part of the limb that connects the elbow and the wrist. The presence of 2 types of bones - radius and ulna - makes it possible to lift weights and exercise active species sports
4. The hand is connected to the forearm by the carpal joint, and consists of 27 small bones. The upper part of the limb is the wrist, consisting of 8 bones, 5 metacarpal bones and phalanges. Each finger contains 3 phalanges, except for the thumb, which contains only 2 bones.

The largest number of muscle connections are located in the forearm, which allows for motor activity of the fingers and hand. Tendons are directly involved in the development of joints, and are also the connecting link between the skeletal system and muscle tissue, giving flexibility to the hands. Skin covering limbs performs the functions of thermoregulation and protection. The sensitivity of the epidermis is provided by many nerve fibers, which are responsible for the reflex response of muscles to a particular stimulus.

Internal structure and functions of a person

Each internal human organ plays a huge role in the course of a huge number of physiological processes. The complexity and uniqueness of the work of all departments lies in the simultaneous performance of many functions on which human life depends.

brain

The human brain is one of the most unique organs, of great interest to scientists around the world. As a result of a huge amount of research, many scientists are in search of effective methods for using the brain to its full potential. Despite the incredible abilities of this organ, a person uses only a small part of its resources.

The brain occupies the cerebral part of the skull, and as it grows it takes on its shape. The average weight of brain tissue ranges from 1000 to 1800. In females, the brain weight is 100-200 g less than in the male brain. The central organ of the nervous system consists of the brain stem, cerebellum, left and right hemispheres. The cerebral cortex is a ball gray matter, which covers the surface of the brain. Inside the organ there is a white mass consisting of neuron processes, through which information reaches the neurons of the gray matter.

Among the huge number of functions vested in the central body, it is worth noting the following:

• visual;
• auditory;
• motor;
• regulation of breathing;
• motor;
• sensory;
• coordination of movements.

Video: Structure of the brain

structure of the human eye

The eye is a paired sensory organ whose functional purpose is the perception of visual information.

The full-fledged activity of this body is ensured by the coordinated work of all its components - optic nerve, eyeball, muscle tissue and eyelids. The movement of the eyeball is provided by muscles that receive impulses from the brain using the optic nerves. Ophthalmic muscle fibers are among the most mobile in the human body, and allow you to make many micromovements in just a hundredth of a second.

structure of the human ear

Despite the simplicity of the mechanism of the ear, its structure cannot be called such, since many constituent elements are involved in the process. The main feature of the auditory organ is the transformation of mechanical vibrations from the external environment into nerve impulses.

Anatomical composition of the ear:

• inner ear is a collection of semicircular tubules, membranous labyrinth and cochlea;
• the middle ear, which includes the tympanic cavity, auditory ossicles and Eustachian tube;
• the outer ear, consisting of the auditory canal and the auricle.

structure of the human throat

The throat plays one of essential functions in the body, as it promotes the movement of oxygen into the respiratory organs. Also, food enters the digestive organs through the throat, and the special structure of the organ prevents pieces of food from entering the respiratory tract. This area belongs to the upper respiratory tract, which includes the vocal cords, muscle connections, as well as blood vessels and nerve tracts.

Anatomical composition of the throat:

• larynx;
• pharynx;
• oropharynx;
• nasopharynx;
• trachea.

rib cage

The main purpose of the chest is to protect the internal organs and spinal column of a person from mechanical damage and deformations.

In the area of ​​the chest and abdominal cavity there is the diaphragm, a muscle that helps expand the pulmonary lobes.

The chest contains organs on which human life depends:

• - the heart, which ensures the functioning of the circulatory system;
• lungs, which are responsible for the supply of oxygen to human blood;
• - bronchi, which help cleanse and pass air into the respiratory system;
• thymus– responsible for the state of the immune system

Video: Chest organs

structure of the human heart

The human heart is a muscular organ independent of the brain, whose functions include blood circulation.

In addition, the heart muscle produces a hormonal substance that is responsible for normalizing fluid in tissue cells. The heart is located between the pulmonary lobes in the middle part of the chest, and its base is closer to the spine. The organ is connected to venous trunks, through which blood enters the heart and then into the arteries. The ventricles and atria of the heart, connected by septa, are separate cavities to which veins and arteries adjoin.

structure of the human lungs

The lungs are a paired organ of the human body that has contractile, gas exchange and cleansing functions. Thanks to active contraction movements, the lungs not only provide oxygen to the body tissues and remove harmful substances, but also help maintain the required level of acid-base and water balance.

The main feature of the structure of the respiratory organ is the unequal number of parts - the left lung consists of two lobes, the right - of three. The lungs are covered with a special membrane - the pleura, which forms a pleural sac that envelops the respiratory organs. The processes of gas exchange in the respiratory system occur in the alveoli, which are formations of epithelial cells and capillaries.

These include:

• liver;
• stomach;
• kidneys;
• adrenal glands;
• intestines;
• spleen;
• gallbladder.

video: abdominal organs

pelvic organs

The internal organs of the pelvis have excretory and reproductive purposes. The structure of the female body is characterized by a tight fit of all organs in a given area to each other, which guarantees their full functioning. Also, the female body differs from the male body in the presence of a uterus, the main reproductive organ, and ovaries, which are the source of the production of sex hormones. The lower part of the pelvis in both sexes contains the bladder and ureters. Males are characterized by the presence of a prostate gland and seminal vesicles, which are involved in the reproductive processes of the body.

Video: Pelvic organs in women

Video: Pelvic organs in men

One of the main properties of animal organisms is the ability to adapt to the surrounding world through movement. In the human body, as a reflection of the process of evolution, 3 types of movement are distinguished: amoeboid movement of blood cells, ciliated movement of epithelial cilia and movement with the help of muscles (as the main one). The bones that make up the skeleton of the body are driven by muscles and, together with them and joints, form the musculoskeletal system. This device moves the body, provides support, maintains its shape and position, and also performs a protective function by limiting the cavities in which the internal organs are placed.

The musculoskeletal system is divided into two parts: passive - bones and their connections and active - striated muscles.

A set of bones connected by connective, cartilage or bone tissue is called a skeleton (skeletos- dried).

The function of the skeleton is determined, on the one hand, by its participation in the functioning of the musculoskeletal system (function of levers during movement, support, protection), and on the other hand, by the biological properties of bone tissue, in particular its participation in mineral metabolism, hematopoiesis, regulation of electrolyte balance .

SKELETAL DEVELOPMENT

Most human bones undergo successive stages of development during embryogenesis: membranous, cartilaginous and osseous.

In the early stages, the skeleton of the embryo is represented by a dorsal string, or notochord, which arises from mesoderm cells and is located under the neural tube. The notochord exists during the first 2 months of intrauterine development and serves as the basis for the formation of the spine.

From the middle of the 1st month of intrauterine life, clusters of cells appear in the mesenchyme around the notochord and neural tube, which later turn into the vertebral column, replacing the notochord. Similar accumulations of mesenchyme are formed in other places, forming the primary skeleton of the embryo - a membranous model of future bones. This membranous (connective tissue) stage skeletal development.

Most bones, with the exception of the bones of the cranial vault, face and mid-clavicle, pass through another - cartilaginous stage. In this case, the membranous skeleton is replaced by cartilaginous tissue, which develops from mesenchyme in the 2nd month of intrauterine development. Cells acquire the ability to secrete an intermediate dense substance - chondrin.

At 6-7 weeks bones begin to appear - bone stage skeletal development.

The development of bone from connective tissue is called direct ossification, and such bones - primary bones. The formation of bone in place of cartilage is called indirect ossification, and the bones themselves are called secondary. In the embryo and fetus, intensive ossification occurs, and most of the newborn skeleton consists of bone tissue. In the postnatal period, the ossification process slows down and ends by 25-26 years.

Development of bone tissue. The essence of both direct and indirect ossification comes down to the formation of bone tissue from special cells - osteoblasts, derivatives of mesenchyme. Osteoblasts produce intercellular ground substance of bones, in which calcium salts are deposited in the form of hydroxyapatite crystals. In the early stages of development, bone tissue has a coarse fibrous structure; at more late stages- lamellar. This occurs as a result of the deposition of organic or inorganic matter in the form of plates located concentrically around the growing vessels and forming the primary osteons. As ossification proceeds, bone crossbars are formed - trabeculae, which limit the cells and contribute to the formation of spongy bone. Osteoblasts turn into bone cells - osteocytes, surrounded by bone matter. During the calcification process, cracks remain around osteocytes - tubules and cavities through which vessels pass, which play an important role in the nutrition of bones. The surface layers of the connective tissue model of the future bone turn into periosteum, which serves as a source of bone growth in thickness (Fig. 12-14).

Rice. 12.Human skull at the 3rd month of development:

1 - frontal bone; 2 - nasal bone; 3 - lacrimal bone; 4 - sphenoid bone; 5 - upper jaw; 6 - zygomatic bone; 7 - ventral cartilage (from the cartilaginous rudiment of the first branchial arch); 8 - lower jaw; 9 - styloid process; 10 - tympanic part of the temporal bone; 11 - scales of the temporal bone; 12, 16 - parietal bone; 13 - large wing of the sphenoid bone; 14 - visual channel; 15 - lesser wing of the sphenoid bone

Rice. 13. Bone development: a - cartilaginous stage;

b - beginning of ossification: 1 - point of ossification in the epiphysis of the bone; 2 - bone tissue in the diaphysis; 3 - ingrowth of blood vessels into the bone; 4 - forming cavity with bone marrow; 5-periosteum

Rice. 14.Skeleton of a newborn:

Along with the formation of bone tissue, opposite processes occur - destruction and resorption of bone sections, followed by the deposition of new bone tissue. The destruction of bone tissue is carried out by special cells - bone destroyers - osteoclasts. The processes of destruction of bone tissue and its replacement with new ones occur throughout the entire period of development and ensure the growth and internal restructuring of the bone, as well as changes in its external shape due to changing mechanical influences on the bone.

GENERAL OSTEOLOGY

The human skeleton consists of more than 200 bones, of which about 40 are unpaired and the rest are paired. Bones make up 1/5-1/7 of the body weight and are divided into the bones of the head - the skull, the bones of the torso and the bones of the upper and lower extremities.

Bone- an organ consisting of several tissues (bone, cartilage and connective tissue) and having its own vessels and nerves. Each bone has a specific structure, shape, and position that is unique to it.

Classification of bones

According to shape, function, structure and development, bones are divided into groups

(Fig. 15).

1.Long (tubular) bones- these are the bones of the skeleton of the free part of the limbs. They are built from a compact substance located along the periphery and an internal spongy substance. In tubular bones there is a diaphysis - middle part, containing the medullary cavity, the epiphyses - the ends and the metaphysis - the area between the epiphysis and the diaphysis.

2.Short (spongy) bones: bones of the wrist, tarsus. These bones are built of spongy substance surrounded by a thin plate of compact substance.

3.Flat Bones- bones of the cranial vault, scapula, pelvic bone. In them, the layer of spongy substance is less developed than in spongy bones.

4.Irregular (mixed) dice are built more complexly and combine the structural features of previous groups. These include

Rice. 15. Types of human bones:

1 - long (tubular) bone - brachial bone; 2 - flat bone - scapula; 3 - irregular (mixed) bone - vertebra; 4 - shorter than the first tubular bone - phalanx of the fingers

vertebrae, bones of the base of the skull. They are formed from several parts with different development and structure. In addition to the indicated groups of bones, there are

5.air bones, which contain cavities filled with air and lined with mucous membrane. These are the bones of the skull: the upper jaw, frontal, sphenoid and ethmoid bones.

The skeletal system also includes special

6.Sesamoid bones(patella, pisiform bone), located in the thickness of the tendons and helping the muscles work.

Bone relief determined by roughness, grooves, holes, channels, tubercles, processes, dimples. Roughness

and processes are places of attachment to bones of muscles and ligaments. The canals and grooves contain tendons, vessels and nerves. Pinholes on the surface of the bone are the passage of blood vessels that feed the bone.

Chemical composition of bones

The composition of the living bone of an adult human includes water (50%), organic substances (28.15%) and inorganic components (21.85%). Fat-free and dried bones contain approximately 2/3 of inorganic substances, represented mainly by calcium, phosphorus and magnesium salts. These salts form complex compounds in the bones, consisting of submicroscopic crystals of hydroxyapatite. The organic substances of bone are collagen fibers, proteins (95%), fats and carbohydrates (5%). These substances give bones firmness and elasticity. Bone contains more than 30 osteotropic microelements, organic acids, enzymes and vitamins. Features of the chemical composition of bone, the correct orientation of collagen fibers along the long axis of the bone and the peculiar arrangement of hydroxyapatite crystals provide bone tissue with mechanical strength, lightness and physiological activity. The chemical composition of bones depends on age (organic substances predominate in children, inorganic substances in old people), the general condition of the body, functional loads, etc. In a number of diseases, the chemical composition of bones changes.

Bone structure

Macroscopically, the bone consists of a peripherally located compact substance (substantia compacta) And spongy substance (substantia spongiosa)- masses of bone crossbars in the middle of the bone. These crossbars are not located randomly, but according to the lines of compression and tension that act on certain areas of the bone. Each bone has a structure that best suits the conditions in which it is located (Fig. 16).

Spongy bones and epiphyses of tubular bones are mainly built from spongy substance, and diaphyses of tubular bones are made from compact substance. The medullary cavity, located in the thickness of the tubular bone, is lined with a connective tissue membrane - endostome (endosteum).

Rice. 16. Bone structure:

1 - metaphysis; 2 - articular cartilage;

3- spongy substance of the epiphysis;

4- compact substance of the diaphysis;

5- bone marrow cavity in the diaphysis, filled with yellow bone marrow (6); 7 - periosteum

The cells of the spongy substance and the medullary cavity (in tubular bones) are filled with bone marrow. Distinguish between red and yellow bone marrow (medulla ossium rubra et flava). From 12 to 18 years of age, red bone marrow in the diaphysis is replaced by yellow.

The outside of the bone is covered with periosteum, and at the junction with the bones - with articular cartilage.

Periosteum(periosteum)- connective tissue formation, consisting in adults of two layers: internal osteogenic, containing osteoblasts, and external fibrous. The periosteum is rich in blood vessels and nerves, which continue into the thickness of the bone. The periosteum is connected to the bone by collagen fibers that penetrate the bone, as well as by vessels and nerves passing from the periosteum to the bone through nutrient canals. The periosteum is the source of bone growth in thickness and is involved in the blood supply to the bone. Due to the periosteum, the bone is restored after a fracture. With age, the structure of the periosteum changes and its bone-forming abilities weaken, so bone fractures in old age take a long time to heal.

Microscopically, bone consists of bone plates arranged in a certain order. These plates are formed by collagen fibers impregnated with the ground substance and bone cells: osteoblasts, osteoclasts and osteocytes. The plates contain thin tubules through which arteries, veins and nerves pass.

Bone plates are divided into general ones, covering the bone from the outer surface (outer plates) and from the side of the bone marrow cavity (inner plates), on osteon plates, concentrically located around blood vessels, and interstitial, located between osteons. Osteon is a structural unit of bone tissue. It is represented by 5-20 bone cylinders, inserted one into the other and limiting the central canal of the osteon. In addition to osteon channels, bones contain perforating nutritious channels, which connect osteon channels (Fig. 17).

Bone is an organ whose external and internal structure undergoes change and renewal throughout a person’s life in accordance with changing living conditions. Restructuring of bone tissue occurs as a result of interconnected processes of destruction and creation, ensuring high plasticity and reactivity of the skeleton. The processes of formation and destruction of bone substance are regulated by the nervous and endocrine systems.

Living conditions of the child, past illnesses, constitutional features his body influence the development of the skeleton. Sports and physical labor stimulate bone remodeling. Bones that experience heavy loads undergo restructuring, leading to a thickening of the compact layer.

Blood supply and innervation of bones. The blood supply to the bones comes from the arteries and branches of the arteries of the periosteum. The arterial branches penetrate through the nutrient openings in the bones and divide sequentially to the capillaries. Veins accompany arteries. The branches of the nearest nerves approach the bones, forming a nerve plexus in the periosteum. One part of the fibers of this plexus ends in the periosteum, the other, accompanying the blood

Rice. 17. Bone microstructure:

1 - periosteum (of two layers); 2 - compact substance consisting of osteons; 3 - spongy substance from crossbars (trabeculae) lined with endosteum on top of the bone; 4 - bone plates that form osteon; 5 - one of the osteons; 6 - bone cells - osteocytes; 7 - blood vessels passing inside osteons

nasal vessels, passes through the nutritional channels of osteons and reaches the bone marrow.

Questions for self-control

1.List the main functions of the skeleton.

2.What stages of human bone development during embryogenesis do you know?

3.What is perichondral and endochondral ossification? Give an example.

4.What groups are bones classified into according to shape, function, structure and development?

5.What organic and inorganic substances make up bone?

6.What connective tissue formation is the outside of the bone covered with? What is its function?

7.What is the structural unit of bone tissue? What is it represented by?

BONES OF THE TORSO

Development of the trunk bones

The bones of the trunk develop from sclerotomes - the ventromedial part of the somites. The rudiment of the body of each vertebra is formed from the halves of two adjacent sclerotomes and lies in the spaces between two adjacent myotomes. Accumulations of mesenchyme spread from the center of the vertebral body in the dorsal and ventral directions, forming the rudiments of the vertebral arches and ribs. This stage of bone development, as noted earlier, is called membranous.

The replacement of mesenchymal tissue with cartilage occurs through the formation of separate cartilaginous centers in the vertebral body, in the arch and rib rudiments. In the 4th month of intrauterine development, a cartilaginous vertebra and ribs are formed.

The anterior ends of the ribs are fused with the paired rudiments of the sternum. Subsequently, by the 9th week, they grow together according to midline, forming the sternum.

Spinal column

Spinal column(columna vertebralis) is the mechanical support of the entire body and consists of 32-34 interconnected vertebrae. It distinguishes 5 departments:

1) cervical of 7 vertebrae;

2) thoracic of 12 vertebrae;

3) lumbar of 5 vertebrae;

4) sacral of 5 fused vertebrae;

5) coccygeal of 3-5 fused vertebrae; 24 vertebrae are free - true and 8-10 - false, fused together into two bones: the sacrum and the coccyx (Fig. 18).

Each vertebra has body (corpus vertebrae), facing anteriorly; arc (arcus vertebrae), which, together with the body, limits vertebral foramen (for. vertebrale), representing in the aggregate spinal canal. The spinal canal contains the spinal cord. Processes extend from the arch: unpaired spinous process (processus spinosus) facing backward; two transverse processes (processus transversus); doubles upper And lower articular processes (processus articulares superior et inferior) have a vertical direction.

At the junction of the arch with the body there are upper and lower vertebral notches that limit the intervertebral foramina in the spinal column (forr. intervertebralia), where nerves and blood vessels pass. The vertebrae of different sections have characteristic features that allow them to be distinguished from each other. The size of the vertebrae increases from the cervical to the sacral due to a corresponding increase in load.

Cervical vertebrae(vertebrae cervicales) have a transverse hole (for. transversarium), the spinous process of the II-V vertebrae is bifurcated, the body is small, oval in shape. The openings of the transverse processes pass through the vertebral arteries and veins, supplying blood to the brain and spinal cord. At the ends of the transverse processes of the VI cervical vertebra, the anterior tubercle is called the carotid tubercle; the carotid artery can be pressed against it to stop bleeding from its branches. The spinous process of the VII cervical vertebra is longer, it can be easily palpated and is called the protruding vertebra. The I and II cervical vertebrae have a special structure.

First(C I) cervical vertebra- atlas(atlas) has anterior and posterior arches of the atlas (arcus anterior atlantis et arcus posterior atlantis), two

Rice. 18.1. Spinal column: a - side view; b - rear view

Rice. 18.2. Two upper cervical vertebrae:

a - first cervical vertebra-atlas, top view: 1 - transverse foramen on the transverse process; 2 - anterior arch of the atlas; 3 - anterior tubercle; 4 - tooth fossa;

5- lateral mass with superior articular surface (6); 7 - posterior tubercle; 8 - rear arc; 9 - groove of the vertebral artery;

b - second cervical vertebra - axial or axis, rear view: 1 - lower articular process; 2 - body of the axial vertebra; 3 - tooth; 4 - posterior articular surface; 5 - upper articular surface; 6 - transverse process with the same hole; 7 - spinous process

Rice. 18.3. Seventh cervical vertebra, dorsal view:

1 - vertebral arch; 2 - transverse process with transverse hole (3); 4 - vertebral body; 5 - upper articular surface; 6 - vertebral foramen; 7 - spinous process (the longest of the cervical vertebrae)

Rice. 18.4. Thoracic vertebra, lateral view:

1 - vertebral body; 2 - upper costal fossa; 3 - superior articular process; 4 - vertebral arch; 5 - transverse process with costal fossa (6); 7 - spinous process; 8 - lower articular process; 9 - lower costal fossa

Rice. 18.5. Lumbar vertebrae:

a - top view of the lumbar vertebra: 1 - mastoid process; 2 - superior articular process; 3 - transverse process; 4 - vertebral body; 5 - vertebral foramen; 6 - vertebral arch; 7 - spinous process;

b - lumbar vertebrae, side view: 1 - intervertebral disc connecting the vertebral bodies; 2 - superior articular process; 3 - mastoid process; 4 - lower articular process; 5 - intervertebral foramen

Rice. 18.6. Sacrum and coccyx:

a - front view: 1 - superior articular process; 2 - sacral wing; 3 - lateral part; 4 - transverse lines; 5 - sacrococcygeal joint; 6 - coccyx [coccygeal vertebrae Co I -Co IV]; 7 - apex of the sacrum; 8 - anterior sacral foramina; 9 - cape; 10 - base of the sacrum;

b - rear view: 1 - superior articular process; 2 - tuberosity of the sacrum; 3 - ear-shaped surface; 4 - lateral sacral ridge; 5 - median sacral ridge; 6 - medial sacral ridge; 7 - sacral fissure; 8 - sacral horn; 9 - sacrococcygeal joint; 10 - coccyx [coccygeal vertebrae Co I -Co IV]; 11 - coccygeal horn; 12 - posterior sacral foramina; 13 - lateral part; 14 - sacral canal

lateral masses (massa lateralis atlantis) and transverse processes with openings. The anterior tubercle stands out on the outer surface of the anterior arch (tuberculum anterius), on the inside - tooth fossa (fovea dentis). On the outer surface of the posterior arch there is a well-defined posterior tubercle. Each lateral (side) mass has articular surfaces: on the upper surface - upper, on the lower - lower.

The axial vertebra (axis) (C II) differs from other vertebrae in that its body continues into a process - a tooth (dens), having anterior and posterior articular surfaces.

Thoracic vertebrae(vertebrae thoracicae), unlike other vertebrae, they have two costal fossae on the lateral surfaces of the body - upper and lower (foveae costales superior et inferior). On each transverse process of the I-X vertebrae there is a costal fossa of the transverse process (fovea costalis processus transversis) for articulation with ribs. The exception is the I, X-XII vertebrae. On the I vertebra at the upper edge of the body there is a complete fossa, the X vertebra has only an upper semi-fossa, and the XI and XII each have one complete fossa in the middle of the body.

Lumbar vertebrae(vertebrae lumbales), the most massive, together with the sacral vertebrae, take the main load falling on the spinal column. Their articular processes are located sagittally, on the upper articular processes there are mastoid processes (processus mammilares). The spinous processes have a horizontal direction.

Sacrum, sacral vertebrae(vertebrae s acrales) in adults they fuse into one bone - sacrum (sacral vertebrae I-V)(os sacrum); (vertebrae sacralis I-V). The base of the sacrum is distinguished (basis ossis sacri), facing up, top (apex ossis sacri), downward and lateral parts (partes lalerales). The anterior surface of the sacrum is concave into the pelvic cavity, the posterior surface is convex and has a number of ridges. On the anterior pelvic surface (facies pelvica) there are 4 paired anterior sacral foramina (forr. sacralia anteriora), connected by transverse lines (lineae transversae), traces of fusion of the sacral vertebral bodies. On the dorsal (posterior) surface (facies dorsalis)- also 4 pairs of posterior sacral foramina (forr. sacralia posteriora).

There are 5 sacral ridges on the dorsal surface of the sacrum: unpaired median (crista sacralis mediana), paired medial

ny (crista sacralis medialis) and lateral (crista sacralis lateralis). They are respectively fused spinous, articular and transverse processes. In the lateral parts of the sacrum there is an auricular surface (facies auricularis) and sacral tuberosity (tuberositas ossis sacri), serving to connect to the pelvic bone. The base of the sacrum connects to the V lumbar vertebra at an angle to form a promontory, promontorium, which protrudes into the pelvic cavity.

Coccyx(os coccygis)- a small bone resulting from the fusion of 3-5 rudimentary vertebrae. The most developed is the first coccygeal vertebra, which has remnants of articular processes - coccygeal horns (cornua coccygeum), connecting to the sacral horns.

Thorax skeleton

TO chest skeleton(skeleton thoracis) include the sternum and ribs.

Sternum(sternum)- unpaired flat bone. It distinguishes between a handle (manubrium sterni), body (corpus sterni), xiphoid process (processus xiphoideus) and notches: along the upper edge of the manubrium there is an unpaired jugular notch (incisura jugularis) and paired clavicular notch (incisura clavicularis), on the lateral surfaces of the sternum - 7 costal notches (incisurae costales).

Ribs (I-XII)(costae) consist of bone and cartilaginous parts. The costal cartilage is the anterior part of the rib, which connects to the sternum at the 7 upper ribs. Distinguish true ribs(I-VII) (costae verae),false ribs(VIII-X) (costae spuriae) and freely ending in the thickness of the anterior abdominal wall oscillating ribs(XI and XII) (costae fluctuates). The head is distinguished in the bony part of the rib (caput costae). The head of the rib goes into narrow part- cervix (collum costae), and the neck - into the wide and long part of the rib bone - the body of the rib (corpus costae). At the junction of the neck and the body of the rib, the angle of the rib is formed (angulus costae). This is where the tubercle of the rib is located. (tuberculum costae) with an articular surface for connection with the transverse process of the corresponding vertebra. On the body of the ribs, there are external and internal surfaces.

On the inner surface along the lower edge there is a rib groove (sul. costae)- trace from adjacent vessels and nerves.

Some structural features have the first rib and the last 2 ribs. On the first rib, the upper and lower surfaces, inner and outer edges are distinguished. On the upper surface there is a tubercle of the anterior scalene muscle (tuberculum m. scaleni anterioris), furrow separator subclavian vein(anterior) from the furrow subclavian artery. The XI and XII ribs do not have a neck, angle, tubercle, groove, or ridge on the head.

Differences and anomalies in the structure of the trunk bones

The number of vertebrae may vary. Thus, there may be 6 cervical vertebrae due to the assimilation of VII into the I thoracic vertebrae and an increase in the number of thoracic vertebrae and ribs. Sometimes the number of thoracic vertebrae and ribs is reduced to 11. Sacralization is possible - the V lumbar vertebra grows to the sacrum and lumbarization - separation of the I sacral vertebra. There are frequent cases of vertebral arch splitting, which is possible in various parts of the spine, especially often in the lumbar (spina bifida). There is splitting of the sternum, the anterior end of the ribs and additional cervical and lumbar ribs.

Age, individual and gender differences relate to the shape and position of bones, cartilaginous layers between individual parts of the bone.

Questions for self-control

1.What parts of the spinal column do you know?

2. What are the differences between the I and II cervical vertebrae from the other vertebrae?

3.List features cervical, thoracic, lumbar vertebrae and sacrum.

4.What notches are on the sternum and what are they for?

5. How many ribs does a person have and what are their features?

6.What anomalies do you know in the structure of the bones of the body?

LIMB BONES

The structure of the bones of the upper and lower extremities has much in common. A distinction is made between the skeleton of the belt and the skeleton of the free limb, consisting of proximal, middle and distal sections.

Differences in the structure of the bones of the upper and lower extremities are due to the difference in their functions: the upper extremities are adapted to perform various and subtle movements, the lower extremities are adapted for support during movement. The bones of the lower limb are large, the girdle of the lower limb is inactive. The girdle of the upper limb is movable, the bones are smaller.

Limb bone development

The skeletal rudiments of the upper and lower extremities appear in the 4th week of intrauterine development.

All bones of the limbs go through 3 stages of development, and only the clavicles - two: membranous and osseous.

Bones of the upper limb(ossa membri superioris)

Upper limb belt

Upper limb belt (cingulum membri superioris) consists of the scapula and clavicle (Fig. 19).

Spatula(scapula)- a flat bone in which the costal (anterior) and posterior surfaces are distinguished (facies costalis (anterior) et posterior), 3 edges: medial (margo medialis), upper (margo superior) with shoulder blade (incisura scapulae) and lateral (margo lateralis); 3 corners: bottom (angulus inferior), upper (angulus superior) and lateral (angulus lateralis), glenoid (cavitas glenoidalis). The glenoid cavity is separated from the scapula by the neck (collum scapulae). The supraglenoid and subarticular tubercles are located above and below the glenoid cavity. (tuberculum supraet infraglenoidale). The coracoid process is located above the lateral angle (processus coracoideus) And acromion, continuing into the scapular spine, separating the supraspinatus and infraspinatus fossa. The costal surface of the scapula is concave and is called the subscapular fossa (fossa subscapularis).

Collarbone(clavicula)- curved tubular bone in which the body is distinguished (corpus clavicle) and 2 ends: sternal (extremitas sternalis) and acromial (extremitas acromialis). The sternal end is expanded, has an articular surface for connection with the sternum; The acromial end is flattened and connects to the acromion of the scapula.

Rice. 19. Bones of the upper limb, right, front view: 1 - clavicle; 2 - sternal end of the clavicle; 3 - shoulder blade; 4 - coracoid process of the scapula; 5 - articular cavity of the scapula; 6 - humerus;

7- coronoid fossa of the humerus;

8- medial epicondyle; 9 - block of the humerus; 10 - coronoid process; 11 - tuberosity of the ulna; 12 - elbow bone; 13 - head of the ulna; 14 - carpal bones; 15 - I-V metacarpal bones; 16 - phalanges of fingers; 17 - styloid process of the radius; 18 - radius; 19 - head of the radius; 20 - crest of the greater tubercle; 21 - intertubercular groove; 22 - greater tubercle; 23 - small tubercle; 24 - head of the humerus; 25 - acromion

Rice. 20. Humerus, right, rear view:

1 - humerus block; 2 - furrow ulnar nerve; 3 - medial epicondyle; 4 - medial edge of the humerus; 5 - body of the humerus; 6 - head of the humerus; 7 - anatomical neck; 8 - greater tubercle; 9 - surgical neck; 10 - deltoid tuberosity; 11 - groove of the radial nerve; 12 - lateral edge; 13 - fossa of the olecranon process; 14 - lateral epicondyle

Free part of the upper limb

Free upper limb (pars libera membri superioris) consists of 3 sections: proximal - shoulder (brachium), middle - forearm (antebrachium) and distal - brushes (manus). The skeleton of the shoulder is the humerus.

Brachial bone(humerus)- a long tubular bone, in which there is a body - a diaphysis and 2 ends - the proximal and distal epiphyses (Fig. 20).

The upper end of the humerus is thickened and forms the head (caput humeri), which is separated from the rest of the bone by an anatomical neck (collum anatomicum). Immediately behind the anatomical neck there are 2 tubercles - large and small (tuberculum majus et minus), continuing downwards into ridges separated by an intertubercular groove (suclus intertubercularis).

At the junction of the upper end of the humerus and the body there is a surgical neck (collum chirurgicum)(fractures often occur here), and in the middle of the body of the bone there is a deltoid tuberosity (tuberositas deltoidea).

Behind the tuberosity is the groove of the radial nerve (sul. n. radialis). Lower condyle - condyle (condylus humeri). Its lateral sections form the medial and lateral

epicondyles The groove of the ulnar nerve runs behind the medial epicondyle. (sul. n. ulnaris). At the base of the lower end of the humerus are the humerus block (trochlea humeri), for articulation with the ulna, and the head of the condyle of the humerus (capitulum humeri), for articulation with radius. Under the block on the posterior surface of the lower end of the bone is the olecranon fossa (fossa olecrani), on the anterior surface - coronal (fossa coronoidea).

Bones of the forearm. The skeleton of the forearm consists of 2 tubular bones: the ulna, located on the medial side, and the radius, located laterally (Fig. 21).

Elbow bone(ulna) in the area of ​​the proximal epiphysis it has 2 processes: the superior ulnar (olecranon) and lower coronoid (processus coronoideus), which limit the trochlear notch (incisura trochlearis). On the lateral side of the coronoid process there is a radial notch (incisura radialis), and below and behind - tuberosity (tuberositas ulnae). The distal epiphysis has a head, from the medial side of which the styloid process of the ulna extends (processus styloideus ulnae).

Rice. 21. Ulna and radial bones of the right forearm, rear view: 1 - olecranon; 2 - head of the radius; 3 - articular circumference; 4 - neck of the radius; 5 - tuberosity of the radius; 6 - radius; 7 - lateral surface; 8 - rear surface; 9 - rear edge; 10 - styloid process of the radius; 11 - styloid process of the ulna; 12 - rear surface; 13 - medial surface; 14 - rear edge; 15 - ulna; 16 - coronoid process

Radius(radius) has a head (proximal epiphysis), equipped at the top with a flat fossa for articulation with the humerus, and on the lateral surface - an articular circle for articulation with the ulna. Below the head there is a neck, below and medial of which there is a tuberosity (tuberositas radii). The distal epiphysis is thickened, on the lateral side it has a styloid process and a carpal articular surface.

Hand bones(ossa manus) include the carpal bones, metacarpal bones and phalanges of the fingers (Fig. 22).

Carpal bones(ossa carpi, ossa carpalia) consist of 8 small bones arranged in 2 rows. The proximal row includes (counting from the side thumb) scaphoid bone (os scaphoideum), semilunar (os lunatum), triangular (os triquetrum) and pisiform (os pisiforme).

The distal row includes the trapezium bone (os trapezium), trapezoidal (os trapezoideum), capitate (os capitatum) and hook-shaped (os hamatum). The carpal bones have articular surfaces to connect to each other and to adjacent bones.

Metacarpal bones(ossa metacarpi, ossa metacarpalia) consist of 5 metacarpal bones (I-V), each of which has a body, a base (proximal end) for connection with the second row of carpal bones, and a head (distal end). The articular surfaces of the bases of the II-V metacarpal bones are flat, while the I bone is saddle-shaped.

Finger bones(ossa digitorum);phalanx(phalanges). The first (I) finger has 2 phalanges - proximal and distal, the rest - 3 each: proximal, middle and distal. Each phalanx (phalanges) has a body, a proximal end - a base and a distal end - a head.

Differences in the structure of the bones of the upper limb

Individual characteristics of the clavicle are expressed in different lengths and different curvatures.

The shape and size of the scapula are also variable. Women have a thinner shoulder blade than men; in 70% of right-handers, the right shoulder blade is larger than the left. Individual differences in the humerus relate to its size, shape, and degree of torsion—the outward rotation of the lower epiphysis relative to the upper. One of the bones of the forearm, usually the radius, may be missing. Both bones can be fused along their entire length.

Rice. 22. Bones of the hand, front view:

1 - trapezium bone; 2 - trapezoid bone; 3 - scaphoid bone; 4 - lunate bone; 5 - triangular bone; 6 - pisiform bone; 7 - hamate bone; 8 - metacarpal bones; 9 - phalanges of fingers; 10 - capitate bone

Questions for self-control

1.What bones belong to the girdle of the upper limb and parts of the free upper limb?

2.Name the bones that make up the proximal and distal rows of carpal bones.

3.List the articular surfaces of the bones of the shoulder and forearm. What are they for?

Bones of the lower limb(ossa membri inferioris)

Lower limb belt

Lower limb belt (cingulum membri inferioris) represented by paired pelvic bones. In front they connect with each other, in the back - with the sacrum, forming a bone ring - the pelvis, a container for the pelvic organs and a support for the torso and lower extremities (Fig. 23).

Hip bone(os sohae)(Fig. 24) consists of 3 fused bones: ilium, pubis and ischium. Until the age of 14-17 they are connected by cartilage.

The bodies of these three bones form the acetabulum (acetabulum)- the junction with the head of the femur. The acetabulum is bounded by a margin, which is interrupted below by the notch (incisura acetabuli). Bottom - hole acetabulum (fossa acetabuli) peripherally limited by the articular lunate surface (facies lunata).

Ilium(os tlium) consists of a body (corpus ossis ili) and wing (ala ossis ilii), separated from each other on the inner surface of the bone by an arcuate line (linea arcuata). The wing of the ilium is a wide bony plate, fan-shaped, expanding upward and ending with a thickened edge - the iliac crest. (crista iliaca). Anteriorly on the crest is the superior anterior iliac spine (spina iliaca anterior superior), behind - superior posterior iliac spine (spina iliaca posterior superior).

Below the superior anterior and posterior spines are the inferior anterior iliac spine. (spina iliaca anterior inferior) and inferior posterior iliac spine (spina iliaca posterior inferior). The iliac spines are the attachment points for muscles and ligaments.

The 3 broad muscles of the anterior abdominal wall are attached to the iliac crest. The inner surface in the anterior section is concave and

Rice. 23. Bones of the lower limb, front view:

1 - sacrum; 2 - sacroiliac joint; 3 - superior branch of the pubic bone; 4 - symphyseal surface of the pubic bone; 5 - lower branch of the pubic bone; 6 - branch of the ischium; 7 - ischial tuberosity; 8 - body of the ischium; 9 - medial epicondyle of the femur; 10 - medial condyle of the tibia; 11 - tuberosity of the tibia; 12 - body of the tibia; 13 - medial malleolus; 14 - phalanges of fingers; 15 - metatarsal bones; 16 - tarsal bones; 17 - lateral malleolus; 18 - fibula; 19 - anterior edge of the tibia; 20 - head of the fibula; 21 - lateral condyle of the tibia; 22 - lateral epicondyle of the femur; 23 - patella; 24 - femur;

25 - greater trochanter of the femur;

26- neck of the femur; 27 - head of the femur; 28 - wing of the ilium; 29 - iliac crest

Rice. 24. Pelvic bone, right: a - outer surface: 1 - ilium; 2 - outer lip; 3 - intermediate line; 4 - inner lip; 5 - anterior gluteal line; 6 - superior anterior iliac spine; 7 - lower gluteal line; 8 - lower anterior iliac spine; 9 - semilunar surface; 10 - obturator ridge;

11- lower branch of the pubic bone;

12- obturator groove; 13 - acetabular notch; 14 - obturator foramen; 15 - branch of the ischium; 16 - body of the ischium; 17 - ischial tuberosity; 18 - lesser sciatic notch; 19 - ischial spine; 20 - acetabulum;

21 - greater sciatic notch;

22- posterior inferior ischial spine; 23 - posterior superior ischial spine;

b - inner surface: 1 - iliac crest; 2 - iliac fossa; 3 - arcuate line; 4 - iliac tuberosity; 5 - ear-shaped surface; 6 - greater sciatic notch; 7 - ischial spine; 8 - lesser sciatic notch; 9 - body of the ischium; 10 - branch of the ischium; 11 - obturator foramen; 12 - lower branch of the pubic bone; 13 - symphyseal surface; 14 - upper branch of the pubic bone; 15 - pubic tubercle; 16 - crest of the pubic bone; 17 - iliopubic eminence; 18 - lower anterior iliac spine; 19 - superior anterior iliac spine

forms the iliac fossa (fossa iliaca), and behind it passes into the auricular surface (facies auricularis), connecting to the corresponding surface of the sacrum. Behind the auricular surface is the iliac tuberosity (tuberositas iliaca) for attaching ligaments. On the outer surface of the ilium wing there are 3 rough gluteal lines for attachment of the gluteal muscles: lower (linea glutea inferior), front (linea glutea anterior) and back (linea glutea posterior).

At the border between the ilium and pubic bones there is an iliopubic eminence (eminentia iliopubica).

Ischium(os ischii) located inferior to the acetabulum, has a body (corpus ossis ischii) and branch (r. ossis ischi). The body participates in the formation of the acetabulum, and the ramus connects to the inferior ramus of the pubis. On the posterior edge of the body there is a bony protrusion - the ischial spine. (spina ischiadica), which separates the greater sciatic notch (incisura ischiadica major) from small (incisura ischiadica minor). At the point of transition of the body into the branch is the ischial tuberosity (tuber ischiadica).

pubic bone(os pubis) has a body (corpus ossis pubis), upper and lower branches (rr. superior et inferior os pubis). The body makes up the lateral part of the bone and participates in the formation of the acetabulum. Medially, the bone faces the corresponding bone of the opposite side and is equipped with a symphysial surface (facies symphysialis). The crest of the pubis is located on the superior surface of the superior ramus (pecten ossis pubis), which ends anteriorly and medially with the pubic tubercle (tuberculum pubicum).

Free part of the lower limb

Free lower limb (pars libera membri inferioris) consists of 3 sections: proximal - thigh, middle - lower leg and distal - foot.

The hip skeleton is femur(femur)(Fig. 25).

It is the longest tubular bone in the skeleton. It distinguishes between the body, proximal and distal epiphyses. The upper, proximal epiphysis has a head (caput femoris), connecting to the acetabulum of the pelvic bone; at the junction the head is covered with hyaline cartilage. The head of the femur contains the fossa of the femoral head. (fovea capitis femoris), which is the site of attachment of the femoral head ligament. Below the head is the neck of the femur (collum femoris).

At the border of the neck and body of the femur there are 2 protrusions - the trochanters, greater and lesser (trochanter major et minor). The greater trochanter is located laterally. The lesser trochanter is located inferior and medial. The trochanters are connected anteriorly by the intertrochanteric line (linea intertrochanterica), posteriorly - intertrochanteric ridge (crista intertrochanterica).

The body of the femur is smooth in front, there is a rough line behind (linea aspera). It distinguishes the medial lip (labium mediate), passing at the top into the intertrochanteric line, and the lateral lip (labium laterale), ending at the top with the gluteal tuberosity (tuberositas glutea). Below the lips diverge, limiting the triangular shape of the popliteal surface (facies poplitea).

The lower, distal epiphysis is expanded and represented by medial and lateral condyles (condyli medialis et lateralis). The lateral sections of the condyles have rough projections - copper-

Rice. 25. Femur, right, posterior surface:

I - fossa of the femoral head; 2 - head of the femur; 3 - neck of the femur; 4 - greater trochanter; 5 - intertrochanteric ridge; 6 - lesser trochanter; 7 - comb line; 8 - gluteal tuberosity;

9- medial lip of the linea aspera;

10- lateral lip of linea aspera;

II - body of the femur; 12 - popliteal surface; 13 - lateral epicondyle; 14 - lateral condyle; 15 - intercondylar fossa; 16 - medial condyle; 17 - medial epicondyle; 18 - adductor tubercle

al and lateral epicondyles (epicondyli medialis et lateralis). Both condyles are covered with cartilage, which in front passes from one condyle to the other, forming the patellar surface (facies patellaris), to which the patella is attached.

Patella(patella)- sesamoid bone that develops in the tendon of the quadriceps femoris muscle. It increases the leverage of this muscle and protects the knee joint at the front.

Shin bones represented by the tibia (located medially) and fibula (Fig. 26).

Tibia(tibia) has a body and expanded cones - epiphyses. The proximal epiphysis is divided into medial and lateral condyles (condyli medialis et lateralis), the upper articular surface of which is connected to the articular surface of the femoral condyles. The articular surfaces of the condyles are separated

Rice. 26. Tibia and fibula, posterior view: 1 - condylar eminence; 2 - fibular articular surface; 3 - nutrient opening; 4 - rear surface; 5 - body of the tibia; 6 - medial malleolus; 7 - ankle groove; 8 - medial edge; 9 - line of the soleus muscle; 10 - apex of the head of the fibula; 11 - head of the fibula; 12 - rear edge; 13 - rear surface; 14 - nutrient opening; 15 - lateral surface; 16 - lateral malleolus; 17 - medial ridge

intercondylar eminence (eminentia intercondylaris), in front and behind which are the intercondylar fields - the places of attachment of the ligaments. On the posteroinferior surface of the lateral condyle is the fibular articular surface (facies articularis fibularis), necessary for connection with the head of the fibula.

The distal epiphysis is quadrangular in shape and forms the medial malleolus medially (malleolus medialis), and laterally - the fibular notch (incisura fibularis) for the fibula. On the front of the body there is a tuberosity of the tibia (tuberositas tibiae)- insertion site of the quadriceps femoris tendon.

Fibula(fibula) thin, widened upward in the form of a head (caput fibulae), and below is extended into the lateral malleolus (malleolus lateralis) for connection with the talus.

Foot bones(ossa pedis)(Fig. 27) include 3 sections: tarsus, metatarsus and fingers. Tarsal bones (ossa tarsi, ossa tarsalia) include 7 spongy bones, forming 2 rows - proximal (talus and calcaneus) and distal (scaphoid, cuboid and 3 wedge-shaped).

Rice. 27. Bones of the foot, right, top view:

1 - calcaneus; 2 - talus block; 3 - talus; 4 - scaphoid bone; 5 - medial sphenoid bone; 6 - intermediate sphenoid bone; 7 - I metatarsal bone; 8 - proximal phalanx; 9 - distal (nail) phalanx; 10 - middle phalanx; 11 - tuberosity of the fifth metatarsal bone; 12 - cuboid bone; 13 - lateral sphenoid bone; 14 - tubercle of the calcaneus

Talus(talus) is the connector between the bones of the lower leg and the rest of the bones of the foot. The body is isolated in it (corpus tali), neck (collum tali) and head (caput tali). The body on top and sides has articular surfaces for articulation with the tibia bones.

Calcaneus(calcaneus) has a calcaneal tubercle (tuber calcanei).

Scaphoid(os naviculare) lies on the medial side of the foot and connects in front with the three wedge-shaped bones, and in the back with the talus.

Cuboid(os cuboideum) is located on the lateral side and connects with the IV and V metatarsal bones, at the back - with the calcaneus, and on the medial side - with the lateral sphenoid bone.

Sphenoid bones: medial, intermediate and lateral (os cuneiforme mediale, intermedium et laterale)- located between the scaphoid bone and the bases of the first 3 metatarsal bones.

Metatarsals(ossa metatarsi; ossa metatarsalia) consist of 5 (I-V) tubular bones having a base, body and head. The articular surfaces of the base are connected to the tarsal bones and to each other, the head is connected to the corresponding phalanx of the fingers.

Finger bones; phalanx(ossa digitorum; phalanges) represented by phalanges (phalanges). The first toe has 2 phalanges, the rest - 3 each. There are proximal, middle and distal phalanges. The bones of the foot are not located in one plane, but in the form of an arc, forming a longitudinal and transverse arch, which provides springy support for the lower limb. The foot rests on the ground at several points: the tubercle of the heel bone and the heads of the metatarsal bones, mainly I and V. The phalanges of the fingers only lightly touch the ground.

Differences in the structure of the bones of the lower limb

The pelvic bone has pronounced gender differences. In women, the upper branch of the pubic bone is longer than in men, the wings of the ilium and the ischial tuberosities are turned outward, and in men they are located more vertically.

The acetabulum may be underdeveloped, which causes congenital dislocation of the hip.

The femur varies in length and the degree of bending and twisting of the shaft. In old people, the bone marrow cavity of the body of the femur increases, the angle between the neck and the body decreases, the head

The bones are flattened and as a result the total length of the lower limbs is reduced.

Of the bones of the lower leg, the tibia has the greatest individual differences: its size, shape, cross-section of the diaphysis and the degree of its twist are different. Very rarely one of the leg bones is missing.

Accessory bones are found in the foot, as well as splitting of some bones; there may be additional fingers - one or two.

X-ray anatomy of the bones of the trunk and limbs

X-rays make it possible to examine the bones of a living person, evaluate their shape, size, internal structure, number and location of ossification points. Knowledge of bone x-ray anatomy helps to distinguish normal from skeletal pathology.

For X-ray examination of the vertebrae, separate images (x-rays) are taken of the cervical, thoracic, lumbar, sacral and coccygeal regions in the lateral and anteroposterior projections, and, if necessary, in other projections. On radiographs

Rice. 28. X-ray of the humerus, mediolateral (lateral) projection: 1 - clavicle; 2 - coracoid process; 3 - acromial process of the scapula; 4 - articular cavity of the scapula; 5 - head of the humerus; 6 - surgical neck of the humerus; 7 - diaphysis of the humerus; 8 - coronoid fossa of the humerus; 9 - superposition image of the head of the condyle and the trochlea of ​​the humerus; 10 - fossa of the olecranon process of the humerus; 11 - radius; 12 - ulna (according to A.Yu. Vasiliev)

of the vertebrae in the lateral projection, the bodies, arches, and spinous processes are visible (ribs are projected on the thoracic vertebrae); The transverse processes are projected (overlaid) on the bodies and pedicles of the vertebral arches. On photographs in the anteroposterior projection, one can identify the transverse processes, bodies onto which the arches and spinous processes are projected.

On radiographs of the bones of the upper and lower extremities in the anteroposterior and lateral projections, the details of their relief, as well as the internal structure (compact and spongy substance, cavities in the diaphysis), discussed in the previous sections of the textbook, are determined. If an X-ray beam sequentially passes through several bone structures, then their shadows overlap each other (Fig. 28).

It should be taken into account that in newborns and children, due to incomplete ossification, some bones may be presented in fragments. In adolescents (13-16 years old) and even youth (17-21 years old) in the epiphyses of long bones, stripes corresponding to epiphyseal cartilages are observed.

Radiographs of the skeleton, in particular the hand, which consists of many bones with different periods of ossification, serve as objects for determining the age of a person in anthropology and forensic medicine.

Questions for self-control

1.What bones belong to the girdle of the lower limb and parts of the free lower limb?

2.List the protrusions (tubercles, lines) on the bones of the lower limb that serve as the site of origin and attachment of muscles.

3.What articular surfaces of the bones of the lower limb do you know? What are they for?

4. How many bones make up the foot? What kind of bones are these?

5. In what projections are the bones of the upper and lower extremities clearly visible on radiographs?

BRIEF INFORMATION ABOUT SKULL BONES

Scull(cranium) is the skeleton of the head. It consists of two departments, different in development and functions: brain skull(neurocranium) And facial skull(viscerocranium). The first forms a cavity for

brain and some sensory organs, the second forms the initial parts of the digestive and respiratory systems.

In the brain skull there are cranial vault(calvaria) and located below base(basis cranii).

The skull is not a single monolithic bone, but is formed by various types of connections from 23 bones, some of which are paired (Fig. 29-31).

Brain bones

Occipital bone(os occipitale) unpaired, located posteriorly. It distinguishes basilar part, 2 lateral parts and scales. All these parts limit a large hole (for. magnum), through which the spinal cord connects to the brain.

Parietal bone(os parietale) the steam room, located anterior to the occipital, has the appearance of a quadrangular plate.

Frontal bone(os frontale) unpaired, placed in front of other bones. It contains 2 orbital parts, forming the upper wall of the orbit, frontal scales And bow part. Inside the bone there is a cavity - the frontal sinus (sinus frontalis).

Ethmoid bone(os ethmoidals) unpaired, located between the bones of the brain skull. Consists of a horizontally oriented cribriform plate with extending upwards from it cockscomb, going down perpendicular plate and the most massive part - lattice labyrinth, built from numerous lattice cells. Moving away from the labyrinth top And middle turbinates, and uncinate process.

Temporal bone(os temporale) steam room, the most complex structure of all the bones of the skull. It contains the structures of the outer, middle and inner ear, important vessels and nerves. There are 3 parts to the bone: scaly, pyramid (rocky) And drum On the scaly part there is zygomatic process And mandibular fossa, involved in the formation of the temporomandibular joint. In the pyramid (rocky part) there are 3 surfaces: anterior, posterior and lower, on which there are numerous holes and grooves. The holes communicate with each other through channels running inside the bone. Down they go mastoid And subulate shoots. The tympanic part, the smallest of all, is located around external auditory holes. On the back surface of the pyramid is internal auditory opening.

Rice. 29. Skull, front view:

1 - supraorbital notch/foramen; 2 - parietal bone; 3 - sphenoid bone, large wing; 4 - temporal bone; 5 - eye socket; 6 - orbital surface of the greater wing of the sphenoid bone; 7 - zygomatic bone; 8 - infraorbital foramen; 9 - pear-shaped aperture; 10 - upper jaw; 11 - teeth; 12 - chin hole; 13 - lower jaw; 14 - anterior nasal spine; 15 - opener; 16 - inferior nasal concha; 17 - middle turbinate; 18- infraorbital margin; 19 - ethmoid bone, perpendicular plate; 20 - sphenoid bone, lesser wing; 21 - nasal bone; 22 - supraorbital margin: 23 - frontal notch/foramen; 24 - frontal bone

Rice. thirty.Skull, right view:

1 - frontal bone; 2 - wedge-frontal suture; 3 - wedge-squamous suture; 4 - sphenoid bone, large wing; 5 - supraorbital notch/foramen; 6 - ethmoid bone; 7 - lacrimal bone; 8 - nasal bone; 9 - infraorbital foramen; 10 - upper jaw; 11 - lower jaw; 12 - chin hole; 13 - zygomatic bone; 14 - zygomatic arch; 15 - temporal bone, styloid process; 16 - external auditory canal; 17 - temporal bone, mastoid process; 18 - temporal bone, scaly part; 19 - lambdoid suture; 20 - occipital bone; 21 - parietal bone; 22 - scaly seam; 23 - sphenoparietal suture; 24 - coronal seam

Rice. 31. Skull, back view:

1 - external occipital protrusion; 2 - parietal bone; 3 - lambdoid suture; 4 - temporal bone, scaly part; 5 - temporal bone, pyramid, petrous part; 6 - mastoid foramen; 7 - temporal bone, mastoid process; 8 - temporal bone, styloid process; 9 - sphenoid bone, pterygoid process; 10 - incisive holes; 11 - teeth; 12 - lower jaw; 13 - upper jaw, palatine process; 14 - opening of the lower jaw; 15 - palatine bone; 16 - occipital condyle; 17 - opener; 18 - lower nuchal line; 19 - upper nuchal line; 20 - highest nuchal line; 21 - occipital area; 22 - sagittal suture

auditory ossicles, located inside the temporal bone, are discussed in the section “The doctrine of the sense organs - aesthesiology”.

Sphenoid bone(os sphenoidale) unpaired, located in the middle of the base of the skull. It has 4 parts: body and 3 pairs of shoots, of which 2 pairs are directed laterally and are called small And big wings. Third pair of processes (pterygoid) facing downwards. There is a cavity in the body (sphenoid sinus) and deepening (saddle turcica), which houses the pituitary gland. The processes have holes, grooves and channels for the passage of blood vessels and nerves.

Facial bones

Upper jaw(maxilla) the steam room is located in the center of the face and connects to all its bones. It distinguishes body and 4 process, of which frontal directed upwards alveolar- down, palatine- medially, and zygomatic - laterally. There is a large cavity in the body - maxillary sinus. There are 4 surfaces on the body: anterior, infratemporal, orbital and nasal. The frontal and zygomatic processes articulate with the bones of the same name, the palatine - with a similar process of the other upper jaw, and the alveolar contains dental alveoli, in which the teeth are placed.

Lower jaw(mandibula) unpaired This is the only movable bone of the skull. It has body and 2 branches. In the body, the base of the lower jaw and the one located above it are distinguished alveolar part, containing dental alveoli. On the outside there is chin protuberance. The branch includes 2 processes: condylar, ending head of the mandible for the formation of the temporomandibular joint, and coronary, being the site of muscle attachment.

Cheekbone(os zygomaticum) steam room, has frontal And temporal processes, connecting to the bones of the same name.

Palatine bone(os palatinum) steam room, located behind the upper jaw. Consists of 2 plates: horizontal, connecting to the palatine process of the maxilla, and perpendicular, the upper jaw adjacent to the nasal surface of the body.

Lacrimal bone(os lacrimale) steam room, located in the anterior part of the medial wall of the orbit; nasal bone(os nasale) steam room, is the anterior bone that forms the nasal cavity; opener(vomer)

unpaired bone forming the posterior part of the nasal septum; inferior turbinate(concha nasalis inferior) steam room, adjacent to the nasal surface of the body of the upper jaw.

As we study this system more deeply, we will see its protective significance, as well as its connections with all other systems of the body.

Structure and location of bones and joints

The skeletal system includes hard connective tissue that forms cartilage, ligaments, and tendons.

• Cartilage acts to connect and provide flexibility and protection.
• Ligaments connect bones to joints, allowing two or more bones to move together.
• Tendons that connect muscles to bones.

Bones

Bones are the toughest connective tissue structures. They vary greatly in size and shape, but are similar in structure, development and function. Bones consist of living, active connective tissue of the following composition:

• Water - about 25%.
• Inorganic substances - calcium and phosphorus - make up approximately 45%.
• Organic matter makes up about 30% and includes bone cells, osteoblasts, blood and nerves.

Bone Formation

Since bones are living tissue, they grow during childhood, bleed and hurt when broken, and are capable of healing on their own. As we grow older, bones harden—ossification—as a result of which the bones become very durable. Bones also contain collagen, which provides their elasticity and firmness, and calcium, which gives strength. Many bones are hollow. And inside their cavities they contain bone marrow. Red produces new blood cells, while yellow stores excess fats. Like the epidermis of the skin, bones are constantly renewed, but, unlike the upper layer of skin, this process is very slow. Special cells - osteoclasts - destroy old bone cells, and osteoblasts form new ones. When bone grows, they are called osteocytes.

There are two types of bone tissue: compact (dense) substance, or hard bone tissue, and spongy substance, or porous tissue.

Compact substance

The compact substance has an almost solid structure, it is hardy and durable.

The compact bone substance consists of several Haversian systems, each of which includes:

• The central Haversian canal contains blood and lymphatic vessels, as well as nerves that provide “nutrition” (respiration and cell division) and “sensation”.
• Bone plates called lamellae located around the Haversian canal. They form a hard, very durable structure.

Cancellous bone

Cancellous bone tissue is less dense and makes the bone look like a sponge. It has many more Haversian canals and fewer thin plates. All bones are composed of a combination of compact and spongy tissue in varying proportions, depending on their size, shape and purpose.

The bones are covered on top with periosteum or cartilage, which provides additional protection, strength and endurance.

• The periosteum covers the length of the bone.
• Cartilage covers the ends of the bones at the joint.

Periosteum

The periosteum has two layers: the inner layer produces new cells for bone growth and repair, and the outer layer contains many blood vessels that provide nutrition.

Cartilage

Cartilage is made up of tough connective tissue containing collagen and elastin fibers, which provide flexibility and endurance. There are three types of cartilage:

1. Hyaline cartilage, sometimes called articular cartilage, covers the ends of bones where they meet at joints. They prevent damage to bones when they rub against each other. They also help attach certain bones, such as the ribs, to the rib cage, and they make up some parts of the nose and trachea.
2. Fibrous cartilage is less flexible and slightly denser and makes up the cushions between bones, such as between vertebrae.
3. Elastic cartilage is very flexible and makes up parts of the body that need fairly free movement, such as the ears.

Ligaments

Ligaments are made of fibrous cartilage tissue and are tough tissue that connects bones at joints. Ligaments allow bones to move freely along a safe path. They are very dense and prevent the bones from making movements that could cause damage.

Tendons

Tendons are made up of bundles of collagen fibers that attach muscles to bones. Thus, the calcaneal (Achilles) tendon attaches the calf to the foot at the ankle. Wide and flat tendons, such as those that attach the muscles of the head to the skull, are called aponeuroses.

Types of bones

The skeleton is made up of different bones that have different locations and functions. There are five types of bones: long, short, asymmetrical, flat and sesamoid.

1. Long bones are the bones of the limbs, i.e. arms and legs. They are longer than wide.
2. Short bones are small in size. They are the same length and width, round or cuboid in shape. These include, for example, the bones of the wrists.
3. There are asymmetrical bones different forms and sizes. These include the bones of the spine.
4. Flat bones are thin and usually round, such as the shoulder blades.
5. Sesamoid bones are small, located inside tendons, such as the patella.

Long bones consist mainly of compact substance. They have cavities filled with yellow bone marrow.

Short, asymmetrical, flat and sesamoid bones are composed of a spongy substance containing red marrow, which is covered by a compact substance without marrow. Some bones, such as the face, have cavities filled with air that make them lighter.

Bone growth

Skeletal growth continues throughout life, with bone reaching its final thickness, length and shape by age 25. After this, bones continue to develop as old cells are replaced by new ones. The following factors influence bone development:

• Genes - Individual characteristics of bones, such as length and thickness, are inherited.
• Nutrition - Full bone development requires a balanced diet rich in vitamin D and minerals such as calcium. Vitamin D promotes the absorption of calcium from the digestive system, which is carried to the bones by the blood. The presence of calcium is what makes bones so strong.
• Hormones - affect the growth and development of bones. Hormones are chemical carriers of information that enter the bones with the blood. They tell the bones when to stop growing and so on.

The skeletal system is capable of self-repairing if damaged. During a fracture, the following processes occur:

1. Blood clots at the fracture site.
2. Osteoblasts form new bone tissue.
3. Osteoclasts remove old cells and direct the growth of new ones.

This process can be assisted by using splints, plaster, metal plates, screws, etc. to hold the bone in place while it heals.

Skeleton

Now that we have studied the components of the skeletal system and their connections, we can consider the skeleton as a whole. We need to learn to recognize the bones and joints of the skeleton to know how the human body holds and moves.

The human skeleton consists of two parts: the accessory and axial skeleton.

The axial skeleton consists of:

• Skulls - brain and facial.
• Spine - cervical and dorsal.
• Chest.

The accessory skeleton consists of:

• Upper limb belts.
• Belts of the lower extremities.

Scull

The skull consists of the bones of the facial and brain regions, which have an asymmetrical shape and are connected by sutures. Their main function is to protect the brain.

Brain section of the skull consists of eight bones.

Skull bones:

• 1 frontal bone forms the forehead and has two cavities, one above each eye.
• The 2 parietal bones form the crown of the skull.
• 1 occipital bone forms the base of the skull, it contains the opening for the spinal cord, through which the brain is connected to the rest of the body.
• The 2 temporal bones form the temples on the sides of the skull.
• 1 ethmoid bone forms part of the nasal cavity and has many small cavities on either side of the eyes.
• 1 sphenoid bone forms the eye sockets and has 2 cavities on either side of the nose.

Facial part of the skull consists of 14 bones.

Facial bones:

• The 2 zygomatic bones form the cheeks.
• The 2 bones of the upper jaw join to form the upper jaw, which contains openings for the upper teeth and the two largest cavities.
• 1 lower jaw has holes for the lower teeth. It is attached by synovial ellipsoidal joints, which provide jaw movement during speech and food consumption.
• The 2 nasal bones form the bridge of the nose.
• The 2 palatine bones form the floor and walls of the nose and the palate.
• The 2 turbinates form the sides of the nose.
• 1 coulter forms top part nose
• 2 lacrimal bones form 2 eye sockets, which have openings for the lacrimal ducts.

Spine

The spine consists of individual bones - vertebrae - which are asymmetrical and connected by cartilaginous joints, except for the first two vertebrae, which have synovial junction. The spine provides protection to the spinal cord and can be divided into five sections:

• Cervical (cervical) - includes seven bones of the neck and upper back. The first bone, the atlas, supports the skull and connects to occipital bone ellipsoidal joint. The second vertebra, epistropheus (axial), provides rotational movements of the head thanks to a cylindrical joint between it and the first cervical vertebra.
• Thoracic - consists of 12 bones of the upper and middle part of the spine, to which 12 pairs of ribs are attached.
• Lumbar - 5 bones of the lower back.
• The sacrum is the five fused bones that form the base of the back.
• The coccyx is a tail of four fused bones.

Rib cage

The rib cage consists of flat bones. It forms a protected cavity for the heart and lungs.

The bones and synovial joints that make up the chest include:

• 12 thoracic vertebrae of the spinal column.
• 12 pairs of ribs forming a cage at the front of the body.
• The ribs are connected to the vertebrae by flat joints that allow slow sliding movements of the chest during breathing.
• Each rib connects to a vertebra in the back.
• 7 pairs of ribs in front are attached to the sternum and are called the ribs themselves.
• The next three pairs of ribs are attached to the upper bones and are called false ribs.
• At the bottom there are 2 pairs of ribs that are not attached to anything and are called oscillating.

Shoulder girdle and arms

The shoulder girdle and arms consist of the following bones and synovial joints:

• The shoulder blades are flat bones.
• The collarbones are long bones.
• The joint between these bones is flat and allows a small amplitude of sliding movement.
• The shoulder contains the long humerus.
• The shoulder blades are connected to the humerus by ball-and-socket joints that allow a full range of movement.
• The forearm consists of the long ulna and radius bones.

The synovial elbow joint, connecting the three bones of the arm, is trochlear and allows flexion and straightening. The joint between the humerus and radius is cylindrical and also provides rotational movements. These rotational movements provide supination - rotation, in which the hand is turned palm up, and pronation - inward movement until the hand is palm down.

• Each wrist consists of 8 short bones.

At the wrist, the radius bone is connected to the carpal bones by an ellipsoidal joint, which allows flexion and extension, inward and outward movement.

• The 5 metacarpal bones form the palm and are miniature LONG bones.
• Each finger, except the 2 thumbs, consists of 3 phalanges - miniature long bones.
• The thumbs have 2 phalanges. There are 14 phalanges on each hand.

Lower limbs and legs

The lower extremity girdle and legs include the following bones and synovial joints:

• The sacrum and coccyx, located in the center of the pelvis, form the base of the spine.
• The pelvic bones form the prominent lateral surfaces of the pelvis, connected to the sacrum and coccyx by fibrous joints.
• Each pelvic bone consists of 3 fused flat bones:

1. Ilium in the groin area.
2. Pubic bone.
3. Ischium of the thigh.

• The long femur bones are located in the hips.
• The hip joints are ball-and-socket and allow unrestricted movement.
• The long tibia and fibula form the lower leg.

Lower limb belt

• The patella is formed by sesamoid bones.
• Seven short tarsal bones form the ankle.

The tibia, fibula, and tarsal bones are connected at the ankle by an ellipsoidal joint that allows the foot to flex, extend, and rotate inward and outward.

These four types of movement are called:

1. Flexion is the upward movement of the foot.
2. Plantar flexion - straightening the foot down.
3. Eversion - turning the foot outward.
4. Inversion - turning the foot inward.

• 5 miniature long metatarsal bones form the foot.
• Each finger, except the thumbs, has three miniature long bones - phalanges.
• The thumbs have two phalanges.

There are 14 phalanges on each foot, just like on the hands.

The tarsal bones are connected to each other and to the metatarsal bones by flat joints that allow only minor sliding movements. The metatarsal bones are connected to the phalanges by condyloid joints, and the phalanges are connected to each other by trochlear joints.

Arches of the feet

The foot has three arches, which distribute the body's weight between the ball of the foot and the ball of the foot when we stand or walk.

• Internal longitudinal arch - runs along the inside of the foot.
• External longitudinal - goes outside the foot.
• Transverse arch - runs across the foot.

The bones of the leg, the tendons that attach the muscles of the foot to them, determine the shape of these arches.

Functions of the skeletal system

Now that you are familiar with the structure of your skeleton, it will be useful to know exactly what functions the skeletal system performs.

The skeletal system has 5 main functions: protection, support and shape of the body, movement, storage and production of blood cells.

Protection

Bones protect internal organs:

• The skull is the brain.
• Spine - spinal cord.
• The chest is the heart and lungs.
• The lower extremity girdle is the reproductive organs.

Support and shaping

It is the bones that give the body its unique shape and also support its weight.

• Bones support the weight of the entire body: skin, muscles, internal organs and excess fat tissue.
• The shape of body parts such as the ears and nose is determined by cartilage, and it also supports bones where they connect to form joints.
• Ligaments provide additional support to the bones at joints.

Movement

The skeleton serves as a framework for the muscles:

• Tendons attach muscles to bones.
• Muscle contraction moves bones; the range of their movements is limited by the type of joint: maximum possibilities with a ball-and-socket joint, as in the synovial hip joint.

Storage

Minerals and blood fats are stored in bone cavities:

• Calcium and phosphorus, if they are in excess in the body, are deposited in the bones, helping to strengthen them. If the content of these substances in the blood decreases, it is replenished with them from the bones.
• Fats are also stored in the bones in the form of yellow bone marrow and, if necessary, are released from there into the blood.

Blood cell production

Red bone marrow, located in the spongy substance, produces new blood cells.

By studying the skeletal system, we can see how all parts of the body work as a whole. Always remember that each system works together with others, they cannot function separately!

Possible violations

Possible disorders of the skeletal system from A to Z:

• ANKYLOSING SPONDYLITIS is a joint disease that usually affects the spine and causes back pain and stiffness.
• ARTHRITIS - inflammation of the joints. It can be acute or chronic.
• PAGET'S DISEASE - thickening of the bone, painful.
• PAIN IN THE COCCYX usually occurs as a result of injury.
• BURSITIS is an inflammation of the synovial bursa that impedes joint movement. Bursitis of the knee is called prepatellar bursitis.
• BURSITIS OF THE BIG TOE - inflammation of the joint of the big toe, which increases with pressure.
• GANGLION - A harmless tumor of the ligaments near a joint. Usually occurs on the hands and feet.
• A HERNIATED DISC is a swelling of one of the fibrocartilaginous discs separating the vertebrae, which causes pain and muscle weakness.
• KYPHOSIS - curved curvature thoracic spine - hump.
• DUPUYTREN'S CONTRACTURE - limited flexion of the finger as a result of shortening and thickening of the fibrous tissue of the palm.
• LORDOSIS is a concave curvature of the lumbar spine.
• METATARSALGIA is pain in the arch of the foot, usually occurring in middle-aged, overweight people.
• HAMMER FINGER - a condition where, due to damage to the tendons, the finger does not straighten.
• OSTEOARTHRITIS is a disease in which joints are destroyed. The cartilage in the joint wears down, causing pain. In some cases, it is necessary to replace a joint, such as a knee or hip.
• OSTEOGENESIS is a defect in bone cells that causes brittle bones.
• OSTEOMALACIA, or rickets, is a softening of the bones as a result of a lack of vitamin D.
• OSTEOMYELITIS is an inflammation of the bones caused by a bacterial infection, often following local trauma.
• OSTEOPOROSIS is a weakening of bones that can be caused by changes in the levels of hormones estrogen and progesterone.
• OSTEOSARCOMA is a fast-growing malignant bone tumor.
• OSTEOCHONDRITIS - softening of the bone and, as a result, deformation. Occurs in children. FRACTURE - A bone that is broken or cracked as a result of trauma, extreme pressure on the bone, or because the bone is brittle, such as after an illness.
• HUMOMOUS PERIARTHRITIS - sharp pain in the shoulders. They occur in middle-aged and elderly people and make movement difficult. FLAT FOOT - insufficient arching of the foot, causing pain and tension. GOUT is a disorder of chemical processes, the symptoms of which are pain in the joints, most often the thumbs. Knees, ankles, wrists and elbows are also susceptible to the disease.
• A CARTILAGE TEAR is a knee injury caused by a forceful twist that damages the cartilage between the joints. STRAIN - A sprain or tear of a ligament that causes pain and inflammation. RHEUMATIC ARTHRITIS is a tumor that destroys joints. It first affects the fingers and toes, then spreads to the wrists, knees, shoulders, ankles and elbows.
• SYNOVITIS - post-traumatic inflammation of the joint.
• SCOLIOSIS - lateral curvature of the spine (relative to the midline of the back). CERVICAL VERTEBRATE DISPLACEMENT is the result of a sharp jerk of the neck back, damaging spine.
• STRESS - joint stiffness and constant overexertion are symptoms of excessive stress on the skeletal system.
• CHONDROSARCOMA is a slow-growing tumor, usually benign, which turns malignant. Harmony

Harmony

The skeletal system is a complex chain of organs on which the health of the entire organism depends. The skeleton, together with muscles and skin, determines appearance our body is a framework that is similar in all people and at the same time makes each person unique. For the skeletal system to function effectively: movement, protection, storage and reproduction, it must interact with the rest of the body's systems. It's very easy to take all this for granted; awareness of how the body should and should not work often places additional responsibility on us for our own body. There are many ways to ease and prolong the functioning of the skeletal system, the main one of which is maintaining a balance between internal and external care.

Liquid

Water makes up about 25% of bone; The synovial fluid that lubricates joints also consists of water. Most of this water comes from drinking and eating (from fruits and vegetables). Water from the digestive system enters the blood and then into the bones. It is important to maintain the level of water in the body by consuming the optimal amount of fluid. You need to understand the fundamental difference between healthy and harmful drinks. Plain water belongs to the first, do not underestimate it. The liquid is not useful and even harmful when it contains foreign additives, especially caffeine. Caffeine is found in coffee, tea, cola and acts as a diuretic, i.e. increases urine production and reduces the efficiency of fluid intake. With a lack of water in the body, bones become dry and brittle, and joints become stiff and more easily damaged.

Nutrition

Bones are constantly renewed: old cells are destroyed by osteoclasts, and new ones are formed by osteoblasts, which is why bones are very dependent on nutrition.

So, to maintain health, the skeletal system needs a nutritious diet:

• Calcium is found in Swiss cheeses and cheddar; it strengthens bones.
• Almonds and cashews are rich in magnesium; it also strengthens bones.
• Phosphorus is found in many foods and is essential for bone growth and development.
• Vitamin D is found in fish such as herring, mackerel and salmon; it promotes the absorption of calcium by bones.
• Vitamin C, found in peppers, watercress and cabbage, is needed for the production of collagen, which keeps bones and joints strong.
• Zinc, found in pecans, Brazil nuts and peanuts, promotes bone cell turnover.

Studies have shown that a diet oversaturated with proteins can cause calcium deficiency, since proteins are oxidizing agents, and calcium is a neutralizer. The higher the protein intake, the higher the need for calcium, which is removed from the bones, which ultimately leads to their weakening. This is the most common cause of osteoporosis.

The fight against free radicals continues in the skeletal system; antioxidants - vitamins A, C and E - increase its activity and prevent damage to bone tissue.

Rest

To maintain a healthy skeletal system, it is important to find the right proportion between rest and activity.

An imbalance can lead to:

• Stiff joints and resulting limited movement.
• Thin and weakened bones and associated weakness.

Activity

The skeletal system naturally develops more strength in bones that bear weight, while losing it in bones that are not used.

• Athletes can develop the bones they want by maintaining high content minerals.
• In people who are bedridden, bones become weak and thin as a result of loss of minerals. The same thing happens when plaster is applied to the bone. In this case, you will need to perform exercises to restore the bones.

The body independently determines its needs and responds to them by retaining or releasing calcium. And yet there is a limit to this process: too much stress can lead to damage to bones and joints if they are disproportionate to rest, just as insufficient activity leads to a lack of mobility!

Air

Individual sensitivity can affect the skeletal system. For example, many people have increased sensitivity to all kinds of vapors and exhaust gases. Once in the body, these substances reduce the efficiency of the skeletal system, resulting in an increased risk of diseases such as rheumatic and osteoarthritis, and people who already suffer from these diseases experience an exacerbation. Contact with exhaust gases should be avoided whenever possible. tobacco smoke and so on. Breathing in clean, Fresh air, we receive enough oxygen to nourish the skeletal system and activate the energy necessary for chemical reactions during its life.

Age

As we age, life processes in the body slow down, cells break down and eventually die. We cannot live forever, and our body is not able to always remain young due to many processes that we cannot control. During the aging process, the skeletal system gradually decreases its activity, bones weaken, and joints lose mobility. So we have a limited time when we can make full use of our body, which becomes more if we take proper care of our health. Now, with so many new opportunities, people's life expectancy has increased.

Color

The axial skeleton is the area where the seven main chakras are located. The word chakra is of Indian origin; in Sanskrit it begins with 1 “wheel”. Chakras are considered wheels of light that attract energy. We are talking about internal and external sources of energy that can influence human life processes. Each chakra is associated with a specific part of the body and has its own color. The anatomical location of the chakra indicates its connection with a particular organ, and the colors follow the sequence of the colors of the rainbow:

• The first chakra is located in the coccyx area; its color is red.
• The second chakra is located in the sacrum and is associated with the color orange.
• The third chakra is located between the lumbar and thoracic spine; its color is yellow.
• The fourth chakra is located at the top of the thoracic spine; its color is green.
• The fifth chakra is located in the cervical spine; its color is blue.
• The sixth chakra, blue, is located in the center of the forehead.
• The seventh chakra is located at the center of the crown and is associated with the color purple.

When a person is healthy and happy, these wheels spin freely, and their energy maintains beauty and harmony. Stress and illness are believed to block energy in the chakras; Blocks can be counteracted using appropriate colors. For example, public speaking is a very exciting process associated with the throat area; The color of this area is blue, so a blue scarf can activate the energy, which will make the task easier. To ignorant people, this may seem like eccentricity, and yet this method of stress relief is actually sometimes safer and more effective than more traditional ones.

Knowledge

Research has shown that our moral state greatly affects our physical state, i.e. “happiness leads to health.”

To be happy, a person needs to be accepted, and not so much by others, but by himself! How many times do we tell ourselves: “I don’t like my weight, my figure, my height?” All this is determined by the skeletal system, and we can develop very negative attitude to her if we hate our appearance. We cannot radically change our skeleton, so we need to learn to accept ourselves as we are. After all, it gives us so much movement and protection!

Negative thoughts lead to negative feelings, which in turn lead to illness and disorder. Anger, fear and hatred can have physical manifestations, having a negative impact on the health of the body. Don't forget that thanks to the skeletal system you can turn the pages of this book, sit on a chair, and work. Isn't this amazing?

Special care

The skeletal system's response to overload can lead to serious consequences for health, so it is very important to find harmony between internal and external factors to maintain its optimal condition.

External stress:

• Excessive stress resulting in stress and damage.
• Excessive repetitive movements leading to injury.

Internal stress refers to hormonal imbalance:

• Childhood is the time of most active bone development, which is regulated by hormones.
• Adolescence is a time of great change when, under the influence of hormones, the skeletal system takes on adult forms.
• During pregnancy, hormones regulate the development of the child and the health of the mother.
• During menopause, hormone levels change dramatically, which leads to a weakening of the skeletal system.
• When under emotional stress, hormones aimed at combating stress can have long-term harmful effects on the skeletal system. So, with a lack of bone nutrition, the digestive system will also suffer, and this in turn will complicate the renewal of bone tissue.

The needs of the skeletal system must be taken into account if we are to maintain normal work body, and fighting stress is a good start!

The structure of the human skeleton and bones, as well as their purpose, is studied by the science of osteology. Knowledge of the basic concepts of this science is a mandatory requirement for a personal trainer, not to mention the fact that this knowledge must be systematically deepened in the process of work. In this article we will consider the structure and functions of the human skeleton, that is, we will touch on the basic theoretical minimum that literally every personal trainer must master.

And according to the old tradition, as always, we’ll start with a short excursion about what role the skeleton plays in the human body. Structure human body, which we talked about in the corresponding article, forms, among other things, the musculoskeletal system. This is a functional set of skeletal bones, their joints and muscles, which through nervous regulation moving in space, maintaining postures, facial expressions and other motor activity.

Now that we know that the human musculoskeletal system forms the skeleton, muscles and nervous system, we can proceed directly to studying the topic indicated in the title of the article. Since the human skeleton is a kind of supporting structure for attaching various tissues, organs and muscles, this topic can rightfully be considered the foundation in the study of the entire human body.

Structure of the human skeleton

Human skeleton- a functionally structured set of bones in the human body, which is part of its musculoskeletal system. This is a kind of frame on which tissues, muscles are attached, and in which internal organs are located, for which it also acts as protection. The skeleton consists of 206 bones, most of which are combined into joints and ligaments.

Human skeleton, front view: 1 - lower jaw; 2 - upper jaw; 3 - zygomatic bone; 4 - ethmoid bone; 5 - sphenoid bone; c - temporal bone; 7- lacrimal bone; 8 - parietal bone; 9 - frontal bone; 10 - eye socket; 11 - nasal bone; 12 - pear-shaped hole; 13 - anterior longitudinal ligament; 14 - interclavicular ligament; 15 - anterior sternoclavicular ligament; 16 - coracoclavicular ligament; 17 - acromioclavicular ligament; 18 - coracoacromial ligament; 19 - coracohumeral ligament; 20 - costoclavicular ligament; 21 - radiate sternocostal ligaments; 22 - external intercostal membrane; 23 - costoxiphoid ligament; 24 - ulnar collateral ligament; 25 - radial roundabout (lateral) ligament; 26 - annular ligament of the radius; 27 - iliopsoas ligament; 28 - ventral (abdominal) sacroiliac ligaments; 29 - inguinal ligament; 30 - sacrospinous ligament; 31 - interosseous membrane of the forearm; 32 - dorsal intercarpal ligaments; 33 - dorsal metacarpal ligaments; 34 - roundabout (lateral) ligaments; 35 - radial roundabout (lateral) ligament of the wrist; 36 - pubofemoral ligament; 37 - iliofemoral ligament; 38 - obturator membrane; 39 - superior pubic ligament; 40 - arcuate ligament of the pubis; 41 - fibular roundabout (lateral) ligament; 42 - patellar ligament; 43 - tibial roundabout (lateral) ligament; 44 - interosseous membrane of the leg; 45 - anterior tibiofibular ligament; 46 - bifurcated ligament; 47 - deep transverse metatarsal ligament; 48 - roundabout (lateral) ligaments; 49 - dorsal metatarsal ligaments; 50 - dorsal metatarsal ligaments; 51 - medial (deltoid) ligament; 52 - scaphoid bone; 53 - calcaneus; 54 - toe bones; 55 - metatarsal bones; 56 - sphenoid bones; 57 - cuboid bone; 58 - talus; 59 - tibia; 60 - fibula; 61 - patella; 62 - femur; 63 - ischium; 64 - pubic bone; 65 - sacrum; 66 - ilium; 67 - lumbar vertebrae; 68 - pisiform bone; 69 - triangular bone; 70 - capitate bone; 71 - hamate bone; 72 - metacarpal bones; 7 3-bones of the fingers; 74 - trapezoid bone; 75 - trapezium bone; 76 - scaphoid bone; 77 - lunate bone; 78 - ulna; 79 - radius; 80 - ribs; 81 - thoracic vertebrae; 82 - sternum; 83 - shoulder blade; 84 - humerus; 85 - collarbone; 86 - cervical vertebrae.

Human skeleton, rear view: 1 - lower jaw; 2 -upper jaw; 3 - lateral ligament; 4 - zygomatic bone; 5 - temporal bone; 6 - sphenoid bone; 7 - frontal bone; 8 - parietal bone; 9- occipital bone; 10 - awl-mandibular ligament; 11-nuchal ligament; 12 - cervical vertebrae; 13 - collarbone; 14 - supraspinous ligament; 15 - blade; 16 - humerus; 17 - ribs; 18 - lumbar vertebrae; 19 - sacrum; 20 - ilium; 21 - pubic bone; 22- coccyx; 23 - ischium; 24 - ulna; 25 - radius; 26 - lunate bone; 27 - scaphoid bone; 28 - trapezium bone; 29 - trapezoid bone; 30 - metacarpal bones; 31 - bones of the fingers; 32 - capitate bone; 33 - hamate bone; 34 - triangular bone; 35 - pisiform bone; 36 - femur; 37 - patella; 38 - fibula; 39 - tibia; 40 - talus; 41 - calcaneus; 42 - scaphoid bone; 43 - sphenoid bones; 44 - metatarsal bones; 45 - toe bones; 46 - posterior tibiofibular ligament; 47 - medial deltoid ligament; 48 - posterior talofibular ligament; 49 - calcaneofibular ligament; 50 - dorsal tarsal ligaments; 51 - interosseous membrane of the leg; 52 - posterior ligament of the head of the fibula; 53 - fibular roundabout (lateral) ligament; 54 - tibial roundabout (lateral) ligament; 55 - oblique popliteal ligament; 56 - sacrotuberous ligament; 57 - flexor retinaculum; 58 - roundabout (lateral) ligaments; 59 - deep transverse metacarpal ligament; 60 - pea-hooked ligament; 61 - radiate ligament of the wrist; 62-ulnar roundabout (lateral) ligament of the wrist; 63 - ischiofemoral ligament; 64 - superficial dorsal sacrococcygeal ligament; 65 - dorsal sacroiliac ligaments; 66 - ulnar roundabout (lateral) ligament; 67-radial roundabout (lateral) ligament; 68 - iliopsoas ligament; 69 - costotransverse ligaments; 70 - intertransverse ligaments; 71 - coracohumeral ligament; 72 - acromioclavicular ligament; 73 - coracoclavicular ligament.

As mentioned above, the human skeleton consists of about 206 bones, of which 34 are unpaired, the rest are paired. 23 bones make up the skull, 26 - the spinal column, 25 - the ribs and sternum, 64 - the skeleton of the upper limbs, 62 - the skeleton of the lower limbs. Skeletal bones are formed from bone and cartilage tissue, which belong to connective tissues. Bones, in turn, consist of cells and intercellular substance.

The human skeleton is designed in such a way that its bones are usually divided into two groups: the axial skeleton and the accessory skeleton. The first includes bones located in the center and forming the basis of the body, these are the bones of the head, neck, spine, ribs and sternum. The second includes the collarbones, shoulder blades, bones of the upper, lower extremities and pelvis.

Central skeleton (axial):

• The skull is the basis of the human head. It houses the brain, organs of vision, hearing and smell. The skull has two sections: the brain and the facial.
• The rib cage is the bony base of the chest and the location for the internal organs. Consists of 12 thoracic vertebrae, 12 pairs of ribs and sternum.
• The spinal column (spine) is the main axis of the body and the support of the entire skeleton. The spinal cord runs inside the spinal canal. The spine has the following sections: cervical, thoracic, lumbar, sacral and coccygeal.

Secondary skeleton (accessory):

• Belt of the upper limbs - due to it, the upper limbs are attached to the skeleton. Consists of paired shoulder blades and clavicles. Upper limbs adapted to perform labor activity. The limb (arm) consists of three sections: the shoulder, forearm and hand.
• Lower limb girdle – provides attachment of the lower limbs to the axial skeleton. It houses the organs of the digestive, urinary and reproductive systems. The limb (leg) also consists of three sections: thigh, lower leg and foot. They are adapted to support and move the body in space.

Functions of the human skeleton

The functions of the human skeleton are usually divided into mechanical and biological.

Mechanical functions include:

• Support – the formation of a rigid osteochondral frame of the body to which muscles and internal organs are attached.
• Movement - the presence of movable joints between the bones allows the body to move with the help of muscles.
• Protection of internal organs - the chest, skull, spinal column and more, serve as protection for the organs located in them.
• Shock-absorbing – the arch of the foot, as well as the cartilage layers at the joints of the bones, help reduce vibrations and shocks when moving.

TO biological functions relate:

• Hematopoietic – the formation of new blood cells occurs in the bone marrow.
• Metabolic - bones are the storage site for a significant portion of the body's calcium and phosphorus.

Sexual features of the skeleton structure

The skeletons of both sexes are mostly similar and do not have radical differences. These differences include only minor changes in the shape or size of specific bones. Most obvious features The structures of the human skeleton look like this. In men, the bones of the limbs tend to be longer and thicker, and the muscle attachment points tend to be more lumpy. Women have more wide pelvis, including a narrower chest.

Types of bone tissue

Bone- active living tissue consisting of compact and spongy substance. The first looks like dense bone tissue, which is characterized by the arrangement of mineral components and cells in the form of a Haversian system (the structural unit of bone). It includes bone cells, nerves, blood and lymph vessels. More than 80% of bone tissue has the form of the Haversian system. The compact substance is located in the outer layer of the bone.

Bone structure: 1- bone head; 2- pineal gland; 3- spongy substance; 4- central bone marrow cavity; 5- blood vessels; 6- bone marrow; 7- spongy substance; 8- compact substance; 9- diaphysis; 10- osteon

Spongy substance does not have a Haversian system and makes up 20% of the bone mass of the skeleton. The spongy substance is very porous, with branched septa that form a lattice structure. This spongy structure of bone tissue allows for the storage of bone marrow and fat storage and at the same time ensures sufficient bone strength. The relative content of dense and spongy matter varies in different bones.

Bone development

Bone growth is an increase in bone size due to an increase in bone cells. The bone can increase in thickness or grow in the longitudinal direction, which directly affects the human skeleton as a whole. Longitudinal growth occurs in the area of ​​the epiphyseal plate (the cartilaginous area at the end of a long bone) initially as a process of replacing cartilage tissue with bone tissue. Although bone tissue is one of the most durable tissues in our body, it is important to recognize that bone growth is a very dynamic and metabolically active tissue process that occurs throughout a person's life. Distinctive feature bone tissue is its high content of minerals, primarily calcium and phosphates (which give bones strength), as well as organic components (which provide bones with elasticity). Bone tissue has unique opportunities for growth and self-healing. The structural features of the skeleton also mean that, through a process called bone remodeling, the bone can adapt to the mechanical loads to which it is subjected.

Bone growth: 1- cartilage; 2- formation of bone tissue in the diaphysis; 3- growth plate; 4- formation of bone tissue in the epiphysis; 5- blood vessels and nerves

I- fruit;II- newborn;III- child;IV- young man

Restructuring of bone tissue– the ability to modify bone shape, size and structure in response to external influences. This physiological process, including resorption (resorption) of bone tissue and its formation. Resorption is the absorption of tissue, in this case bone. Restructuring is a continuous process of destruction, replacement, maintenance and restoration of bone tissue. It is a balanced process of bone resorption and formation.

Bone tissue is formed by three types of bone cells: osteoclasts, osteoblasts and osteocytes. Osteoclasts are large cells that destroy bone and carry out the process of resorption. Osteoblasts are cells that form bone and new bone tissue. Osteocytes are mature osteoblasts that help regulate the process of bone tissue remodeling.

FACT. Bone density is largely dependent on regular physical activity over a long period of time, and exercise physical exercise, in turn, help prevent bone fractures by increasing their strength.

Conclusion

This amount of information, of course, is not an absolute maximum, but rather a necessary minimum of knowledge required by a personal trainer in his professional activities. As I have said in articles about being a personal trainer, the foundation of professional development is continuous learning and improvement. Today we have laid the foundation in such a complex and voluminous topic as the structure of the human skeleton, and this article will be only the first in a thematic series. In the future, we will consider a lot more interesting and useful information regarding the structural components of the human body frame. In the meantime, you can confidently say that the structure of the human skeleton is no longer “terra incognita” for you.