Structure

How the shoulder blade is attached to the human skeleton. Movement of the scapula and collarbone. Connection of the bones of the upper limb. Connection of the bones of the shoulder girdle

Connection of the bones of the upper limb. Connection of the bones of the shoulder girdle

Clavicle connection

The clavicle is the only bone that connects the girdle of the upper limb to the bones of the body. Its sternal end is inserted into the clavicular notch of the sternum, forming the articulatio sternocla viculars, and has a saddle shape (Fig. 121). Thanks to the discus articularis, which is the transformed os episternale of lower animals, a spherical joint is formed. The joint is strengthened by four ligaments: the interclavicular ligament (lig. interclaviculare) is located above - it passes over the jugular notch between the sternal ends of the clavicle; from below, the costoclavicular ligament (lig. costoclavicular) is better developed than others. It starts from the collarbone and attaches to the 1st rib. There are also anterior and posterior sternoclavicular ligaments (ligg. sternoclavicularia anterius et posterius). When the belt of the upper limb is displaced, movements are carried out in this joint: along the vertical axis - forward and backward, around the sagittal axis - up and down. Rotation of the clavicle around the frontal axis is possible. When combining all movements, the acromial end of the clavicle describes a circle.

The acromioclavicular joint (articulatio acromioclavicularis) connects the acromial end of the clavicle to the acromion of the scapula, forming a flat joint (Fig. 122). Very rarely (1% of cases) there is a disk in the joint. The joint is strengthened lig. acromioclaviculare, which is located on the upper surface of the clavicle and spreads to the acromion. The second ligament (lig. coracoacromiale), located between the acromial end of the clavicle and the base of the coracoid process, is away from the joint and holds the clavicle against the scapula. The movements in the joint are insignificant. Displacement of the scapula causes displacement of the collarbone.

Own ligaments of the scapula are not related to the joints and arose as a result of thickening of the connective tissue. The most well developed is the coracoacromial ligament (lig. coracoacromiale), dense, in the form of an arch, against which the large tubercle of the humerus rests when the arm is abducted by more than 90 °. The short upper transverse ligament of the scapula (lig. transversum scapulae superius) is thrown over the notch of the scapula, sometimes ossifying in old age. The suprascapular artery passes under this ligament.

The bones of the upper limb are represented by the girdle of the upper limb (scapula and collarbone) and the free upper limb (humerus, ulna, radius, tarsals, metatarsals and phalanges of the fingers, Fig. 42).

Upper limb belt (shoulder girdle) is formed on each side by two bones - the clavicle and scapula, which are attached to the skeleton of the body with the help of muscles and the sternoclavicular joint.

Collarbone is the only bone that holds the upper limb to the skeleton of the body. The clavicle is located in the upper part of the chest and is well palpable throughout. Above the clavicle are large and small supraclavicular fossae, and below, closer to its outer end - subclavian fossa. The functional significance of the clavicle is great: it puts the shoulder joint at the proper distance from the chest, causing greater freedom of movement of the limb.

Rice. 42. Skeleton of the upper limb.

Rice. 43. Clavicle: (A - top view, B - bottom view):

1-acromial end, 2-body, 3-sternal end.

Collarbone- a paired S-shaped bone, it distinguishes the body and two ends - medial and lateral (Fig. 43). The thickened medial or sternal end has a saddle-shaped articular surface for articulation with the sternum. The lateral or acromial end has a flat articular surface - the place of articulation with the acromion of the scapula. On the lower surface of the clavicle there is a tubercle (a trace of attachment of ligaments). The body of the clavicle is bent in such a way that its medial part, closest to the sternum, is convex anteriorly, and the lateral part is posteriorly.

shoulder blade(Fig. 44) is a flat triangular bone, slightly curved backwards. The anterior (concave) surface of the scapula is adjacent at the level of the II–VII ribs to the posterior surface of the chest, forming subscapular fossa. The muscle of the same name is located in the subscapular fossa. The vertical medial edge of the scapula faces the spine.

Rice. 44. Shoulder blade (back surface).

The lateral angle of the scapula, with which the upper epiphysis of the humerus articulates, ends in a shallow articular cavity having an oval shape. On the anterior surface, the articular cavity is separated from the subscapular fossa shoulder blade. Above the upper edge of the depression is supraarticular tubercle(place of attachment of the tendon of the long head of the biceps brachii). At the lower edge of the articular cavity there is infraarticular tubercle from which the long head of the triceps brachii originates. Above the neck, from the upper edge of the scapula, a curved coracoid process protruding above the shoulder joint in front.

A relatively high ridge runs along the posterior surface of the scapula, called spine of the scapula. Above the shoulder joint, the spine forms a wide process - acromion, which protects the joint from above and behind. On it is the articular surface for articulation with the clavicle. The most prominent point on the acromial process (acromial point) is used to measure the width of the shoulders. The recesses on the posterior surface of the scapula, located above and below the spine, are called, respectively. supraspinous and infraspinatus fossae and contain muscles of the same name.

Skeleton of the free upper limb formed by the bones of the shoulder, forearm and hand. The humerus is located in the shoulder area, there are two bones on the forearm - the radius and ulna, the hand is divided into the wrist, metacarpus and fingers (Fig. 42).

Brachial bone(Fig. 45) refers to long tubular bones. It consists of diaphysis and two epiphyses- proximal and distal. In children, between the diaphysis and the epiphyses, there is a layer of cartilage tissue - metaphysis which is replaced by bone tissue with age. top end ( proximal epiphysis) has a spherical articular head, which articulates with the glenoid cavity of the scapula. The head is separated from the rest of the bone by a narrow groove called anatomical neck. Behind the anatomical neck are two tubercles(apophyses) - large and small. The large tubercle lies laterally, the small one slightly anterior to it. Bone ridges go down from the tubercles (for attaching muscles). Between the tubercles and ridges there is a groove in which the tendon of the long head of the biceps brachii is located. Below the tubercles on the border with the diaphysis is located surgical neck(the site of the most frequent fractures of the shoulder).

Rice. 45. Humerus.

In the middle of the body of the bone on its lateral surface is deltoid tuberosity, to which the deltoid muscle is attached, a furrow of the radial nerve passes along the posterior surface. The lower end of the humerus is expanded and somewhat bent anteriorly ( distal epiphysis) ends on the sides with rough protrusions - medial and lateral epicondyles serving to attach muscles and ligaments. Between the epicondyles is the articular surface for articulation with the bones of the forearm - condyle. It distinguishes two parts: medially lies block, having the form of a transverse roller with a notch in the middle; it serves for articulation with the ulna and is covered by its notch; above the block are located in front coronoid fossa, behind - olecranon fossa. Lateral to the block is the articular surface in the form of a ball segment - head of condyle of humerus, serving for articulation with the radius.

Forearm bones are long tubular bones. There are two of them: the ulna, lying medially, and the radius, located on the lateral side.

Elbow bone (Fig. 46) - a long tubular bone. Her proximal epiphysis thickened, it has block tenderloin, serving for articulation with the block of the humerus. Cutaway ends ahead coronoid process, behind - ulnar. Here is located radial notch, which forms a joint with the articular circumference of the head of the radius. On the bottom distal epiphysis there is an articular circumference for articulation with the ulnar notch of the radius and medially located styloid process.

Radius (Fig. 46) has a more thickened distal end than the proximal one. At the top end it has head, which articulates with the head of the condyle of the humerus and with the radial notch of the ulna. The head of the radius is separated from the body neck, below which the radial tuberosity- site of attachment of the biceps brachii muscle. At the lower end are articular surface for articulation with the scaphoid, lunate and triquetral bones of the wrist and elbow notch for articulation with the ulna. The lateral edge of the distal epiphysis continues into styloid process.

Hand bones(Fig. 47) are divided into the bones of the wrist, metacarpus and the bones that make up the fingers - the phalanx.

Rice. 47. Brush (back surface).

Wrist is a collection of eight short spongy bones arranged in two rows, each of four bones. Proximal or first row of the wrist, closest to the forearm, is formed, if counted from the thumb, by the following bones: scaphoid, lunate, trihedral and pisiform. The first three bones, connecting, form an elliptical, convex articular surface towards the forearm for articulation with the radius. The pisiform bone is sesamoid and does not participate in articulation. Distal or second row of the wrist consists of bones: trapezium, trapezius, capitate and hamate. On the surfaces of each bone there are articular areas for articulation with neighboring bones. On the palmar surface of some bones of the wrist there are tubercles for attachment of muscles and ligaments. The bones of the wrist in their totality represent a kind of arch, convex on the back and concave on the palmar. In humans, the bones of the wrist are firmly reinforced with ligaments, which reduce their mobility and increase strength.

metacarpus It is formed by five metacarpal bones, which are short tubular bones and are named in order from 1 to 5, starting from the side of the thumb. Each metacarpal has base, body and head. The bases of the metacarpal bones articulate with the carpal bones. The heads of the metacarpal bones have articular surfaces and articulate with the proximal phalanges of the fingers.

Finger bones - small, short tubular bones lying one after another, called phalanges. Each finger is made up of three phalanges: proximal, middle and distal. The exception is the thumb, which has proximal and distal phalanges. Each phalanx has a middle part - the body and two ends - proximal and distal. At the proximal end is the base of the phalanx, and at the distal end is the head of the phalanx. At each end of the phalanx there are articular surfaces for articulation with adjacent bones.

Joints of the bones of the girdle of the upper limb (Table 2). The belt of the upper limb is connected to the skeleton of the body through sternoclavicular joint; at the same time, the clavicle, as it were, moves the upper limb away from the chest, thereby increasing the freedom of its movements.

sternoclavicular joint(Fig. 48) formed sternal end of clavicle and clavicular notch of sternum. Located in the joint cavity articular disc. The joint is strengthened bundles: sternoclavicular, costoclavicular and interclavicular. The joint is saddle-shaped in shape, however, due to the presence of a disk, movements it takes place around three axes: around the vertical - the movement of the clavicle back and forth, around the sagittal - raising and lowering the clavicle, around the frontal - rotation of the clavicle, but only when flexing and unbending in the shoulder joint. Along with the clavicle, the scapula also moves.

acromioclavicular joint(Fig. 49) flat in shape with little freedom of movement. This joint is formed by the articular surfaces of the acromion of the scapula and the acromial end of the clavicle. The joint is strengthened by powerful coracoclavicular and acromioclavicular ligaments.

Rice. 48. Sternoclavicular joint (front view, on the left

the side of the joint is opened by a frontal incision):

1-clavicle (right), 2-anterior sternoclavicular ligament, 3-interclavicular ligament, 4-sternal end of the clavicle, 5-intraarticular disc, 6-first rib, 7-costoclavicular ligament, 8-sternocostal joint ( 11th rib), 9th intraarticular sternocostal ligament, 10th cartilage of the 11th rib, 11th synchondrosis of the sternum handle, 12th radial sternocostal ligament.

Rice. 49. Acromioclavicular joint:

1-acromial end of the clavicle; 2-acromio-clavicular ligament;

3-coracoclavicular ligament; 4-acromion of the scapula;

5-coracoid process; 6-coracoid-acromial ligament.

table 2

Major joints of the upper limb

Joint name	articulating bones	Joint shape, axis of rotation	Function
sternoclavicular joint	Sternal end of clavicle and clavicular notch of sternum	Saddle-shaped (there is an intraarticular disk). Axes: vertical, sagittal, frontal	Movements of the clavicle and the entire girdle of the upper limb: up and down, forward and backward, circular motion
shoulder joint	The head of the humerus and the articular cavity of the scapula	Globular. Axes: vertical, transverse, sagittal	Movements of the shoulder and the entire free upper limb: flexion and extension, abduction and adduction, supination and pronation, circular motion
Elbow joint (complex): 1) ulnar humerus, 2) glenohumeral joint, 3) proximal radioulnar joint	Humeral condyle, trochlear and radius notches of ulna, head of radius	blocky. Axes: transverse, vertical	Flexion and extension, pronation and supination of the forearm
Wrist joint (complex)	Carpal articular surface of the radius and first row of carpal bones	Ellipsoid. Axes: transverse, sagittal.	Flexion and extension, adduction and abduction, pronation and supination (simultaneously with the bones of the forearm)

The scapula moves up and down, back and forth. The scapula can rotate around the sagittal axis, while the lower angle is displaced outward, as happens when the arm is raised above the horizontal level.

Joints in the skeleton of the free part of the upper limb represented by the shoulder joint, elbow, proximal and distal radioulnar joints, the wrist joint and the joints of the skeleton of the hand - the midcarpal, carpometacarpal, intermetacarpal, metacarpophalangeal and interphalangeal joints.

Rice. 50. Shoulder joint (frontal section):

1-capsule of the joint, 2-articular cavity of the scapula, 3-head of the humerus, 4-articular cavity, 5-tendon of the long head of the biceps of the shoulder, 6-articular lip, 7-lower torsion of the synovial membrane of the joint.

shoulder joint(Fig. 50) connects the humerus, and through it the entire free upper limb with the girdle of the upper limb, in particular with the scapula. The joint is formed head of humerus and glenoid cavity of the scapula. Around the circumference of the cavity is a cartilaginous articular lip, which increases the volume of the cavity without reducing mobility, and also softens the jolts and tremors when the head moves. The articular capsule is thin and large in size. It is strengthened by the coracobrachial ligament, which comes from the coracoid process of the scapula and is woven into the joint capsule. In addition, fibers of the muscles passing near the shoulder joint (supraspinatus, infraspinatus, subscapular) are woven into the capsule. These muscles not only strengthen the shoulder joint, but also pull its capsule when moving in it, protecting it from infringement.

Due to the spherical shape of the articular surfaces, in the shoulder joint, movement around three mutually perpendicular axes: around the sagittal (abduction and adduction), transverse (flexion and extension) and vertical (pronation and supination). Circular movements (circumduction) are also possible. Flexion and abduction of the arm is possible only up to shoulder level, since further movement is inhibited by the tension of the articular capsule and the emphasis of the upper end of the humerus against the acromion. Further raising of the arm is carried out due to movements in the sternoclavicular joint.

elbow joint(Fig. 51) - a complex joint formed by a joint in a common capsule of the humerus with the ulna and radius. There are three articulations in the elbow joint: humeroulnar, humeroradial, and proximal radioulnar.

blocky humeroulnar joint form a block of the humerus and a block-shaped notch of the ulna (Fig. 52). Globular humeroradial joint make up the head of the condyle of the humerus and the head of the radius. Proximal radioulnar joint connects the articular circumference of the head of the radius with the radial notch of the ulna. All three joints are enclosed in a common capsule and have a common articular cavity, and therefore are combined into one complex elbow joint.

The joint is reinforced with the following ligaments (Fig. 53):

- ulnar collateral ligament, running from the medial epicondyle of the shoulder to the edge of the trochlear notch of the ulna;

- radial collateral ligament, which starts from the lateral epicondyle and is attached to the radius;

- annular ligament of radius, which covers the neck of the radius and is attached to the ulna, thus fixing this connection.

Rice. 52. Shoulder-ulnar joint (vertical section):

4-block notch of the ulna, 5-coronal process of the ulna.

Rice. 53. Ligaments of the elbow joint:

1-articular capsule, 2-ulnar collateral ligament, 3-beam collateral ligament, 4-ring ligament of the radius.

In the complex elbow block joint, flexion and extension, pronation and supination of the forearm are carried out. The shoulder joint provides flexion and extension of the arm at the elbow. Pronation and supination occur due to the rotational movement of the radius around the ulna, carried out simultaneously in the proximal and distal radioulnar joints. In this case, the radius rotates along with the palm.

The bones of the forearm are interconnected by combined joints - proximal and distal radioulnar joints, that function simultaneously (combined joints). Throughout the rest of their length, they are connected by an interosseous membrane (Fig. 19). The proximal radioulnar joint is included in the capsule of the elbow joint. Distal radioulnar joint rotary, cylindrical shape. It is formed by the ulnar notch of the radius and the articular circumference of the head of the ulna.

wrist joint(Fig. 54) is formed by the radius and the bones of the proximal row of the wrist: scaphoid, lunate and trihedral, interconnected by interosseous ligaments. The ulna does not reach the surface of the joint; between it and the bones of the wrist is the articular disc.

By the number of bones involved, the joint is complex, and by the shape of the articular surfaces it is ellipsoidal with two axes of rotation. In the joint, flexion and extension, abduction and adduction of the hand are possible. Pronation and supination of the hand occurs along with the same movements of the bones of the forearm. Movements in the wrist joint are closely related to movements in mid-carpal joint, which is located between the proximal and distal rows of carpal bones, excluding the pisiform bone.

Rice. 54. Joints and ligaments of the hand (back surface):

4-articular disc, 5-carpal joint, 6-mid-carpal joint,

7-intercarpal joints, 8-carpo-metacarpal joints, 9-intercarpal joints, 10-metacarpal bones.

Joints of the bones of the hand. There are six types of joints in the hand: mid-carpal, inter-carpal, carpo-metacarpal, inter-metacarpal, metacarpophalangeal and interphalangeal joints (Fig. 54).

Mid-carpal joint, having an S-shaped joint space, is formed by the bones of the distal and proximal (except for the pisiform bone) rows of the wrist. The joint is functionally integrated with the wrist joint and allows to slightly expand the degree of freedom of the latter. Movements in the mid-carpal joint occur around the same axes as in the wrist joint (flexion and extension, abduction and adduction). However, these movements are inhibited by ligaments - collateral, dorsal and palmar.

Intercarpal joints connect the lateral surfaces of the carpal bones of the distal row to each other and the connection is strengthened by the radiant ligament of the wrist.

Carpometacarpal joints connect the bases of the metacarpal bones with the bones of the distal row of the wrist. With the exception of the articulation of the trapezius bone with the metacarpal bone of the thumb (I) finger, all carpometacarpal joints are flat, their degree of mobility is small. The connection of the trapezoid and I metacarpal bones provides significant mobility of the thumb. The carpometacarpal joint capsule is strengthened by the palmar and dorsal carpometacarpal ligaments, so the range of motion in them is very small.

Metacarpal joints flat, with little movement. They are formed by the lateral articular surfaces of the bases of the metacarpal bones (II-V), strengthened by the palmar and dorsal metacarpal ligaments.

Metacarpophalangeal joints ellipsoid, connect the bases of the proximal phalanges and the heads of the corresponding metacarpal bones, strengthened by collateral (lateral) ligaments. These joints allow movement around two axes - in the sagittal plane (abduction and adduction of the finger) and around the frontal axis (flexion-extension).

Joint of the thumb has a saddle shape, abduction and adduction to the index finger, opposition of the finger and reverse movement, circular movements are possible in it.

Interphalangeal joints block-shaped, connect the heads of the superior phalanges with the bases of the inferior ones, flexion and extension are possible in them.

The musculoskeletal system consists of bones, joints, ligaments and muscle tissue. Together they work as a single system. The skeleton includes various departments. Among them are: the cranium, belts with attached limbs.

The shoulder blade is an element of the upper belt. In the article we will get acquainted in detail with the structure, adjacent parts and functions of this bone.

The human skeleton consists of different types of bones: flat, tubular and mixed. They differ from each other in form, structure and function.

The shoulder blade is a flat bone. The features of its structure are such that inside there is a compact substance of two parts. Between them lies a spongy layer with bone marrow. This type of bone provides reliable protection for internal organs. In addition, many muscles are attached to their smooth surface with the help of ligaments.

Anatomy of the human scapula

What is a spatula? It is an integral part of the upper limb belt. These bones provide a connection between the humerus and the clavicle, and are triangular in external shape.

It has two surfaces:

anterior costal;
dorsal, in which the spine of the scapula is located.

Awn - a protruding element in the form of a ridge, passing through the dorsal plane. It rises from the median edge to the lateral angle and ends with the acromion of the scapula.

Interesting. Acromion is a bone element that forms the highest point in the shoulder joint. Its process has a triangular shape and becomes flatter towards the end. It is located on top of the glenoid cavity, to which the deltoid muscles are attached.

There are three edges in the bone:

upper with a hole for vessels with nerves;
middle (medial). The edge lies closest to the spine, otherwise called the vertebral;
axillary - more extensive than the rest. It is formed by small bulges on the superficial muscle.

Among other things, the following angles of the scapula are distinguished:

acromial process

upper;
lateral;
lower.

The lateral angle is located separately from the rest of the elements. This is due to a narrowing in the bone - the neck.

In the space between the neck and the depression, the coracoid process runs from the upper edge. The name was given to him by analogy with the beak of a bird.

The photo shows the acromial process.

Bundles

The connection of the parts of the shoulder joint occurs with the help of ligaments. There are three in total:

Coracoacromial ligament. Formed in the form of a plate, shaped like a triangle. It extends from the anterior apex of the acromion to the coracoid process. This ligament forms the arch of the shoulder joint.
Transverse ligament of the scapula, located on the dorsal surface. It serves to connect the articular cavity and the body of the acromion.
superior transverse ligament uniting the edges of the cutout. Represents a bundle, if necessary, ossifies.

muscles

The pectoralis minor is attached to the coracoid process, which is necessary to move the scapula both down and forward or to the side, as well as a short element of the biceps.

The long element of the biceps is attached to the bulge above the glenoid cavity. The biceps muscle is responsible for flexing the shoulder at the joint and the forearm at the elbow. The coracoid brachialis muscle is also attached to the process. It is connected to the shoulder and is responsible for its lifting and small rotational movements.

The deltoid muscle is attached to the protruding part of the acromion and the clavicle. It covers the coracoid process and is attached to the humerus with a sharp part.

Muscles with the same name are attached to the subscapular, supraspinous, infraspinatal fossa. The main function of these muscles is to support the shoulder joint, which has an insufficient number of ligaments.

Nerves

Three types of nerves run through the scapula:

suprascapular;
subscapular;
dorsal.

The first type of nerve is placed along with the blood vessels.

The subscapular nerve permeates the muscles of the back (located under the scapula) with nerves. It innervates the bone and adjacent muscles, thereby providing a connection with the central nervous system.

Blade functions

The scapula in the human body performs a number of functions:

protective;
connecting;
supporting;
motor.

Find out where the blades are. They act as a connecting element of the shoulder girdle with the upper limbs and the sternum.

One of the main functions is to maintain the shoulder joint. This is due to the muscles extending from the shoulder blades.

Two processes - the coracoid and acromion protect the top of the joint. Together with muscle fibers and numerous ligaments, the scapula protects the lungs and aorta.

The motor activity of the upper belt directly depends on the scapula. It aids in rotation, shoulder abduction and adduction, and arm raises. With injuries of the scapula, the mobility of the shoulder girdle is impaired.

Detailed structure of the bone of the scapula in the photo.

Conclusion

A wide, paired bone called the scapula is an important component of the human shoulder girdle. Due to its shape, it performs many functions, including protective. In addition, it provides full-fledged work of the upper belt - in particular, the shoulder joint.

On all sides, the shoulder blade is surrounded by muscles that fix and set the shoulder in motion. It works only thanks to the pectoral and dorsal muscles.

Shoulder blade, scapula represents a flat triangular bone adjacent to the posterior surface of the chest in the space from the II to VII ribs. According to the shape of the bone, three edges are distinguished in it: medial, facing the spine, margo medialis, lateral, margo lateralis, and top, margo superior, on which is the notch of the scapula, incisura scapulae.

The listed edges converge with each other at three angles, of which one is directed downward ( lower corner, angulus inferior), and the other two ( upper, angulus superior, and lateral, angulus lateralis) are located at the ends of the upper edge of the scapula. The lateral angle is significantly thickened and is provided with a slightly deepened, laterally standing articular cavity, cavitas glenoidalis. The edge of the glenoid cavity is separated from the rest of the scapula by interception, or necks, collum scapulae.

Above the upper edge of the depression is tubercle, tuberculum supraglenoidale, site of attachment of the tendon of the long head of the biceps muscle. At the lower edge of the articular cavity there is a similar tubercle, tuberculum infraglenoidale from which the long head of the triceps brachii originates. The coracoid process departs from the upper edge of the scapula near the articular cavity, processus coracoideus - former coracoid.

Front, facing the ribs, surface of the scapula, facies costalis, represents a flat depression called subscapular fossa, fossa subscapularis where t. subscapularis is attached. On the back surface shoulder blades, facies dorsalis, passes spine of the scapula, spina scapulae, which divides the entire back surface into two unequal pit sizes: supraspinous, fossa supraspinata, and infraspinatus, fossa infraspinata.

spina scapulae, continuing laterally, ending acromion, acromion, hanging behind and above cavitas glenoidalis. On it is the articular surface for articulation with the clavicle - facies articularis acromi.

The scapula on the posterior radiograph has the appearance of a characteristic triangular formation with three edges, corners and processes. On margo superior, at the base of the coracoid process, it is sometimes possible to catch tenderloin, incisura scapulae, which can be mistaken for a focus of bone destruction, especially in cases where, due to senile calcification ligamentum transversum scapulae superius this notch turns into a hole.

Ossification. By the time of birth, only the body and spine of the scapula consist of bone tissue. On radiographs in the 1st year, an ossification point appears in the coracoid process (synostosis at 16-17 years old), and at the age of 11-18 years additional in the corpus scapulae, in the epiphyses (cavitas glenoidalis, acromion) and apophyses (processus coracoideus, margo medialis , angulus inferior).

The lower angle before the onset of synostosis seems to be separated from the body by a line of enlightenment, which should not be mistaken for a break line. The acromion ossifies from multiple ossification points, one of which can be preserved for life as an independent bone - os acro-miale; it can be mistaken for fragments. Complete synostosis of all nuclei of ossification of the scapula occurs at the age of 18-24 years.

Shoulder blades, upper limbs, hands.
What are the functions of the scapula (shoulders)?
Human hands perform many different movements. The arms are not as strong as the lower limbs, but they are capable of a variety of manipulations with which we can explore and learn about the world around us. The upper limb consists of four segments: the shoulder girdle, shoulder, forearm and hand. The skeleton of the shoulder girdle is formed by the clavicle and shoulder blades, to which the muscles and the upper part of the sternum are attached. Through the joint, one end of the clavicle is connected to the upper part of the sternum, the other to the shoulder blade. On the scapula is located the articular cavity - a pear-shaped depression, into which the head of the humerus enters. Shoulders can be lowered, raised, retracted back and forth, i.e. shoulders provide the maximum range of motion of the upper limbs.
The structure of the hand
The shoulders and hands are connected by means of the humerus, ulna and radius bones. All three bones are connected to each other with the help of joints. At the elbow joint, the arm can be bent and extended. Both bones of the forearm are connected movably, therefore, during movement in the joints, the radius rotates around the ulna. The brush can be rotated 180 degrees!
The structure of the brush
The carpal joint connects the hand to the forearm. The hand consists of a palm and five protruding parts - fingers.
The arm is attached to the body through the bones of the shoulder girdle, joints and muscles. Consists of 3 parts: shoulder, forearm and hand.
Shoulder blades, upper limbs, hands includes 27 small bones. The wrist consists of 8 small bones connected by strong ligaments. The bones of the wrist, articulating with the bones of the metacarpus, form the palm of the hand. Attached to the bones of the wrist are 5 bones of the metacarpus. The first metacarpal is the shortest and flattest. It connects to the bones of the wrist through a joint, so a person can freely move his thumb, move it away from the rest. The thumb has two phalanges, the other fingers have three.
Muscles of the shoulder girdle, arms and hands
The muscles of the arm are represented by the muscles of the shoulder, forearm and hand. Most of the muscles that move the hands and fingers are located in the forearm. Most of them are long muscles. With the participation of the muscles of the tendon, located near the bones of the wrist, perform a flexion-extensor function. Tendons are firmly held by ligaments and connective tissue. Muscle tendons run through canals. The walls of the channels are lined with a synovial membrane, which ends at the tendons and forms their synovial sheaths. The fluid in the vagina acts as a lubricant and allows the tendons to glide freely.
Biceps brachii (biceps)
The biceps brachii (biceps) is connected to the forearm by ligaments and tendons. The upper part of the muscle is divided into two heads, which are attached to the shoulder blade by means of tendons. At the site of their attachment is a synovial bag. The main function of the biceps of the shoulder performs when bending and raising the arm, therefore, in people doing hard physical work or actively involved in sports, these muscles are very well developed.
Triceps brachii (triceps)
The bundles of all three parts of the muscle are connected into one and pass into the tendon. At the point where the muscle passes into the tendon, there is a synovial bag (Latin bursa olecrani). The triceps muscle, located on the back of the shoulder, and the deltoid muscle (lat. T. deltoideus), located above the shoulder joint, are attached to the shoulder blade. The shoulder blade is supported by the levator muscle. Other muscles of the shoulder girdle are located in the chest and neck.