Skeleton of the shoulder girdle. Connection of the bones of the shoulder girdle

The upper limb girdle (shoulder girdle) is a set of bones and muscles that provide support and movement of the arms. It covers the area from the shoulder joint to the elbow. The bone structure consists of the clavicle, shoulder blades and humerus, followed by the forearm and hand.

The bones of the shoulder girdle connect the acormioclavicular joints (the bony connection between the acromion and the collarbone). The shoulder girdle is attached to the skeleton using the sternoclavicular joints, muscles and ligaments that hold the scapula and upper limb.

Shoulder injuries are common, especially among professional athletes and people who do heavy physical work with their hands. Pathologies are manifested by pain, crepitus, and deformation. Conservative treatment is usually carried out, but in severe cases surgery is necessary.

Shoulder anatomy

Not all people know how many bones make up the shoulder girdle. The skeleton of the upper limb girdle is formed by the following bones: 2 shoulder blades, 2 clavicles, humerus.

The scapula is a triangle-shaped bone that is located on the back surface of the body. The clavicle is a paired bone that is curved along its long axis in the shape of the letter S. It is located horizontally along the front and upper surface of the body. The shoulder girdle includes the humerus.

A diagram of the bones of the shoulder girdle is presented below.

Bones of the shoulder girdle

Some people are interested in the question of what type of bones of the upper limb girdle are. The scapula is a flat bone, while the clavicle and humerus are tubular.

The ligamentous apparatus of the shoulder consists of the acromioclavicular joint and the shoulder joint. The acromioclavicular joint is strengthened by the coracoclavicular ligament. The scapula is supported by the coracoacromial and superior transverse ligaments. The shoulder joint is strengthened by the coracobrachial ligament, as well as the fibers of the supraspinatus, infraspinatus, subscapularis, and teres minor muscles.

Thanks to the muscles, tendons and ligaments, the upper limb has the correct position, it is strengthened and is capable of performing a variety of movements.

The muscles of the shoulder girdle include: motors, coordinators, stabilizers of the scapula. The motor muscles include the deltoid, latissimus dorsi, and pectoralis major. They are involved in performing basic arm movements (extension, adduction, abduction, rotation). The group of coordinating muscles may include: subscapularis, supraspinatus, infraspinatus, teres minor. They are necessary to ensure that movements in the shoulder are coordinated. Scapula stabilizers include the trapezius, rhomboid major, rhomboid minor, serratus anterior, pectoralis minor, and levator scapulae muscles. They regulate the movement of the shoulder blades.

What muscles are included in the shoulder girdle: anatomy and structure

The peculiarity of the group is that the shoulder muscles included in it surround the joint and ensure its movement. In anatomy, the shoulder girdle includes:

1. Deltoid.
2. Small chest.
3. Subscapular.
4. Large and small round.
5. Supraspinatus.
6. Infraspinatum.

Structure and functions of the clavicle

The clavicle is the only bone in the human body that connects the skeleton to the upper limb. Tubular bone mainly consists of spongy substance. It has a horizontal position and runs along the upper edge of the chest. The clavicle consists of a body and 2 ends:

• The medial (sternal) end connects to the sternum.
• Lateral (acromial) faces the collarbone.

The clavicle consists of a body and 2 ends

The medial end, like the sternum, has a convex curve forward, and its other part is curved backward. The middle part of the bone is slightly compressed from top to bottom. On its lower surface there is an opening through which blood vessels and nerves pass. On the lower surface of the medial end there is a depression to which the ligament connecting the clavicle and the cartilage of the first rib is attached. At the humeral end there is a cone-shaped tubercle and a trapezoidal line. Closer to the lateral end of the lower surface of the body of the clavicle there is a recess for the attachment of the subclavian muscle.

The front and top parts of the bone are smooth, and the lower surfaces to which the muscles and ligaments are attached have roughness in the form of tubercles and lines. On the inner surface of the thick medial end there is a large oval joint - this is the junction of the clavicle with the sternum. The lateral end is wider than the medial end, but not as thick. Above its lower surface is the acromioclavicular joint, which connects the collarbone to the bony outgrowth of the scapula (acromion).

The bony joints of the acromioclavicular joint are oblique, flat, and elliptical in shape. There is a dense fibrous membrane around it, which is strengthened by ligaments. The sternoclavicular joint is also surrounded by a wide fibrous membrane and 3 powerful ligaments. This joint is involved in movements along axes that are perpendicular to each other.

The collarbone performs a supporting function, since the scapula and arm are attached to it. In addition, the bone connects the upper limb to the skeleton, providing it with a wide range of movements. Together with the scapula and muscles, the clavicle transmits forces that affect the arms and the rest of the skeleton. In addition, the bone protects blood, lymphatic vessels, and nerves that are located between the neck and upper limb from pinching.

Clavicle injuries

As you can see, the collarbone performs important functions, but it bears a large load, so it is susceptible to various injuries:

Dislocation of the acromial end of the clavicle with ligament rupture

• Fracture. In most cases, the fracture occurs in the middle of the bone body. There is a left and right clavicle, usually one of them is injured, a bilateral fracture rarely occurs. A fracture most often occurs when a person falls on their arm or receives a direct blow. There is a risk of injury to the fetus' collarbone as it passes through the birth canal. After a fracture of the collarbone, the arm lengthens, the limb in the collarbone area becomes deformed, and the victim cannot lift it.
• Dislocation of the acromial end. The articular surfaces are displaced after a fall on the shoulder. Features of the injury: after the impact, the scapula is pushed down, the collarbone is not so mobile, so it does not move behind it, as a result, the ligaments connecting the bones are torn, and the acromioclavicular joint is dislocated. The injury is manifested by elongation of the arm, swelling and deformation. When you press on the collarbone, it falls into place; after the pressure stops, it rises again.
• Osteolysis of the clavicle. This is a rare disease characterized by complete destruction (resorption) of bone without replacement by other tissue. The exact causes of the pathology are not known, but doctors suggest that it is associated with autoimmune diseases of bone tissue. The only symptom is slowly healing fractures.

If a clavicle injury is suspected, MSCT (multispiral computed tomography) is prescribed - this is a modern study that uses X-rays and conducts a multi-slice scan of the clavicle. Multislice CT allows for qualitative and detailed examination of morphological changes in bones and surrounding tissues.

For ordinary clavicle fractures, conservative treatment is carried out, and the patient is given a fixing bandage. If fragments are displaced and soft tissue is damaged, surgery is performed, and bone fragments are connected using special plates, knitting needles or rings. The rehabilitation period plays an important role, when the patient is taught to move the injured arm again.

Anatomical structure and functions of the scapula

A paired triangular bone is located on the back surface of the body on both sides of the spine. Its base is at the top and the pointed end is at the bottom. It is a flat, wide bone that is slightly curved backwards.

The scapula is a paired triangular bone

The scapula consists of an anterior (costal) and posterior (dorsal) surface.

Anatomy of the posterior part of the scapula:

• The spine is a protruding plate of bone that crosses ¼ of the bone and separates the supra- and infraspinatus fossae.
• The acromion process is an elongated, triangular-shaped process at the top of the bone that ends at the spine.
• The coracoid process is the hamate bone. Which is located between the upper edge, the neck of the scapula.
• The neck is the slight narrowing that separates the rest of the scapula from the outer corner.
• Body of the scapula.
• Inner edge of the shoulder blade.
• External corner.

The structure of the scapula in front is simple; it has a wide fossa to which the subscapularis muscle is attached. The inside of the cavity is covered with ridges to which tendons and muscle fibers are attached. In the upper part of the socket there is a transverse depression where the scapula bends along a line that runs at an angle of 90° through the middle of the glenoid fossa, which includes the head of the humerus.

There are 3 angles:

• The superior angle is formed by the superior and medial borders of the bone. It is thin, has a smooth surface and a rounded shape, and fibers of the muscle that elevate the scapula are attached to it.
• Lower. The lateral border of the scapula forms a lower angle with the medial border. This is the lowest thick section of bone with a rough texture. The teres major and several fibers of the latissimus dorsi muscle are attached to it posteriorly.
• Lateral. This is the thickest part of the scapula and contains the articular socket that connects to the humerus. At the apex of the lateral angle is the supraglenoid tuberosity, to which the head of the biceps is attached.

There are 3 edges of the scapula:

• The top one is considered the thinnest and shortest. It has a concave shape, occupies the area from the upper angle to the coracoid process.
• Lateral - the thickest edge of the scapula. It starts from the lower edge of the articular socket, passes down and back to the lower corner of the bone.
• The medial edge is the longest edge, which occupies the area from the upper to the lower corner of the bone.

Thanks to the articulations, the scapula connects the humerus and collarbone, providing mobility to the upper limb. The paired bone protects important organs and blood vessels from damage. And also the scapula, together with the muscles, performs a motor function, it allows you to rotate, abduct (to the side, back, forward), and understand the arms.

Upper limb movements

Movements of the upper limb belt

The upper limb belt not only serves as a support for the upper limb, but also increases its mobility with its movements. The movements of the upper limb girdle involve not only the muscles that have their attachment points here, but also the pectoralis major muscle and the latissimus dorsi muscle (via the humerus).

All the variety of complex movements of the upper limb belt can be decomposed into simple motor acts:

1. movements forward and backward (the first is accompanied by abduction of the scapula from the spinal column, and the second by its adduction);
2. raising and lowering the scapula and clavicle;
3. movement of the scapula by the lower angle inward and outward;
4. circular movement of the outer end of the clavicle and scapula.

The forward movement of the upper limb belt is produced by the following muscles:

1. pectoralis major muscle (through the humerus);
2. pectoralis minor muscle;
3. serratus anterior muscle.

The movement of the upper limb belt back is carried out:

1. trapezius muscle,
2. rhomboid major and minor muscles,
3. latissimus dorsi muscle (through the humerus).

Raising the upper limb belt occurs with simultaneous contraction of the following muscles:

1. the upper bundles of the trapezius muscle, which pull up the outer end of the clavicle and the humeral process of the scapula;
2. levator scapulae muscle;
3. rhomboid muscles, during the decomposition of the resultant of which there is a certain component directed upward;
4. sternocleidomastoid muscle (with a fixed position of the head and neck).

To move the belt of the upper limb downwards, it is enough to relax the muscles that lift it, since at the same time it lowers under the influence of the weight of the upper limb. Its active lowering is facilitated by:

1. pectoralis minor muscle,
2. subclavian muscle,
3. lower bundles of trapezius muscle,
4. inferior teeth of the serratus anterior muscle,
5. lower bundles of the pectoralis major muscle,
6. lower bundles of the latissimus dorsi muscle.

The external rotation of the scapula by the lower angle is very important, since thanks to this movement the upper limb rises above the level of the upper limb belt. It occurs as a result:

1. the action of a pair of forces formed by the upper and lower parts of the trapezius muscle;
2. contraction of the serratus anterior muscle. Rotation of the scapula by the lower angle inward occurs under the influence of gravity of the upper limb. This movement is helped by:
3. pectoralis major and minor muscles,
4. lower part of the rhomboid major muscle,
5. latissimus dorsi muscle (through the humerus).

The circular movement of the upper limb girdle occurs as a result of alternate contraction of all the muscles acting on it.

Upper limb shoulder movements

The movements of the free upper limb are determined by the permissible degrees of freedom in its joints. No matter how complex and varied the movements of the upper limb are, all of them can be considered as a set of simple movements performed in one or another joint. In this case, movements around each axis of rotation are performed by a specific group of muscles. The following muscles are involved in shoulder movements at the shoulder joint.

Shoulder abduction : 1) deltoid muscle, 2) supraspinatus muscle.

Shoulder adduction : 1) pectoralis major, 2) latissimus dorsi, 3) infraspinatus, 4) teres major and minor, 5) subscapularis, 6) long head of triceps brachii, 7) coracobrachialis.

Shoulder flexion : 1) anterior deltoid, 2) pectoralis major, 3) coracobrachialis, 4) biceps brachii.

Shoulder extension : 1) posterior deltoid, 2) latissimus dorsi, 3) infraspinatus, 4) teres major and minor, 5) triceps brachii.

Shoulder pronation : 1) subscapularis, 2) pectoralis major, 3) anterior deltoid, 4) latissimus dorsi, 5) teres major, 6) coracobrachialis.

Supination

shoulder
: 1) infraspinatus muscle, 2) teres minor, 3) posterior part of the deltoid muscle.
Circular movement of the shoulder occurs with alternate contraction of all the muscles located around the shoulder joint.

Pathologies of the scapula

When the scapula is injured, the quality of life decreases; people are not able to care for themselves or perform physical work. The shoulder blades can be damaged by a fall on your back, shoulder or arm, a direct blow, an accident, or a work-related injury.

There is a possibility of bone fracture in the following areas: neck, glenoid, spine, coracoid process, acromion, superior or inferior angle. And longitudinal, transverse or multi-fragmented damage is also possible.

When a fracture occurs, the “Comolli triangle” appears - this is a swelling in the shape of a triangle. On palpation, the pain in the damaged area intensifies. A displaced fracture is accompanied by a crunching sound from bone fragments. In case of intra-articular injury, the shoulder and arm are raised. Blood accumulates in the cavity of the bone connection, so the size of the shoulder increases. When the neck is damaged, the shoulder drops slightly, the acromion protrudes forward, and the coracoid process moves slightly back. With an open fracture, a wound appears through which bone fragments are visible.

Dislocation of the scapula is a rare occurrence. The injury occurs if a person makes a strong jerk with his arm or shoulder, as a result, the bone is displaced. After a dislocation, the coracoid process of the scapula protrudes through the skin, causing sharp pain that intensifies with movement.

Bursitis is an inflammation of the synovial (periarticular) bursae of the shoulder joint. Typically, the disease develops against the background of infection, injury, or an autoimmune disease. With bursitis, pain occurs, the damaged area turns red, swells, a feeling of numbness appears, and it is difficult for the victim to move his arm.

Multi-slice computed tomography will help detect scapular pathologies.

For ordinary fractures, a special splint is placed on the arm on the damaged side, which must be worn for 4 weeks. Then physiotherapy and massage are prescribed, the patient must develop the limb with the help of special exercises. For intra-articular injuries, surgery is indicated.

Bursitis is treated with the use of NSAIDs, steroid hormones, antibacterial agents, analgesics, chondroprotectors, and vitamin-mineral complexes.

Functions of the muscles of the shoulder girdle

Table describing the main functions:

Anatomy of the humerus

The humerus is a wide, long tubular structure. It is part of the movable upper limb, unites the ulna, radius, and hand with the human skeleton. Around the humerus there are muscles, nerve trunks, and lymphatic vessels.

Brachial bone

The shoulder structure has the following structure:

• The body of the bone (diaphysis), which is located between the epiphyses.
• Metaphysis is the section of bone that is adjacent to the epiphyseal plate.
• Epiphysis – upper proximal, lower distal end of the structure.
• Apophysis is a process of bone next to the epiphysis, to which muscle fibers are attached.

At the proximal end of the humerus is the smooth round head of the humerus, the articular cavity of the scapula, which form the shoulder joint. Next comes the anatomical neck - this is a narrow groove between the head and the body of the shoulder. Just below the neck there are 2 muscle tubercles (large and small), to which the rotator cuff muscles are attached. Under the tubercles it narrows again, forming a body. On its outer part, almost in the middle, there is a deltoid tuberosity, to which the fibers of the muscle of the same name are attached. On its posterior edge there is a groove of the radial nerve in the form of a flat, gentle groove.

The lower edge of the bone is wide, bent anteriorly, muscle fibers are attached to it, and it also participates in the structure of the elbow joint. The joint consists of the condyle of the humeral structure with the bones of the forearm. The inner edge of the condyle is the block of the humerus that connects to the ulnar structure. The head of the condyle, together with the radial structure, forms the humeroradial articulation. Above the condylar head is the radial fossa. On both sides of the trochlea are the ulnar and coronoid fossa. The humerus has lateral and medial epicondyles (rough convexities) on the outside and inside. On the surface of the medial process there is a groove with the ulnar nerve trunk.

The functions of the humerus, despite its simple structure, are important. It increases the swing when a person moves his arm. This structure helps maintain balance when the center of gravity shifts during walking. It helps determine the correct support of a person on the upper limbs in various specific body positions (for example, while climbing stairs).

BONES OF THE SHOULDER GIRLD AND SHOULDER

Bones of the shoulder girdle

The upper limb girdle includes the scapula and collarbone.

The scapula is a flat, triangular-shaped bone located on the back surface of the body. It has three edges: superior, medial

and
lateral
and between them there are three angles:
lateral
, inferior and superior.
The lateral
angle is greatly thickened and has a glenoid cavity, which serves to articulate the scapula with the head of the humerus. The narrowed place adjacent to the cavity is called the neck of the scapula. Above and below the glenoid cavity there are tubercles—supraarticular and subarticular. The lower angle is located approximately at the level of the upper edge of the eighth rib and can be easily felt under the skin. The upper corner faces inward and upward.

The costal surface of the scapula faces the chest; this surface is somewhat concave and forms the subscapular fossa. The dorsal surface of the scapula is convex and has a spine running from the inner edge of the scapula to its outer corner. The spine divides the dorsal surface of the scapula into two fossae: supraspinatus and infraspinatus, in which the muscles of the same name are located. The spine of the scapula is easily palpable under the skin. Outwardly it passes into the humeral process of the scapula ( acromion

), which is located above the shoulder joint. Its outer extreme point serves as an identification point when determining the width of the shoulders. In addition to the acromion, the scapula has a forward-facing coracoid process, which serves to attach muscles and ligaments.

The clavicle is an S-shaped tubular bone curved along its long axis. It is located horizontally in front and above the chest on the border with the neck, connecting with the medial

the sternal end is with the sternum, and
the lateral
end is acromial with the scapula. The collarbone is located directly under the skin and can be easily felt along its entire length. With its lower surface it is attached to the chest with the help of ligaments and muscles, and to the scapula through ligaments. Accordingly, on the lower surface of the clavicle there are roughnesses in the form of a tubercle and a line.

Bones of the humerus of the free upper limb

The shoulder contains only one bone, the humerus. The humerus is a typical tubular bone. Its body in the upper section has a rounded cross-section, and in the lower section it has a triangular shape.

At the upper end ( ) of the humerus is the head of the humerus. It has the shape of a hemisphere, faces the scapula and carries an articular surface to which the so-called anatomical neck of the humerus adjoins. Outside the neck there are two tubercles that serve for muscle attachment: the greater tubercle, facing outward, and the lesser tubercle, facing anteriorly. From each of the tubercles there is a ridge running downwards. Between the tubercles and ridges there is a groove in which the tendon of the long head of the biceps brachii muscle passes. Below the tubercles is the most narrowed place of the humerus - its surgical neck.

On the outer surface of the body ( diaphysis

) of the humerus there is a deltoid tuberosity to which the deltoid muscle is attached. With the development of the deltoid muscle as a result of sports training, there is not only an increase in the deltoid tuberosity, but also an increase in the thickness of the entire compact layer of bone in this area. Along the posterior surface of the body of the humerus, a groove of the radial nerve runs spirally from top to bottom and outwards.

The lower end () of the humerus forms the condyle and has an articular surface that serves for articulation with the bones of the forearm. Medial

the part of the articular surface that articulates with the ulna is called the trochlea of ​​the humerus, and
the lateral part
that articulates with the radius is spherical in shape and is called the head of the condyle of the humerus.
Above the block in front and behind there are pits into which, when flexing and extending the forearm, the processes of the ulna enter - the coronoid (in front) and ulna (in back). These fossae are named accordingly: the anterior one is the coronoid fossa and the posterior one is the olecranon fossa. On both sides of the distal
end of the humerus there are
medial
and
lateral
epicondyles, easily palpable under the skin, especially
the medial one
, which has a groove for the ulnar nerve on its posterior side. The epicondyles serve to attach muscles and ligaments.

Shoulder injuries

Shoulder dislocation is a common occurrence that is associated with arm mobility. The displacement can be anterior, posterior, or inferior. When a dislocation occurs, the mobility of the limb is limited, pain and swelling appear. When the nerve is compressed, a feeling of numbness occurs.

A fracture most often occurs from a direct blow to the shoulder, falling backwards onto the elbows, or falling forward onto the arms. Typically, the integrity of bones is compromised in weak areas:

• Anatomical and surgical neck of the humerus.
• The area near the condyles.
• The area near the head of the humerus.
• The middle of the bone.

The injury is manifested by severe pain and impaired mobility. After some time, the shoulder swells, hematomas appear, and the damaged area becomes deformed.

Osteomyelitis is a purulent inflammation of the bone due to the penetration of microbes into the bone marrow through the blood. This disease is common because the humerus is abundantly supplied with blood. The pathological process provokes the destruction of bone tissue, as a result, fractures form without significant external influence.

Reference. Among the commonly diagnosed pathologies of the humerus are arthritis (inflammation of the joint).

Pseudarthrosis is also a common pathology. Not all patients know what it is. This is an abnormally formed joint that appears at the site of a non-union fracture of the humerus. With pathology, the functionality of the hand is impaired, but there is no pain.

Palpation and visual inspection can identify injuries and diseases of the humerus. X-rays can help differentiate a fracture from a dislocation. MRI and multi-slice computed tomography can detect malignant tumors. A multislice tomograph will help to examine the bone structure in detail and determine pathological changes.

When a dislocation occurs, a health care worker gives the victim a painkiller, compares the fragments of the joint, and then immobilizes the limb. Simple fractures are also treated conservatively. If the bone fragments are displaced, then surgery is necessary. The bone fragments are connected using knitting needles or screws, and then a Turner plaster splint is applied. If necessary, skeletal traction is performed first.

Exercise therapy will help develop the shoulder joint for flexibility. During rehabilitation, mechanotherapy and physiotherapy are indicated.

The most important

Now you know which bones form the shoulder girdle. The shoulder blades, collarbone and humerus take part in the formation of important joints, and thanks to muscles and ligaments, they provide mobility of the upper limb. Fractures of the clavicle and humerus occur more often than injuries to the scapula. This is due to the fact that the scapula is a fairly strong bone, which is protected by a thick layer of muscle. After identifying an injury, the affected limb is immobilized, and in case of complex fractures, an operation is performed to compare bone fragments. Therapeutic gymnastics and physiotherapy will help speed up recovery.