The upper limb is an organ of labor. This leaves a significant imprint on its structure. Like the skeleton of the torso and head, the skeleton of the upper limb consists of bones and their joints (Figure 29).
Rice. 29. Skeleton of the upper limb
The skeleton of the upper limb consists of upper limb girdle and free upper limb (Figure 30). The upper limb girdle (shoulder girdle) consists of shoulder blades and clavicle... Thanks to the shoulder girdle, the free upper limb hangs down behind the line of gravity of the body, helping to maintain its vertical position. In humans, the shoulder girdle is not closed, which facilitates movement of the upper limb and protects the chest from concussions and jolts.
Rice. 30. Bones of the upper limb. Front view:
1 - clavicle, 2 - sternal end, 3 - scapula, 4 - coracoid process of the scapula, 5 - glenoid cavity of the scapula, 6 - humerus, 7 - coronary fossa of the humerus, 8 - medial epicondyle of the humerus, 9 - humerus block, 10 - coronoid process, 11 - tuberosity of the ulna, 12 - ulna, 13 - head of the ulna, 14 - wrist bones, 15-1-5th metacarpal bones, 16 - phalanges of the fingers, 17 - styloid process of the radius, 18 - radius, 19 - head of the radius, 20 - crest of the greater tubercle, 21 - intertubular groove, 22 - greater tubercle, 23 - lesser tubercle, 24 - head of the humerus, 25 - acromion
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Collarbone- steam room, S- a figuratively curved bone, in which the body and 2 ends are distinguished: the sternum and acromial (Fig. 31 b). There are articular surfaces at both ends for articulation with the corresponding bones. In some people, the clavicle is thin and almost straight, in others it is strongly curved. It depends on the development and activity of the muscles that attach to it. The acromial end of the clavicle is flattened and convex towards the front. The upper surface of the clavicle is smooth, the lower surface is rough, showing traces of attachment of muscles and ligaments. The clavicle is the only bone that connects the upper limb to the bones of the trunk. Rice. 31. Bones of the shoulder girdle:
a - the right scapula behind; b
- bottom right clavicle:
1 - upper, 2 - lower and 3 - lateral angles; 4 - medial, 5 - lateral and - 6 upper edge; 7 - awn; 8 - supraspinatus pit, 9 infraspinatus pit; 10 - acromion; 11 - clipping; 12 - coracoid process; 13 - neck; 14 - subarticular tuberosity; 15 - sternal and 16 - acromial ends of the clavicle
Scapula- flat bone, triangular in shape (Fig. 31 a). It has 3 edges: superior, medial and lateral; 3 angles: superior, lateral and inferior. The scapula is located on the chest at the back, adjacent to the ribs along the length of 2 to 7 ribs. The costal and dorsal surfaces are distinguished in it. Costal - slightly concave, forms a subscapular fossa, where the muscle of the same name originates. Dorsal - divided by a high ridge (awn) into the supraspinatus and infraspinatus fossa, in which the muscles of the same name are located. Laterally, the spine of the scapula continues into the acromion (process), which has an articular surface for articulation with the clavicle. The upper edge of the scapula passes into the coracoid process, at the base of which there is a deep notch of the scapula. The lateral angle ends with a thickening with a deepened glenoid cavity for the head of the humerus, which is separated from the bone by a slightly pronounced neck of the scapula. The scapula serves as a support for the upper limb, connecting in the lateral angle with the humerus. The scapula has no connections with the skeleton of the body; it is, as it were, inserted between the clavicle and the free part of the upper limb.
The skeleton of the free upper limb consists of 3 parts: proximal - humeral bone; medium - bones forearms- radial and ulnar; distal skeleton - bones brushes: bones of the wrist, metacarpals and phalanges of the fingers (see Fig. 30). Most of the bones of the upper limb are tubular bones, therefore, for each bone it is necessary to determine the body (diaphysis) and 2 ends (pineal glands) - proximal and distal. Only after that, proceed to the study of the basic anatomical formations on them. In addition, it is necessary to determine the correct position of the bone on the skeleton and be able to find it on your own limb.
Shoulder the bone has a cylindrical body, which in the distal direction takes the form of a trihedral prism (Fig. 32). The proximal epiphysis is thickened and forms a spherical head, articulating with the glenoid cavity of the scapula. A narrow anatomical neck separates the head from the body. Under the anatomical neck there are 2 tubercles: large (lateral) and small (medial), to which muscles are attached. From each tubercle, ridges go down, between which there is an intertubercular groove for the tendon of the biceps muscle. Below the tubercles is the surgical neck, so named because in this area the bone most often breaks during trauma. On the upper - lateral surface of the body, there is a deltoid tuberosity - the place of attachment of the tendon of the muscle of the same name. The distal epiphysis of the bone is thickened and widened and ends with a condyle for articulation with the bones of the forearm in the elbow joint. There are 2 articular surfaces on the condyle: laterally the head for articulation with the radius, medially located a block for articulation with the ulna. In front of the head of the condyle is the radial fossa, above the block - the coronary one, where the coronal process of the ulna enters when flexing in the elbow joint. Behind the block of the humerus is the large fossa of the olecranon of the ulna. The bony septum between the olecranon fossa and the coronary fossa is thin and sometimes has a hole.
Rice. 30. Humerus
a - front view: 1 - anatomical neck; 2 - the head of the humerus; 3 - crest of a small tubercle; 4 - surgical neck; 5 - feeding hole; 6 - medial edge; 7 - front surface; 8 - coronary fossa; 9 - medial epicondyle; 10 - block of the humerus; 11 - the head of the condyle; 12 - lateral epicondyle; 13 - radial fossa; 14 - lateral surface; 15 - lateral edge; 16 - deltoid tuberosity; 17 - crest of a large tubercle; 18 - inter-tuberous groove; 19 - small tubercle; 20 - large tubercle;
b rear view: 1 - head; 2 - anatomical neck; 3 - large tubercle; 4 - surgical neck; 5 - feeding hole; 6 - back surface; 7 - ulnar fossa; 8 - lateral epicondyle; 9 - block of the humerus; 10 - radial nerve groove; 11 medial epicondyle.
From the medial and lateral sides of the epicondyle of the humerus, elevations are visible - epicondyles: medial and lateral. Muscles and ligaments are attached to them. The medial epicondyle is larger than the lateral one. The humerus is oriented so that the head on the proximal epiphysis and the medial great epicondyle are facing medially (towards the midline of the body); the coronal smaller fossa is forward, and the ulnar deeper one is backward.
Forearm bones include ulnar and beam bones (fig. 33 a and b). In the anatomical position of the hand (the hand is lowered down, palm forward), the ulna is located medially (continuation of the 5th finger), the radial bone is located laterally (continuation of the thumb of the hand).
Ulnar the bone has a body resembling a triangular prism, and 2 pineal glands. On the more massive proximal epiphysis there are 2 processes - the ulnar (behind) and the coronary (in front), separated by a block-like notch articulating with the humerus block. On the lateral surface of the coronoid process there is a radial notch for the circumference of the radial head. The lower (distal) rounded epiphysis of the ulna forms a head, on the lateral surface of which there is an articular surface for articulation with the radius. The styloid process extends downward from the medial edge of the head. The position of the ulna is determined as follows: it is placed on the forearm with a thickened end to the elbow joint, while the larger process (ulna) should be oriented backward, and the coronary one - forward. The interosseous ridge should be directed towards the radius.
Rice. 33. Radius and ulna of the forearm (right).
a - front view: 1 - olecranon; 2 - tuberosity of the ulna; 3 - the front edge of the ulna; 4 - the inner edge of the ulna; 5 - subulate process of the ulna; 6 - articular circumference of the head of the ulna; 7 - subulate process of the radius; 8 - lateral surface of the radius; 9 - the anterior surface of the radius; 10 - radial tuberosity; 11 - neck of the radius; 12 - articular circumference of the radial head; 13 - the head of the radius; 14 - glenoid fossa of the radial head; 15 - coronal process of the ulna; 16 - elbow notch;
b - rear view: 1 - glenoid fossa of the radial head; 2 - the head of the radius; 3 - articular circumference of the radial head; 4 - the neck of the radius; 5 - posterior edge of the radius; 6 - the posterior surface of the radius; 7 - subulate process of the radius; 8 - ulnar notch of the radius; 9 - subulate process of the ulna; 10 - the inner edge of the ulna; 11 - posterior edge of the ulna; 12 - the ulna of the ulna.
Beam the bone on the forearm is positioned so that its head is on the proximal pineal gland (closer to the elbow joint), and the thickened end is distal (closer to the hand). The anterior surface of the distal radial epiphysis is flattened. In this area, the radial artery is pressed while counting the pulse. On the head there is a glenoid fossa for articulation with the head of the condyle of the humerus and an articular circle for articulation with the radial notch of the ulna. Below the head is a narrow neck, under which is the tuberosity of the radius (the place of attachment of the tendon of the biceps brachii muscle). On the distal epiphysis of the radius there is a carpal articular surface for articulation with the proximal row of the wrist bones, which laterally passes into the styloid process. On the medial edge of the distal pineal gland is the ulnar notch, which is involved in the formation of the joint with the ulna.
Rice. 34. Bones of the hand, right, palmar surface
1 - scaphoid, 2 - lunate, 3 - triangular, 4 - pisiform, 5 - trapezoid bone, 6 - trapezoidal, 7 - capitate, 8 - hook-shaped, 9 - IV metacarpal bones, 10 - proximal phalanges, 11 - middle II phalanges, 12 - distal (nail) phalanges, 13 - sesamoid bones
Brush has a skeleton, subdivided into the bones of the wrist, the metacarpal bones and the bones of the fingers of the hand - the phalanges of the fingers (Fig. 34). The bones of the wrist are arranged in 2 rows. In the proximal row lie (starting from the radial edge or from the first toe) scaphoid, lunate, trihedral and pisiform (sesamoid bone); in the distal: the bone is a trapezoid (large polygonal), trapezoidal, capitate and hook-shaped. The bones of the wrist form a bony arch, convex towards the rear, and concavity towards the palm. This forms a groove in the wrist, in which the flexor tendons of the fingers pass. Three bones of the proximal row (with the exception of the pisiform) form, as it were, a single elliptical articular surface for articulation with the bones of the forearm.
Metacarpals bones - 5 short tubular bones, each of which is distinguished: base - thickened end facing the wrist, body and head (rounded distal end of the bone). On the base and the head there are articular surfaces for articulation with the bones of the wrist and phalanges of the fingers. The first metacarpal bone is shorter and wider than the rest; it articulates with the large polygonal bone by a biaxial saddle joint, which causes greater mobility of 1 toe.
In the hand, the shortest and thickest of the fingers are distinguished - the thumb, followed by the index, middle (longest), ring and little fingers. Each toe has 3 phalanges: proximal, middle, and distal. The exception is the thumb, which does not have a middle phalanx. In each phalanx, a base directed to the metacarpus, body and head are distinguished. Articular surfaces for articulation with adjacent bones are located at the base and head of the phalanx. The distal phalanges on the head have no articular surface.
The structural features of the human hand, indicating the adaptability of the human hand to labor activity, are: a relatively small hand length, amounting to 10-11% of the body length (in great apes, this figure is 16-21%); relatively wide wrist; the thumb is highly developed in length and power (in monkeys it is shorter, it may be absent with the intensive growth of 2-5 fingers), capable of opposing the rest of the fingers due to the saddle carpometacarpal joint of this finger, which makes it possible to grasp objects (monkeys perform only grasping movements ); the scaphoid bone and the trapezium bone are displaced in the wrist, which entailed a deepening of the wrist sulcus; the phalanges of the 2nd and 5th fingers are shorter and straightened, which allows for more subtle movements.
After examining the bones of the upper limb, it is necessary to complete the following task: assemble the skeleton of the upper limb from individual bones (front view). Then proceed to consider the joints of the girdle of the upper limb and the free upper limb according to the scheme proposed earlier, paying special attention to the articular surfaces of the bones, the shape of which determines the nature and range of movements in the joints. For students of the Institute of Physical Education, consider the location of the ligaments and understand which movements they direct and which ones inhibit. This is necessary to know in order to prevent injuries during physical education and sports.
Complete tasks in the application: 8, 9, 10, 11.
Control questions
1. Departments of the skeleton of the upper limb. Which bones belong to each of the departments?
2. What is the structure of the scapula and clavicle?
3.How to distinguish the left shoulder blade and the left clavicle from the right?
4. Name the joints of the upper limb girdle. What type of joints are they?
5. What formations are there on the humerus? What are the characteristics of the right or left humerus?
6.What arm movements are possible in the shoulder joint?
7. What is the structure of the ulna and radius? What are the characteristics of the right or left of each of them?
8. How do the forearm bones connect?
9. What movements of the forearm are possible in the elbow joint?
10. What type of joints does the elbow joint belong to?
11. What departments are distinguished in the hand? List the bones of each section.
12. What is the structure of the wrist joint?
13. What are the characteristics of the hand joints?
14. Characteristic features of the structure of the human hand.
The upper limbs of a person allow you to make various movements that are necessary to perform the most simple or complex actions.
To understand the diseases of the bones of this section, it is important to know the structure of the skeleton of the upper extremities.
The upper limb is the most mobile, therefore its role in the human body is significant.
The main function of the upper limbs is the ability to make extensive hand movements, which is necessary when performing various types of work activities.
The skeleton of the arms allows a person to perform flexion and extension, adduction and abduction, circular movements and rotation of the upper limbs.
There are also biological functions of the skeleton, which consist in the participation of bones in metabolic processes, as well as in hematopoiesis.
Upper limbs: skeletal structure
In the skeleton of the limbs, a free part and a belt are distinguished.
The shoulder blade and belong to the belt of the upper extremities. The scapula is the bone adjacent to the sternum, located at the level of the second to seventh ribs. This bone is similar to a triangle and therefore an upper, lateral and lower angle are distinguished in it. The clavicle consists of a rounded body and an acromial and sternal end.
The free part consists of the following departments:
- Distal part
- Average
- Proximal
The distal part is the carpal bones. Allocate carpal, metacarpal and digital bones in this section of the skeleton. The wrist bones are composed of eight spongy but short bones that are arranged in two rows. The metatarsus are also short, tubular. They distinguish between two sections - the body and the head.
The number of finger bones is five. The thickest and shortest bone is at the first (thumb) toe. From him the count is kept: second (index), third (middle), fourth (unnamed) and fifth (little finger).
The main function of the skeleton of the upper limbs is to provide a variety of hand movements
The middle part of the skeleton consists of two types of bones: the radius and ulna. They are the bones of the forearm. The ulna begins with the fifth toe, its upper end is thickened, has two branches - the coronary, which is located in front and the ulna, which is behind.
The radius is located on the side of the first finger (thumb).
Bone belongs to the proximal part of the skeleton. The shoulder joint is formed by the cavity of the scapula and the head of the humerus.
The humerus is tubular. In it, the body is distinguished, as well as the lower and upper end, which is separated from the body, the so-called anatomical neck. Below there are small elevations - a small and large tubercle, which are separated by an intertubercular groove.
Pathologies in the structure of the skeleton
Diseases of the parts of the skeleton of the upper extremities can be congenital or acquired.
Clubhand is a congenital pathology. It is caused by shortened tendons, ligaments or muscles of the palmar-radial region, as well as an abnormal phenomenon such as the absence of the ulna or radius. This is extremely rare, most often these bones are underdeveloped.
Amelia or phocomelia is a pathology in which a limb is completely or partially absent.
Syndactyly, ectrodactyly and polydactyly are also considered congenital defects. With syndactyly, the shape of the fingers is disturbed, or the fusion of the digital bones is impossible. Ectrodactyly is characterized by the absence of bone in one or more fingers. With polydactyly, there is an increase in the number of fingers on the hand.
There are the following pathologies in the structure of the skeleton:
- Among diseases of the upper extremities, osteochondropathy should be distinguished. This disease is a necrotic aseptic process that occurs in the spongy bones, which has a chronic form and leads to microfractures.
- Dislocations are also considered the most common pathologies of the bones of the upper extremities. They can be either congenital or acquired. A fracture of the first type occurs during difficult childbirth. Also, during labor, there may be a fracture of the shoulder. Acquired fractures are distinguished between open and closed.
- Diseases of the shoulder joint include periarthrosis of the shoulder scapula. This disease often leads to a complication - calcification.
Neoplasms - chondroma, osteoidosteoma, chondroblastoma - are benign, sarcoma - malignant, which affect the bones of the upper extremities.
Among the diseases of the elbow joint, bursitis is often diagnosed, which is usually provoked by prolonged injuries during sports, as well as injuries to the shoulder area at work.
Experts say that common diseases of the skeleton of the upper extremities are arthrosis, the cause of which is most often the inflammatory processes inside the joints. Arthritis, which affects the area of the wrist joint, is also particularly common.
- a disease of the hand, characterized by an inflammatory process, which proceeds in an acute form.
Phlegmon of the hand is considered a dangerous pathology of the hand. The disease is usually a complication of tendon panaritium. Phlegmon between the fingers quickly spreads into the deep tissue of the palm. If the tendon sheath is affected, pus can enter the wrist and forearm.
Pathologies in the structure of the skeleton of the upper extremities are characterized by a mass of unpleasant symptoms that significantly reduce the quality of human life. If the patient notes the presence of signs of pathology of the upper extremities, then he should contact a specialist who will establish the correct diagnosis, which will prevent complications.
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The upper limb is connected to the body by the bones of the shoulder girdle (scapula and collarbone), as well as by muscles that begin on the trunk and attach to these bones. The shoulder girdle, consisting mainly of two bones - the scapula and the clavicle, serves not only to support the upper limb, but with its movements in the acromioclavicular and sternoclavicular joints significantly increases its mobility due to the fact that when the arm is raised above the horizontal of movement occur in these joints.
The shoulder girdle is the muscles covering the bones of the shoulder girdle: deltoid, trapezoid, pectoralis major, etc., form the shoulder girdle, the shape of which is a characteristic bulge, and the normal position of the humerus head plays an important role in maintaining this shape.
The shoulder joint is formed by the head of the humerus and the glenoid cavity of the scapula. Being the most mobile joint, the shoulder joint is at the same time one of the most vulnerable. The movements in the shoulder joint are combined with the movements of the shoulder girdle.
Shoulder. When viewed from the front, the contoured biceps muscle of the shoulder is clearly visible, on both sides of which two grooves are clearly visible. The radial vein is directed along the outer groove from bottom to top, and the ulnar vein along the inner groove, which is accompanied by the internal cutaneous nerve. The anastomosis of the veins forms, as it were, the letter M, which, being translucent, is often clearly visible in the depths of the subcutaneous tissue of the cubital fossa of the forearm.
In the area of the inner groove of the shoulder, the brachial artery passes, which is accompanied by two veins and the median nerve. When the fingers are inserted into the internal groove, the pulsation of the brachial artery can be clearly felt.
On the back of the shoulder, the contour of the triceps muscle is highlighted. The humerus is palpable only in persons with poorly developed muscles. The head of the humerus is located only in the region of the axillary cavity, in the depth of which the neurovascular bundle passes, consisting of the axillary artery and vein and the trunks of the brachial plexus, which gives the upper limb its main branches: axillary nerve, ulnar, radial and median. In the region of the proximal end of the humerus under the deltoid muscle below the acromial process by 1 - 0.5 cm with a rotational movement of the shoulder, you can feel the large tubercle of the humerus head and inside it the groove corresponding to the intertubercular groove of the humerus, in which the tendon of the long head of the biceps muscle lies ... A small tubercle of the humerus is located medially of the groove. In the region of the distal end of the humerus, the lateral and medial epicondyle of the shoulder is felt behind, between which the olecranon protrudes posteriorly. The medial epicondyle of the shoulder has a groove in which the ulnar nerve passes. The groove, like the nerve, is easily felt behind the medial epicondyle.
The elbow joint is a complex joint formed by the epiphyses of three bones - the ulna, radius and humerus. Anatomically, it is a combination of three joints: brachioradial, brachioradial and radioulnar proximal, having a common capsule and an articular cavity. The most superficial are the areas of the articular capsule on both sides of the olecranon. In front and behind, the capsule of the elbow joint is closed by the tendons of the biceps and triceps muscles. In the area of the elbow bend, it is easy to feel from the front: the tendon of the biceps muscle, which passes into the tendon extension of the aponeurosis, rough projections on both sides of the lower end of the humerus, behind - the olecranon of the ulna - the place of attachment of the triceps muscle, the lateral and medial grooves of the olecranon and lateral process it is the head of the radius, which is best defined by pronation and supination of the forearm.
The forearm, consisting of the ulna and radius, connected by an interosseous ligament, is covered in the proximal region by muscles, in the distal - by their tendons. The bones of the forearm in their upper part are palpable from the sides, and in the lower half also from the back and palmar sides. The styloid processes of both bones protruding under the skin are also clearly felt.
The wrist joint, or wrist area, separates the forearm from the hand. The identification points of the wrist joint are the styloid processes. In the formation of this joint, the radial bone is involved from the side of the forearm, and from the side of the hand - the proximal row of the bones of the wrist, namely (counting from the thumb to the little finger) the scaphoid bone, lunate, triangular and pisiform.
The identification points of the wrist joint are the styloid processes. Of these, the styloid process of the ulna is clearly visible, and the radius is easily palpable.
The hand is divided into three parts: a) the wrist, consisting of 8 bones, arranged in two rows of 4 bones each. See above for the location of the bones in the proximal row. In the distal row, counting from the thumb to the little finger, there are: large polygonal bone, small polygonal, capitate, hooked; b) the metacarpus, consisting of 5 long metacarpal bones; c) fingers formed by phalanges, of which the 1st finger has two phalanges, the rest of the fingers have three phalanges. On the palmar side of the wrist, at the radial and ulnar ends of the bones of the forearm, two bony protrusions are well defined: at the radial end, this protrusion is formed by a scaphoid, and at the ulnar end, by a pea-shaped bone. Slightly below these protrusions, on the palm, there are two elevations formed by the muscles of the thumb and little finger. In the area of the elevation of the thumb, the palmar branch of the median nerve branches, and in the area of the elevation of the little finger, the palmar branch of the ulnar nerve. The heads of the metacarpal or metacarpal bones are palpable from the palmar, even better from the back of the hand. On the dorsum of the hand, the gaps between the metacarpal bones and then the heads of the main phalanges are also felt, which are clearly visible when the fingers are bent into a fist.
Circulation. The arterial supply comes from the subclavian artery system. Venous outflow occurs through the subclavian vein.
The lymphatic vessels on the upper extremities are located as follows: on the dorsum and palmar surfaces of the fingers, they pass transversely, reaching the lateral surfaces of the fingers, then rise to the palm, from the palm, the vessels pass to the forearm and shoulder, almost vertically upward, and flow into the truncus subclavius, having passed previously through groups of lymph nodes. In the same way, the lymphatic vessels of the upper limb divert lymph to the axillary, and from there to the supraclavicular and subclavian lymph nodes.
The innervation of the upper limb is carried out by the brachial plexus.
A.F. Verbov
"The structure of the upper limbs" and other articles from the section
Joints and ligaments are also distinguished as their constituent parts. The upper limbs consist of: the bones of the shoulder, forearm, hands (wrists, pasterns and phalanges of the fingers).
Characteristics of the humerus
This limb element is a long tubular bone. It includes the so-called body and 2 pineal glands: the upper proximal and lower distal. The upper section has a rounded shape, and the lower one is triangular. The shoulder joint is the junction of the upper epiphysis with the glenoid fossa of the scapula. All bones of the skeleton of the upper extremities consist of a body and pineal glands and are connected to each other.
The structure and function of the ulna
According to the anatomical structure, the ulna and radius are referred to as the forearm. The ulna consists of many long bones and two ends (proximal and distal pineal gland). The base of the bone is presented in the form of a trihedron; it has certain edges, which are named as follows: anterior (palmar), posterior (dorsal), interosseous (external). The leading edge of the bone is round. The rear one goes back a little. The interosseous edge has a pointed shape and faces the radius.
In contrast to the distal, the proximal pineal gland is more thickened. The blocky notch, which is located in it, is completely covered with articular cartilage. This is necessary so that the edges of the bone are not erased with constant movement of the upper limb. The ulnar notch is also located at the ends of the block-shaped notch. The anterior surface of the bone, located below the coronoid process, has a tuberous structure.
The upper and lower epiphyses of the radial and ulnar interacts with each other through the joints. Any connection of the bones of the upper limbs is a complex mechanism, especially in the elbow area. If an injury occurs and the bones are damaged or shattered, many actions and operations will be done by specialists before the elbow can work again.
The lateral side (outer surface) of this element of the upper limb includes a radial notch, a notch for the entry of the radial head. This cavity for the front of the bone and the bone itself form the proximal joint of the forearm.
Like the lateral side of the distal epiphysis, the posterior medial section has an styloid process, which is necessary for better ligament of the limb elements. We see that the ulna is very complex, which, together with the radius, forms the bones of the upper limb. Human anatomy - the structure of all organs and systems, including the bones and joints of his limbs - is generally not elementary.
Radial bone of the upper limb
The difference between the two components of the forearm is that the distal end of the radius is much thicker than the proximal end. This end forms a rounded head in which there is a pineal gland with a flat depression. Thanks to this, the correct connection of the bones occurs. This head is the surface of the joint. On the anterior side of the radius, there is a part that is responsible for the attachment of the biceps muscle of the shoulder joint. Structural elements of the wrist are connected to the radius through a massive distal pineal gland. The lower epiphyses of the radius and ulna, joining together, form the radioulnar joint.
Wrist characteristics
The bones of the upper limbs of a person consist of short elements arranged in 2 rows (proximal and distal), and have an unusual shape. At the wrist, it is presented in the form of a curved groove, the bulge of which faces the back of the hand.
In the proximal row, small bones are located, which were named according to their shape: lunate, scaphoid, triangular. In addition, there is still a pisiform bone, which adjoins the triangular element with the palmar surface. The distal row is formed by trapezoidal, capitate and hook-shaped bones. To perform their functions, all of the listed structural components are ordered so that they are not in the same plane. The carpal bones of the upper limbs of a person of the proximal row form an elliptical bulge. It connects to the distal epiphysis of the radial part of the upper limb. And in the distal row, the bones are articulated with the metacarpal.
Upper limb bones
The metacarpal phalanges of the fingers are formed by tubular bones (with one pineal gland), which have a body, base, and head. They are curved, with the convex side facing the back of the hand. The distal row of carpal bones is connected to their bases, and the heads are connected to the beginning of the phalanges. The heads adjoin the bases of the proximal phalanges, and their head articulates with the beginning of the distally located phalanges. Each toe has 3 phalanges: proximal, middle, and distal. However, they only have two.
Each phalanx, like all the other bones of the upper limbs, the anatomy of which is described above, also has a base, body and head. But their peculiarity lies in the fact that they are lined up one after another. Moreover, all three phalanges have only one true pineal gland. The proximal parts of the wrist have one fossa where they connect to the next bone. The middle and distal phalanges are slightly different from the proximal ones, as they have two fossae for the formation of a joint. These grooves are flat, separated by small combs. Each last phalanx in the toe is slightly narrowed from above, flattened and rough.
Bones of the free upper limb, their connection
All bones are interconnected by joints, this enables a person to move indefinitely. The connection of the bones of the upper limbs, clavicle and scapula is represented by the combination of two paired joints: the articulation of the sternal ends of the clavicle with the handle of the sternum and its acromial ends with the acromions of the scapula. The next ligament of the scapula is the upper transverse, has the form of a short thin bundle, thrown over the notch of the scapula. The opening for the advancement of nerves and blood vessels is formed by the transverse ligament with the notch and very often ossifies. In humans, the structure of the bones of the upper extremities is very diverse.
The acromioclavicular joint can move in any direction, but the frequency of movement is low. They are hindered by the coracoclavicular ligament. It is subdivided into quadrangular and triangular ligaments. The quadrangular is in the shape of a trapezoid, and the triangular is in the shape of a cone. Both ligaments are angled towards each other.
Description of the shoulder joint
The shoulder joint plays an important role in the movement of the upper limb bone. The shoulder joint is formed by the head of the humerus and the glenoid cavity of the scapula. This depression is oval in shape, occupies one quarter of the head area, and is slightly concave. The articular lip present in it increases the congruence of the connecting tissues covered with hyaline cartilage. The joint capsule has freedom of movement, therefore, when the bone is lowered, it can fold into folds. It is strengthened by muscles, ligaments located in the shoulder joint. The head of the shoulder is tightly fixed by muscles and ligaments in the glenoid cavity. There are no muscles in the antero-lower part of the shoulder joint. It is surrounded by mucous bags that interact with the articular cavity.
Blood flows to the shoulder joint through the anterior and posterior arteries located around the shoulder bone. This connection of bones is very mobile, it is characterized by the following actions: rotation, circular movements, extension, flexion, abduction, reduction. In humans, the bones of the upper and lower extremities are slightly different, but the joints are the same in structure.
Elbow Difficulty
The elbow joint is formed by the junction of the humerus, ulna, and radius. There are three small joints inside this large joint:
- brachio-ulnar;
- brachioradial;
- radioulnar.
Due to the presence of a joint capsule and a common cavity, they are combined into a complex joint covered with hyaline cartilage.
The brachio-ulnar and brachioradial joints, working together, cause flexion and extension, and the radial-ulnar joint participates in the movements of the forearm. The various movements are due to the presence of a large number of muscles. Such a complex mechanism cannot exist without support. And the joint has this support in the form of the ulnar and radial ligaments. They wrap around the head of the bone of the upper limb. Human anatomy is designed in such a way that through this, the joint is prevented from bending in the opposite direction.
How do the forearm bones connect?
The radius and ulna are located side by side, and their ends are connected at the joint. The epiphyses of these structures are connected by the distal and proximal joints. For the strength of the connection, there is a membrane between these bones, which is the beginning of the deep muscles of this part of the upper limbs. The upper joint (proximal) is an integral part of the elbow joint, while the lower one acts independently. The distal radioulnar joint is separated from the radiocarpal joint by a small articular disc. It has the shape of a triangle with concave plate surfaces.
The structure of the wrist joint
The bones of the wrist are connected to the radius using the articular disc and the surfaces of all participants in the connection. The proximal rows of the wrist bones are strongly interconnected, so the articular surface is one area from the side of the wrist. It is naturally smaller than the radius of the radius, so the triangle-shaped disc helps to connect two different-sized articular areas. In addition, it helps to separate the ulna from the joint, which is surrounded by ligaments on all sides.
Which joints are involved in connecting the bones of the hand and fingers?
The bones of the hand are connected to each other using three joints:
- Mid-carpal. It is located between the bones of the first and second row of the wrist. There are many ligaments on the two surfaces of the wrist (palmar and dorsum). This is due to the fact that the hands are actively functioning, they must perform small movements, bend, unbend. This strong ligamentous apparatus is called the ligamentous ligament of the wrist.
- Carpometacarpal. Four have one capsule and an articular plane. The joint of the thumb is separated from the rest.
The bones of the fingers are connected to each other using the metacarpophalangeal and interphalangeal joints. In addition to them, there are still a large number of strong ligaments on each finger, which allows a person to bend and unbend the fingers. As you can see, the structure of the upper limbs of a person is quite complex, but thanks to this they are distinguished by their mobility.
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