The following parts are distinguished in the skeleton: the skeleton of the trunk (vertebrae, ribs, sternum), the skeleton of the head (bones of the skull and face), the bones of the girdles of the limbs - upper (scapula, clavicle) and lower (pelvic) and bones of free limbs - upper (shoulder, bones forearm and hand) and lower (thigh, bones of the lower leg and foot).
By their external form, bones are distinguished tubular, spongy, flat and mixed.
I. Tubular bones... They are part of the skeleton of the limbs and are divided into long tubular bones(shoulder and bones of the forearm, thigh and lower leg bones) with endochondral foci of ossification in both epiphyses (biepiphyseal bones) and short tubular bones(clavicle, bones of the metacarpus, metatarsus and phalanges of the fingers), in which the endochondral focus of ossification is present only in one (true) epiphysis (monoepiphyseal bones).
II. Spongy bones... Among them there are long spongy bones(ribs and sternum) and short(vertebrae, wrist bones, tarsus). Spongy bones include sesamoid bones, i.e. sesame plants similar to sesam seeds (patella, pisiform bone, sesamoid bones of fingers and toes); their function is auxiliary devices for the work of muscles; development - endochondral in the thickness of the tendons.
III. Flat bones: a) flat skull bones(frontal and parietal) perform predominantly a protective function. These bones develop on the basis of connective tissue (integumentary bones); b) flat bones belts(scapula, pelvic bones) perform the functions of support and protection, develop on the basis of cartilage tissue.
IV. Mixed bones(bones of the base of the skull). These include bones that come together from several parts that have different functions, structure and development. The clavicle, which develops partly endesmally, partly endochondrically, can also be attributed to mixed bones.
BONE STRUCTURE IN X-RAY
IMAGE
X-ray examination of the skeleton reveals both the external and internal structure of the bone directly on a living object. On radiographs, a compact substance is clearly distinguishable, giving an intense contrasting shadow, and a spongy substance, the shadow of which has a reticular character.
Compact substance the epiphyses of tubular bones and the compact substance of the spongy bones looks like a thin layer bordering the spongy substance.
In the diaphysis of tubular bones, the compact substance is different in thickness: in the middle part it is thicker, towards the ends it narrows. At the same time, between the two shadows of the compact layer, the bone marrow cavity is noticeable in the form of some enlightenment against the background of the general shadow of the bone.
Spongy substance on the roentgenogram, it looks like a looped network, consisting of bone crossbeams with enlightenments between them. The nature of this network depends on the location of the bone plates in this area.
X-ray examination of the skeletal system becomes possible from the 2nd month of uterine life, when ossification points. Knowledge of the location of ossification points, the timing and order of their appearance in practical terms is extremely important. Non-confusion of additional points of ossification with the main part of the bone can be the reason for diagnostic errors.
All major points of ossification appear in the bones of the skeleton before puberty, called puberty. With its onset, the fusion of the epiphyses with the metaphyses begins. This is radiographically expressed in the gradual disappearance of enlightenment at the site of the metaepiphyseal zone corresponding to the epiphyseal cartilage that separates the pineal gland from the metaphysis.
Aging bones... In old age, the skeletal system undergoes the following changes, which should not be interpreted as symptoms of pathology.
I. Changes caused by atrophy of the bone substance: 1) a decrease in the number of bone plates and bone loss (osteoporosis), while on the roentgenogram the bone becomes more transparent; 2) deformation of the articular heads (the disappearance of their rounded shape, "grinding" of the edges, the appearance of "corners").
II. Changes caused by excessive deposition of lime in the connective tissue and cartilage formations adjacent to the bone: 1) narrowing of the articular X-ray gap due to calcification of the articular cartilage; 2) bone growths - osteophytes, formed as a result of calcification of ligaments and tendons at the site of their attachment to the bone.
The described changes are normal manifestations of age-related variability of the skeletal system.
BODY SKELETON
The elements of the trunk skeleton develop from the primary segments (somites) of the dorsal mesoderm (sclerotome), lying on the sides of the chorda dorsalis and neural tube. The vertebral column is composed of a longitudinal row of segments - vertebrae, which arise from the nearest halves of two adjacent sclerotomes. At the beginning of the development of the human embryo, the spine consists of cartilaginous formations - the body and the neural arch, which lie metamerically on the dorsal and ventral sides of the notochord. Subsequently, the individual elements of the vertebrae grow, which leads to two results: firstly, to the fusion of all parts of the vertebra and, secondly, to the displacement of the notochord and its replacement by the vertebral bodies. The chord disappears, remaining between the vertebrae in the form of a nucleus pulposus in the center of the intervertebral discs. The superior (neural) arches cover the spinal cord and merge, forming unpaired spinous and paired articular and transverse processes. The lower (ventral) arches give ribs that lie between the muscle segments, covering the general body cavity. The spine, having passed the cartilaginous stage, becomes bony, with the exception of the spaces between the vertebral bodies, where the intervertebral cartilage that connects them remains.
The number of vertebrae in a row of mammals fluctuates dramatically. While there are 7 cervical vertebrae, in the thoracic region the number of vertebrae fluctuates according to the number of remaining ribs. A person has 12 thoracic vertebrae, but there may be 11-13. The number of lumbar vertebrae also varies, a person has 4-6, more often 5, depending on the degree of fusion with the sacrum.
In the presence of the XIII rib, the first lumbar vertebra becomes, as it were, the XIII thoracic vertebra, and only four lumbar vertebrae remain. If the XII thoracic vertebra does not have a rib, then it is likened to the lumbar ( lumbarization); in this case, there will be only eleven thoracic vertebrae, and six lumbar vertebrae. The same lumbarization can occur with the I sacral vertebra if it does not fuse with the sacrum. If the V lumbar vertebra grows together with the I sacral vertebra and becomes similar to it ( sacralization), then the sacral vertebrae will be 6. The number of coccygeal vertebrae is 4, but ranges from 5 to 1. As a result, the total number of human vertebrae is 30-35, most often 33. Human ribs develop in the thoracic region, in the rest of the ribs remain in a rudimentary form, merging with the vertebrae.
The skeleton of the human body has the following characteristic features due to the vertical position and development of the upper limb as an organ of labor:
1) vertically located spinal column with bends;
2) a gradual increase in the vertebral bodies from top to bottom, where in the area of connection with the lower limb through the belt of the lower limb, they merge into a single bone - the sacrum;
3) a wide and flat chest with a predominant transverse dimension and the smallest anteroposterior.
Vertebral column
Vertebral column, columna vertebralis, has a metameric structure and consists of separate bone segments - vertebrae, vertebrae, superimposed sequentially one on top of the other and related to short cancellous bones.
The vertebral column plays the role of an axial skeleton, which is the support of the body, the protection of the spinal cord located in its canal and is involved in the movements of the trunk and skull.
General properties of the vertebrae... According to the three functions of the spinal column, each vertebra, vertebra (Greek spondylos), has:
1) the supporting part, located in front and thickened in the form of a short column, - body, corpus vertebrae;
2) arc, arcus vertebrae, which attaches to the body behind two legs, pedunculi arcus vertebrae, and closes vertebral foramen, foramen vertebrale; from the totality of the vertebral holes in the spinal column is formed spinal canal, canalis vertebralis, which protects the spinal cord from external damage. Consequently, the arch of the vertebra performs mainly the function of protection;
3) on the arc there are devices for the movement of the vertebrae - processes. On the middle line from the arc moves back spinous process, processus spinosus; on the sides on each side - on transverse, processus transversus; up and down - paired articular processes, processus articulares superiores et inferiores. The latter restrict from behind clippings, incisurae vertebrales superiores et inferiores, from which, when one vertebra is superimposed on another, intervertebral foramen, foramina intervertebralia, for the nerves and vessels of the spinal cord. The articular processes serve to form the intervertebral joints, in which the movements of the vertebrae occur, and the transverse and spinous processes serve to attach the ligaments and muscles that set the vertebrae in motion.
In different parts of the vertebral column, individual parts of the vertebrae have different sizes and shapes, as a result of which the vertebrae are distinguished: cervical (7), thoracic (12), lumbar (5), sacral (5) and coccygeal (1-5).
The supporting part of the vertebra (body) in the cervical vertebrae is relatively little expressed (in the 1st cervical vertebra, the body is even absent), and downward, the vertebral bodies gradually increase, reaching the largest size in the lumbar vertebrae; the sacral vertebrae, carrying the entire weight of the head, trunk and upper limbs and connecting the skeleton of these parts of the body with the bones of the girdle of the lower limbs, and through them with the lower limbs, grow together into a single sacrum ("strength in unity"). On the contrary, the coccygeal vertebrae, which is the remainder of the tail that disappeared in humans, look like small bony formations, in which the body is barely expressed and there is no arc.
The arch of the vertebra as a protective part in the places of thickening of the spinal cord (from the lower cervical to the upper lumbar vertebrae) forms a wider vertebral foramen. In connection with the end of the spinal cord at level II of the lumbar vertebra, the lower lumbar and sacral vertebrae have a gradually narrowing vertebral foramen, which completely disappears in the coccyx.
The transverse and spinous processes, to which muscles and ligaments are attached, are more pronounced where more powerful muscles are attached (lumbar and thoracic regions), and on the sacrum, due to the disappearance of the tail muscles, these processes decrease and, merging, form small ridges on the sacrum. Due to the fusion of the sacral vertebrae in the sacrum, the articular processes disappear, which are well developed in the mobile parts of the spinal column, especially in the lumbar.
Thus, in order to understand the structure of the spinal column, it must be borne in mind that the vertebrae and their individual parts are more developed in those departments that experience the greatest functional load. On the contrary, where the functional requirements decrease, there is also a reduction in the corresponding parts of the spinal column, for example, in the coccyx, which in humans has become a rudimentary formation.
Bone classification
There are various classifications that cover all types of bones of the human skeleton, depending on their location, structure and function.
1. By location : cranial bones; trunk bones; limb bones.
2. By development distinguish the following types of bones : primary (emerging from connective tissue); secondary (formed from cartilage); mixed.
3. There are the following types of human bones in structure: tubular; spongy; flat; mixed.
Tubular bones
Tubular long bones are composed of both dense and spongy substance. They can be divided into several parts. The middle of the bone is formed by a compact substance and has an elongated tubular shape. This area is called the diaphysis. Its cavities first contain red bone marrow, which is gradually replaced by yellow, containing fat cells. At the ends of the tubular bone is the epiphysis - this is the area formed by the cancellous substance. Red bone marrow is placed inside it. The area between the diaphysis and the pineal gland is called the metaphysis. During the period of active growth of children and adolescents, it contains cartilage, due to which the bone grows. Over time, the anatomy of the bone changes, the metaphysis completely turns into bone tissue. Long tubular bones include the thigh, shoulder, and forearm bones. Tubular small bones have a slightly different structure. They have only one true pineal gland and, accordingly, one metaphysis. These bones include the phalanges of the fingers, the bones of the metatarsus. They function as short levers of movement.
Spongy bones
The name of the bones often indicates their structure. For example, cancellous bones are formed from a cancellous substance covered with a thin layer of compact. They do not have developed cavities, so the red bone marrow is placed in small cells. The cancellous bones are also long and short. The former include, for example, the sternum and ribs. Short spongy bones are involved in the work of muscles and are a kind of auxiliary mechanism. These include the bones of the wrist, vertebrae.
Flat bones
These types of human bones, depending on their location, have a different structure and perform certain functions. The bones of the skull are primarily a defense for the brain. They are formed by two thin plates of dense substance, between which is spongy. It contains holes for veins. The flat bones of the skull develop from connective tissue. The scapula and pelvic bones are also flat bones. They are formed almost entirely from a spongy substance that develops from cartilage tissue. These types of bones perform the function of not only protection, but also support.
Mixed bones
Mixed bones are a combination of flat and short cancellous or tubular bones. They develop in various ways and perform the functions that are necessary in one or another part of the human skeleton. Such types of bones, as mixed, are found in the body of the temporal bone, vertebrae. These include, for example, the collarbone.
Cartilage tissue
Cartilage tissue has an elastic structure. It forms the auricles, nose, and some parts of the ribs. Cartilage tissue is also located between the vertebrae, as it perfectly resists the deforming force of loads. It has high strength, excellent abrasion and crush resistance.
Morphology, physiology and pathophysiology of the musculoskeletal system.
Movement plays a huge role in living nature and is one of the main adaptive reactions to the environment and a necessary factor in human development. The movement of a person in space is carried out thanks to the musculoskeletal system.
The musculoskeletal system is formed by bones, their joints and striated muscles.
Bones and their joints are the passive part of the musculoskeletal system, and muscles are active.
General anatomy of the skeleton. The human skeleton (skeletos) consists of more than 200 bones, 85 of them are paired, interconnected with the help of connective tissue having a different structure.
Skeleton functions .
The skeleton performs mechanical and biological functions.
To mechanical functions skeleton include:
Protection,
· traffic.
The bones of the skeleton form cavities (spinal canal, skull, chest, abdominal, pelvis) that protect the internal organs located in them from external influences.
Support is carried out by attaching muscles and ligaments to various parts of the skeleton, as well as by supporting the internal organs.
Movement is possible in the places of movable joints of the bones - in the joints. They are set in motion by muscles, under the control of the nervous system.
To biological functions skeleton include:
Participation of bones in metabolism, especially in mineral - is a depot of mineral salts (phosphorus, calcium, iron, etc.)
· Participation of bones in hematopoiesis. The function of hematopoiesis is performed by the red bone marrow contained in the cancellous bones.
Mechanical and biological functions have a mutual influence on each other.
Each bone occupies a certain position in the human body, has its own anatomical structure and performs its functions.
Bone consists of several types of tissues, the main place of which is occupied by the hard connective tissue - bone.
Outside the bone is covered periosteum except for articular surfaces covered with articular cartilage.
Bone contains red bone marrow, adipose tissue, blood vessels, lymph vessels and nerves.
The chemical composition of the bone. Bone consists of 1/3 organic (ossein, etc.) and 2/3 inorganic (calcium salts, especially phosphates) substances. Under the action of acids (hydrochloric, nitric, etc.), calcium salts dissolve, and the bone with the remaining organic matter will retain its shape, but become soft and elastic. If the bone is burned, the organic matter will burn, and the inorganic will remain. The bone will also retain its shape, but it will become very fragile. It follows that the elasticity of the bone depends on the ossein, and the mineral salts give it hardness.
In childhood, bones contain more organic matter, so bones in children are more flexible and rarely break. In older people, inorganic substances predominate in the chemical composition of the bones, the bones become less elastic and more fragile, therefore they break more often.
Bone classification. According to the classification of M.G., Bone gains are: tubular, spongy, flat and mixed.
Tubular bones they are long and short and perform the functions of support, protection and movement. Tubular bones have a body, a diaphysis, in the form of a bone tube, the cavity of which is filled in adults with yellow bone marrow. The ends of the tubular bones are called epiphyses. The cells of the spongy tissue contain red bone marrow. Between the diaphysis and the epiphyses, the metaphyses are located, which are zones of bone growth in length.
Spongy bones distinguish between long (ribs and sternum) and short (vertebrae, wrist bones, tarsus).
They are constructed of a spongy substance covered with a thin layer of compact. Spongy bones include sesamoid bones (patella, pisiform bone, sesamoid bones of the fingers and toes). They develop in the tendons of muscles and are auxiliary devices for their work.
Flat bones, forming the roof of the skull, built of two thin plates of compact substance, between which there is a spongy substance, diploe, containing cavities for veins; the flat bones of the girdles are built of spongy substance (scapula, pelvic bones). Flat bones serve as support and protection,
Mixed bones merge from several parts that have different functions, structure and development (bones of the base of the skull, collarbone).
Question 2. Types of bone joints.
All bone joints can be divided into 2 groups:
1) continuous connections - synarthrosis (motionless or inactive);
2) discontinuous connections - diarthrosis or joints (movable in function).
The transitional form of bone joints from continuous to discontinuous is characterized by the presence of a small gap, but the absence of an articular capsule, as a result of which this form is called a semi-joint or symphysis.
Continuous connections are synarthrosis.
There are 3 types of synarthrosis:
1) Syndesmosis - the connection of bones using ligaments (ligaments, membranes, sutures). Example: the bones of the skull.
2) Synchondrosis is the connection of bones with the help of cartilaginous tissue (temporary and permanent). The cartilage tissue located between the bones acts as a buffer to soften shocks and concussions. Example: vertebrae, first rib and vertebra.
3) Synostosis - the connection of bones through bone tissue. Example: pelvic bones.
Discontinuous joints, joints - diarthrosis. At least two are involved in the formation of joints articular surfaces , between which is formed cavity , closed joint capsule . Articular cartilage covering the articular surfaces of the bones is smooth and elastic, which reduces friction and cushions shock. Articular surfaces match or not match. The articular surface of one bone is convex and is the articular head, and the surface of the other bone is respectively concave, forming an articular cavity.
The joint capsule attaches to the bones that make up the joint. Hermetically closes the articular cavity. It consists of two membranes: outer fibrous and inner synovial. The latter secretes a clear fluid into the joint cavity - synovia, which moisturizes and lubricates the articular surfaces, reducing friction between them. In some joints, the synovium forms protruding into the joint cavity and contains a significant amount of fat.
Sometimes protrusions or eversions of the synovium are formed - synovial bags lying near the joint, at the place where the tendons or muscles fit. The bursae contain synovial fluid and reduce the friction of the tendons and muscles during movement.
An articular cavity is a hermetically sealed slit-like space between the articular surfaces. The synovial fluid creates a pressure in the joint below atmospheric pressure, which prevents the separation of the articular surfaces. In addition, synovia is involved in fluid exchange and joint strengthening.
Question 3. The structure of the skeleton of the head, trunk and limbs.
The following parts are distinguished in the skeleton:
1. axial skeleton
Trunk skeleton (vertebrae, ribs, sternum)
· The skeleton of the head (bones of the skull and face) form;
2. additional skeleton
Limb girdle bones
Upper (scapula, collarbone)
Lower (pelvic bone)
Bones of free limbs
Upper (shoulder, forearm and hand bones)
Lower (thigh, lower leg and foot bones).
Vertebral column is part of the axial skeleton, performs supporting, protective and locomotor functions: ligaments and muscles are attached to it, protects the spinal cord located in its canal and participates in the movements of the trunk and skull. The vertebral column is S-shaped due to the person's upright posture.
The vertebral column has the following sections: cervical, consisting of 7, thoracic - from 12, lumbar - from 5, sacral - from 5 and coccygeal - from 1-5 vertebrae. The sizes of the vertebral bodies gradually increase from top to bottom, reaching the largest sizes at the lumbar vertebrae; the sacral vertebrae grow together into a single bone, due to the fact that they bear the weight of the head, trunk and upper limbs.
The coccygeal vertebrae are the remnants of the tail that disappeared in humans.
Where the spine experiences the greatest functional load, the vertebrae and their individual parts are well developed. The coccygeal spine does not carry any functional load and therefore is a rudimentary formation.
The vertebral column in the human skeleton is located vertically, but not straight, but forms bends in the sagittal plane. Bends in the cervical and lumbar regions are directed forward and are called lordosis , and in the thoracic and sacral - facing the bulge back - this is kyphosis ... Curvatures of the spine form after the birth of a child and become permanent by the age of 7-8.
With an increase in the load, the bends of the spinal column increase, with a decrease in the load, they become smaller.
Bends of the spinal column are shock absorbers during movement - they soften shocks along the spinal column, thus protecting the skull and the brain located in it from excessive shock.
If these bends of the spinal column in the sagittal plane are the norm, then the appearance of bends in the frontal plane (more often in the cervical and thoracic regions) is considered a pathology and is called scoliosis ... The reasons for the formation of scoliosis can be different. For example, schoolchildren may develop a very pronounced lateral curvature of the spinal column - school scoliosis, as a result of improper landing or carrying a load (bag) in one hand. Scoliosis can develop not only in schoolchildren, but also in adults of certain professions associated with torso curvature during work. For the prevention of scoliosis, special gymnastics is required.
In old age, the spinal column becomes shorter due to a decrease in the thickness of the intervertebral discs, the vertebrae themselves and the loss of elasticity. The vertebral column bends anteriorly to form one large thoracic bend (senile hump).
The vertebral column is a fairly mobile formation. Thanks to the intervertebral discs and ligaments, it is flexible and elastic. The cartilage pushes the vertebrae apart, and the ligaments connect them together.
Chest form 12 thoracic vertebrae, 12 pairs of ribs and sternum.
Sternum consists of three parts: the handle, the body and the xiphoid process. The jugular notch is located on the upper edge of the handle.
There are 12 pairs of ribs in the human skeleton. With their posterior ends, they connect to the bodies of the thoracic vertebrae. The 7 upper pairs of ribs with their front ends connect directly to the sternum and are called true ribs ... The next three pairs (VIII, IX and X) are joined by their cartilaginous ends to the cartilage of the previous rib and are called false edges ... XI and XII pairs of ribs are located freely in the muscles of the abdomen - this is oscillating ribs .
Rib cage has the shape of a truncated cone, the upper end of which is narrow, and the lower end is wider. Due to upright posture, the chest is somewhat compressed from front to back.
The lower ribs form the right and left costal arches. Under the xiphoid process of the sternum, the right and left costal arches converge, limiting the sub-sternal angle, the size of which depends on the shape of the chest.
Shape and size chest depends on: age, sex, physique, degree of development of muscles and lungs, lifestyle and profession of a given person. Vital organs are located in the chest - the heart, lungs, etc.
Distinguish 3 chest shape : flat, cylindrical and conical.
In people with well-developed muscles and lungs, brachymorphic body type, the chest becomes wide, but short and acquires conical shape... She is all the time in a state of inhalation. The sub-sternal angle of such a chest will be obtuse.
In people of a dolichomorphic body type, with poorly developed muscles and lungs, the chest becomes narrow and long. This shape of the chest is called flat. Its anterior wall is almost vertical, the ribs are strongly inclined. The chest is, as it were, in a state of exhalation.
Do people have brachymorphic ?? (meso) body type the chest has cylindrical shape, occupying an intermediate position between the two previous ones. In women, the rib cage is shorter and narrower in the lower part than in men, and more rounded. In the process of growth and development, social factors influence the shape of the chest.
Poor living conditions and inadequate nutrition in children can significantly affect the shape of the chest. Children growing up with a lack of nutrition and solar radiation develop rickets ("English disease"), in which the chest takes the shape of a "chicken breast". It is dominated by the anteroposterior dimension, and the sternum protrudes forward. In children, with an incorrect sitting posture, the chest is long and flat. The musculature is poorly developed. The chest is, as it were, in a collapsed state, which negatively affects the activity of the heart and lungs. For the correct development of the chest and the prevention of diseases in children, physical education, massage, proper nutrition, adequate lighting and other conditions are needed.
Scull (cranium) is a receptacle for the brain and the senses associated with the latter; in addition, it surrounds the initial sections of the digestive and respiratory tracts. In this regard, the skull is divided into 2 parts: cerebral and facial. The cranial skull has a vault and a base.
Cerebral section of the skull in humans they form: unpaired - occipital, sphenoid, frontal and ethmoid bones and paired - temporal and parietal bones.
Facial section of the skull form paired - upper jaw, lower nasal concha, palatine, zygomatic, nasal, lacrimal and unpaired - opener, lower jaw and sublingual.
The bones of the skull are connected to each other, mainly by sutures.
In the skull of a newborn, the cerebral section of the skull is relatively larger than the facial one. As a result, the facial skull protrudes little forward in comparison with the brain and makes up only an eighth of the latter, while in an adult this ratio is 1: 4. The fontanelles are located between the bones that form the cranial vault. The fontanelles are the remnants of the membranous skull, they are located at the intersection of the sutures. The fontanelles are of great functional importance. The bones of the cranial vault can overlap each other during childbirth, adapting to the shape and size of the birth canal.
The wedge-shaped and mastoid fontanelles are overgrown either at the time of birth or immediately after birth. Newborns have no sutures. The bones have smooth surfaces. There is cartilaginous tissue between the separate parts of the bones of the base of the skull that have not yet fused. The sinuses in the bones of the skull are absent. The upper and lower jaws are poorly developed: the alveolar processes are almost absent, the lower jaw ?? the jaw consists of two non-fused halves. In adulthood, ossification of the seams of the skull is observed.
Skeleton of the upper and lower limbs has a general plan of the structure and consists of two sections: belts and free upper and lower limbs. Through the belts, the free limbs are attached to the body.
Upper limb belt form two paired bones: the clavicle and the scapula.
Skeleton of the free upper limb consists of three sections: proximal - the humerus; middle - two bones of the forearm - ulna and radius; and distal - the bones of the hand.
The hand has three sections: the wrist, the metacarpus and the phalanges of the fingers.
Wrist form eight short spongy bones arranged in 2 rows. Each row has four bones.
Pastern (metacarpus) is formed by five short tubular metacarpal bones
The bones of the fingers of the hand are the phalanges. Each finger has three phalanges located one behind the other. The exception is the thumb, which has only two phalanges.
Tubular bones they are long and short and perform the functions of support, protection and movement. Tubular bones have a body, a diaphysis, in the form of a bone tube, the cavity of which is filled in adults with yellow bone marrow. The ends of the tubular bones are called epiphyses. The cells of the spongy tissue contain red bone marrow. Between the diaphysis and the epiphyses, the metaphyses are located, which are zones of bone growth in length.
Spongy bones distinguish between long (ribs and sternum) and short (vertebrae, wrist bones, tarsus).
They are constructed of a spongy substance covered with a thin layer of compact. Spongy bones include sesamoid bones (patella, pisiform bone, sesamoid bones of the fingers and toes). They develop in the tendons of muscles and are auxiliary devices for their work.
Flat bones , forming the roof of the skull, built of two thin plates of compact substance, between which there is a spongy substance, diploe, containing cavities for veins; the flat bones of the girdles are built of spongy substance (scapula, pelvic bones). Flat bones serve as support and protection,
Mixed bones merge from several parts that have different functions, structure and development (bones of the base of the skull, collarbone).
Question 2: Types of bone joints.
All bone joints can be divided into 2 groups:
continuous connections - synarthrosis (motionless or inactive);
discontinuous connections - diarthrosis or joints (movable in function).
The transitional form of bone joints from continuous to discontinuous is characterized by the presence of a small gap, but the absence of an articular capsule, as a result of which this form is called a semi-joint or symphysis.
Continuous connections are synarthrosis.
There are 3 types of synarthrosis:
Syndesmosis is the connection of bones using ligaments (ligaments, membranes, sutures). Example: the bones of the skull.
Synchondrosis is the connection of bones with the help of cartilage tissue (temporary and permanent). The cartilage tissue located between the bones acts as a buffer that softens shocks and concussions. Example: vertebrae, first rib and vertebra.
Synostosis is the connection of bones through bone tissue. Example: pelvic bones.
Discontinuous joints, joints - diarthrosis . At least two are involved in the formation of joints articular surfaces , between which is formed cavity , closed joint capsule . Articular cartilage covering the articular surfaces of the bones are smooth and elastic, which reduces friction and softens shocks. Articular surfaces match or not match. The articular surface of one bone is convex and is the articular head, and the surface of the other bone is respectively concave, forming an articular cavity.
The joint capsule attaches to the bones that make up the joint. Hermetically closes the articular cavity. It consists of two membranes: outer fibrous and inner synovial. The latter secretes a clear fluid into the joint cavity - synovia, which moisturizes and lubricates the articular surfaces, reducing friction between them. In some joints, the synovium forms protruding into the joint cavity and contains a significant amount of fat.
Sometimes protrusions or eversions of the synovium are formed - synovial bags lying near the joint, at the place where the tendons or muscles fit. The bursae contain synovial fluid and reduce the friction of the tendons and muscles during movement.
An articular cavity is a hermetically sealed slit-like space between the articular surfaces. The synovial fluid creates a pressure in the joint below atmospheric pressure, which prevents the separation of the articular surfaces. In addition, synovia is involved in fluid exchange and joint strengthening.
Loading ...