Shoulder girdle: anatomy of the skeleton and joints of the shoulders and arms, structural features, functions

The functions of the muscles of the shoulder girdle are related to the functions of the muscles of the chest and partly the back. Therefore, the distinction between the torso and the shoulder girdle is very arbitrary. As the contours of the muscles change, the contours of the back, neck and chest also change.

The muscles of the shoulder girdle include:

Pectoralis minor muscle
Brachialis muscle
Subscapularis muscle
Coracobrachialis muscle
Teres major muscle
Supraspinatus muscle
Infraspinatus muscle
Teres minor muscle

The shoulder joint is ball-and-socket. It is formed by the head of the humerus and the glenoid cavity of the scapula. This joint allows flexion (raising the arm forward) and extension (moving the arm back) of the arm in the shoulder joint, adduction (movement of the arms in a horizontal plane at shoulder level forward) and extension (movement of the arms in a horizontal plane at shoulder level back) of the arms, rotation arms in and out, abduction (to the side) and adduction (to the side of the body) of the arm.

Blade structure

The large, flat, triangle-shaped bone located on the upper back is called the scapula. This is a paired bone, the base of which goes up and the sharp end goes down on both sides of the spine. It appears to be a wide, flat structure that is slightly curved backwards.

Reference. A pair of shoulder blades at the back and a pair of clavicles at the front are needed to form the bony shoulder girdle.

Skeleton of the dorsum of the scapula:

The spine is a bony ridge that crosses the upper edge of the scapula.
The acromion is the humeral process with which the spine ends. The junction of the acromion and the clavicle constitutes the acromioclavicular junction.
The coracoid is a hook-shaped projection shaped like a bird's beak that is located on the top of the bony structure near the glenoid socket. Muscles and ligaments are attached to it.
The neck is a narrowed place that is adjacent to the glenoid cavity of the bone. This area serves to connect the articular surfaces of the scapula and shoulder; it forms the glenohumeral joint.
Body of the scapula.
Side edge.
External corner.

The anterior surface of the human scapula consists of the following elements:

Body.
The articular socket together with the head of the humerus forms the shoulder joint.
Coracoid process.

The anterior surface of the bone structure is concave, and the posterior surface is convex. The scapular muscle is attached to the anterior part.

The upper edge of the bone contains a depression in which nerve fibers and blood vessels pass. The vertebral margin is located next to the spinal column. And the lateral edge is the largest area that is formed by tubercles on the brachialis muscle.

There are 3 angles of the scapula:

The upper one has a round shape and is located on top.
The lower one has a thicker structure.
The lateral one is very thick, includes the articular cavity, which connects to the head of the humerus. It is located opposite the superior medial angle.

The lateral angle is separated from the body of the scapula by the neck.

Anatomy of the scapula

The structure of the scapula is shown above.

Recommendations

In fitness, the muscles of the upper limbs are more developed in men. This is due to the fact that women often avoid their workout, giving priority to the lower body. This distribution is considered erroneous and will lead not only to an imbalance in muscle development, but also to a deterioration in the aesthetics of the figure. Therefore, it is necessary to work out the shoulder girdle for both men and women.

Basic recommendations:

Women should give preference to multi-repetition techniques. They allow you to qualitatively work out the entire group without a pronounced increase in muscle mass (they do not spoil the figure).
for men to alternate strength (6-8 repetitions) and multi-repetition (12-16 repetitions) modes to develop strength qualities and strength endurance.
For each exercise, it is enough to perform 3 working approaches. It is advisable that the last set be a failure set or precede a muscle failure.
At the end of your workout or after 6-8 hours, it is recommended to stretch the entire area. This will increase the speed and quality of recovery. Read more about post-workout stretching →
Before each workout, a thorough warm-up should be performed. The shoulder girdle area is considered one of the most vulnerable to injury.
The load is distributed evenly (for example, an equal number of exercises for each deltoids).
Priority should be given to individual areas only if they are clearly lagging behind. Most often this concerns the posterior bundle of deltas.

Anatomy of the clavicle

The S-shaped bone, curved along its long axis, is called the clavicle. It is located horizontally on the front and upper part of the chest. This bone borders the neck. The clavicle is classified as a tubular bone, and it consists mainly of spongy substance.

The clavicle consists of a body, an outer end and an inner end

Topography of the human clavicle:

Body of the bone.
Outer end.
Inner end.

The inner end is adjacent to the manubrium of the sternum, it has a convexity that curves forward, and the other part curves backward. The middle part of the bone structure is slightly compressed from top to bottom. The nutrient foramen is located in the lower part of the clavicle. At the inner end there is a recess for the costoclavicular ligament.

The left outer end of the bone is connected to the acromion of the scapula. On this part of the bone there is a cone-shaped tubercle, as well as a trapezoid-shaped line. On the lower surface of the clavicle body, closer to the acromion, there is a recess for the attachment of the muscle of the same name.

The bone is smooth on top and rough on the bottom, with tubercles and lines. Its inner end is thicker. On its inner side there is an articular surface. The outer end is wider, but not as thick. This one often connects the clavicle to the acromion of the scapula.

Topography of the humerus

The tubular bone that is located in the upper part of the arm is called the humerus. It has a long body and widens at the ends. The upper section is round in shape, and the lower section is triangular.

The humerus bone consists of a body, upper, lower end

Topographic anatomy of the humerus:

Clavicle subluxation

The upper end (proximal epiphysis) consists of a rounded head that fits into the glenoid cavity of the scapula and forms the shoulder joint with it. Under the articular surface there is an anatomical neck. Under the neck there is a large and small tubercle, to which the muscles are attached. From both tubercles, ridges descend down the body of the bone. Between the tubercles and ridges there is a recess for the biceps tendon. The surgical neck is located under the tubercles.
The body of the bone starts from the surgical neck. Approximately in its middle (outer surface) there is a deltoid tuberosity, to which the muscle of the same name is adjacent. On the back surface there is a radial groove, which spirals downwards and then outwards. The radial nerve passes through this depression, as well as the large brachial artery, which provides blood supply to the posterior group of muscles, the humerus.
At the lower end (distal epiphysis) there are the internal and external condyles, as well as the articular surface that connects the humerus to the bones of the forearm. The trochlea of the humerus is the inner part of the articular surface that is adjacent to the ulna. The head of the condyle is the outer part that connects to the radius. Above the trochlea, in front and behind, during movement of the upper limb, the coronoid (in front) and also the olecranon (in back) processes enter. The epicondyles (internal and external) are located under the distal end of the humerus. The ulnar nerve groove is located on the posterior side of the internal epicondyle.

Muscles and also ligaments are attached to the epicondyles.

Shoulder muscle injuries

A sprain or rupture of the ligaments of the shoulder joint is one of the most common sports and everyday injuries.

Causes:

sudden movement, blow, fall on an outstretched arm;
hanging on one arm, sudden lifting of weights;
fractures - when fragments are displaced, damage to muscle and tendon fibers occurs;
incorrect execution of bench presses in a prone position or from the forearm, exercises on the horizontal bar and uneven bars.

Weakening of the muscular and ligamentous apparatus often occurs due to metabolic disorders, age-related changes, smoking, intoxication, and long-term hormonal therapy. If a sprain is left untreated, tendonitis, bursitis , and tendon problems arise.

Ligamentous apparatus

The connection between the acromion and the collarbone is called the acromioclavicular joint. It is formed by flat articulated surfaces. The joint is stabilized by the coracoclavicular ligament, which arises from the coracoid process and reaches the inferior surface of the clavicle.

Shoulder joint ligaments

The scapula has its own ligaments – the coracoacromial and superior transverse. The first looks like a triangle-shaped plate that runs from the acromion to the coracoid process of the scapula. The coracoacromial ligament forms the arch of the shoulder.

The structure of the humeral joint is simple: a spherical head and an articular recess of the scapula.

Reference. The articulating depression of the scapula is equal to 1/3 of the surface of the head. The labrum is a ring-shaped cartilaginous formation that is attached along the edge of the glenoid fossa, increasing its depth.

The articular capsule is adjacent to the anatomical neck of the shoulder. It is quite thin and large. Between the tubercles of the bony structure of the shoulder is the synovial sheath (inner layer of the capsule), which surrounds the tendon and facilitates its gliding.

Auxiliary elements of the shoulder joint capsule: coracobrachial ligament, supraspinatus, infraspinatus, subscapularis and teres minor muscles. The ligament stabilizes the joint capsule, and the muscles not only strengthen it, but also protect it from pinching.

Reference. The humeroulnar joint is formed by the humerus and ulna. The humeral joint is formed by the humerus and radius bones.

Muscles

The upper limb girdle includes the following muscles:

Deltoid. The fibers of this muscle extend from the spine, acromion, acromial end of the clavicle, and adjoin the deltoid tuberosity of the humerus. The posterior part (scapular) extends the shoulder, and the anterior (clavicular) flexes.
Supraspinatus. This anatomical structure originates from the supraspinatus fossa of the scapula and is attached to the superior portion of the greater tubercle of the humerus. The supraspinatus muscle abducts the shoulder.
Infraspinatus. It is localized in the infraspinatus recess of the scapula, and is attached to the greater tubercle of the shoulder. The infraspinatus muscle helps adduct, rotate and extend the shoulder.
Small round. It arises from the scapula and is adjacent to the greater tubercle. It allows you to rotate your shoulder outward.
Big round. It starts from the lower angle of the scapula and is attached to the crest of the lesser tubercle. Functions: adduction, internal rotation, shoulder extension.
Subscapular. It starts from the outer edge of the scapula, fills the subscapular cavity, and is attached to the lesser tubercle of the shoulder. It helps move the arm inward and bring it toward the body.

Muscles of the upper limb girdle

Classification of shoulder muscles:

The anterior group (flexors) includes the coracobrachialis, brachialis, and biceps muscles.
Posterior group (extensors): triceps and ulnaris muscles.

The structure of the muscles of the humerus:

Coracobrachial. It arises from the coracoid process and attaches under the crest of the lesser tubercle to the humerus. Responsible for bending the arm.
Shoulder. It arises from the lower two-thirds of the humerus, adjacent to the tuberosity of the elbow. Participates in flexion of the forearm.
Double-headed. The long head of the muscle comes from the supraglenoid tubercle of the scapula, and the short one comes from the coracoid process, connects with the tuberosity of the radius and the fascia of the forearm (the connective tissue membrane that covers organs, vessels and nerves). The biceps muscle flexes the shoulder, forearm, and allows you to rotate your arm from the elbow to the wrist.
Three-headed. The long head extends from the tubercle of the scapula under the joint, and the inner and outer heads arise from the posterior surface of the humerus. They are adjacent to the tendon, which is attached to the olecranon process. Helps to make extension, adduction movements of the shoulder, forearm and straighten the elbow.
Elbow. It starts from the external epicondyle of the shoulder, the ligament of Henle, as well as the fascia, and connects to the ulna in its upper part on the posterior surface. Helps extend the forearm.

All muscles in the area of the shoulder joint are located on top. Below the bony junction is the axillary depression, through which the nerves and blood vessels of the arm pass.

How to pump up and strengthen the muscles of the shoulder girdle

To pump up and give beautiful relief to your shoulders and forearms, you need to perform strength exercises .
The weight for exercise must be selected taking into account physical fitness, otherwise you can get serious injuries. You need to start with 5-7 repetitions, perform 3 approaches. The best exercises for developing the muscles of the shoulder girdle :

The close-grip bench chest press is one of the effective exercises for developing the strength of the triceps and pectoral muscles.
Bench extension with a barbell lying down. For deep muscle work, it is better to use barbells with a straight bar.
Pull-up on the horizontal bar with a neutral grip.
Lifting dumbbells from behind your head. To achieve results, the hand must be retracted as much as possible and fixed in the lower position.
Dumbbell press.
It is better to perform in a standing position, this accelerates the growth of the shoulder, pectoral muscles, deltoid muscles, and the long head of the triceps. Your arms should be straightened strictly above your head, without falling back.
Swing dumbbells in a lying position. Lie face down on the bench, toes touching the floor. Take dumbbells in your hands, bend your arms slightly at the elbows. Raise the weight, bringing your shoulder blades together.
Bent-over dumbbell raises. Tilt your body, bend your knees. Do 7 repetitions with a neutral grip - palms facing each other. Another 7 - with a reverse grip - palms facing down.

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General doctor

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To pump up your shoulders, you need to create a proper training program. The complex should include exercises for various muscle groups in the shoulder area. If you need to work specific muscles, you just need to increase the number of approaches. Before training, be sure to warm up to avoid injury. Classes should be done every other day, the muscles should rest.

Functions of the bones of the shoulder girdle

The role of the scapula in the girdle of the upper limbs is important; first of all, it ensures the mobility of the arm, connecting the humerus and collarbone.

The bones of the shoulder girdle, together with ligaments and muscles, allow various movements of the arms

Other functions of the scapula:

protective;
connecting;
stabilizing;
motor.

This bone structure protects important organs and blood vessels from damage.

Together with the muscles, the scapula provides mobility of the upper limb:

rotation;
abduction to the side, back, forward;
lifting up.

Reference. To determine the functional state of the shoulder girdle in the joint area, the volume of active (movements that a person performs) and passive (movements that a doctor performs) movements are measured. Measurements are recorded in degrees. For example, physiological movements in the shoulder joint: flexion - about 90°, extension - up to 45°, abduction - no more than 90°, abduction with the participation of the scapula can reach 180°.

Functions of the clavicle:

Support. The scapula and arm are attached to the clavicle bone. In addition, this bone connects the upper limb to the rest of the skeleton.
Transmits physical impulse from the upper limb to the axial skeleton.
Provides protection to nerves, blood and lymphatic vessels, which are located in the area between the neck and arm.

The humerus is a kind of lever, thanks to which the amplitude of arm movements increases. In addition, it helps maintain balance when the center of gravity shifts during movement.

How does movement happen?

All movements of the PP occur in the sternoclavicular joint. They are combined with simultaneous movements of the shoulder and acromioclavicular joints. The functioning of the PP occurs with the help of the upper limbs. The motor process is facilitated by muscle connections that stretch along the entire spine. The frontal plane is characterized by raising the arms above the horizontal level and lowering them, which is also facilitated by gravity. The level of the shoulder girdle is characterized by forward and backward movement of the arms and scapular rotation.

Injuries and illnesses

The likelihood of damage to the scapula increases when falling on the back, shoulder, arm, or after a direct blow. With closed injuries, there are no wounds; with open injuries, the integrity of the skin is compromised.

Injuries to the bones of the shoulder girdle are common.

Reference. Most often, the scapula is injured in the area of the articular socket and acromion. The most serious injury is considered to be a neck fracture, which can lead to dangerous complications.

Scapula injuries:

The fracture is accompanied by a triangular swelling and pain, which intensifies when the victim tries to move his arm. When a fracture is displaced, a characteristic crunch is heard. In case of an injury in the area of the bone connection, the shoulder and arm are raised; in case of a fracture in the neck area, the arm hangs down. If the acromion process is damaged, the shoulder protrudes forward, and if the coracoid process is damaged, it deepens.
Dislocation of the scapula is a rare occurrence. The injury occurs after a sudden movement of the upper limb to the side. It manifests itself as protrusion of the scapula and intense pain.
Bursitis (inflammation of the joint capsule) can be caused by infection, trauma, or autoimmune diseases. The pathology is accompanied by pain in the affected area, swelling, redness of the skin, numbness, and limited movement in the joint.
Pterygoid scapulae, as a rule, are of congenital origin. Acquired pathology occurs due to prolonged curvature of the spine (scoliosis, kyphosis, etc.).

Common clavicular bone injuries:

Injury. After mechanical impact, small vessels are damaged and a hematoma appears. With a severe injury, the hand becomes numb and mobility is limited.
Dislocations. Damage to the outer edge is diagnosed more often than to the inner edge. The injury occurs when a person falls on an outstretched arm or shoulder. The dislocation is accompanied by pain, one of its ends protrudes from under the skin, and mobility is limited.
A fracture is the most dangerous injury. In case of injury, the victim cannot raise the arm on the injured side, feels sharp pain, and swelling appears.

Non-mechanical pathologies include neuroma, osteochondroma, chondroma. With all of the above diseases, a benign growth appears on the bone, which provokes pain and decreased mobility.

Reference. Chondroma can develop into a malignant formation. Therefore, it is important to identify it in time and then carry out treatment.

Osteomyelitis of the clavicular bone is an infectious disease that manifests itself as pain, redness, and inflammation of the lymph nodes. Occurs due to injury, kidney disease, diabetes, etc.

Ewing's sarcoma is a malignant tumor. The pathology is accompanied by pain, swelling, sleep disorders, shortness of breath, loss of appetite, etc.

The most common injuries to the humerus include dislocations. This is due to the high mobility of the hand. The articular surfaces can shift anteriorly, posteriorly, downwards. When damaged, pain appears, swelling is observed in the affected area, and mobility is limited. If a nerve is pinched, the hand goes numb.

Common causes of a bone fracture: a blow, falling backwards on your elbows, or landing on your hands from a height.

Reference. Most often, a fracture of the humerus occurs in the area of the anatomical or surgical neck, condyles, head, and middle of the bone. The victim feels sharp pain, cannot move the injured limb, and after a while swelling and bruising appear. In addition, the bone in the damaged area is deformed.

Common non-mechanical pathologies of the humerus include osteomyelitis. The infection enters the bone marrow through the blood. Pathology is common, since the humerus is classified as tubular and has an abundant blood supply. If left untreated, bone tissue is destroyed, then fractures occur even as a result of minor external influences.

In addition, arthritis (degenerative-dystrophic changes) of the bony joint of the shoulder is common.

X-ray, MRI, and CT will help identify injuries or diseases of the bones of the upper limb girdle. To assess the general condition of the patient, laboratory tests of blood and urine are performed.

Dislocations are adjusted by a qualified health care professional. Treatment of fractures should be comprehensive: plaster casts, medications, exercise therapy, massage. In severe cases (displaced fractures), surgery is needed to compare bone fragments.

Infectious and inflammatory diseases are treated conservatively or surgically. It all depends on the severity of the pathology, the age of the patient, and his general health.

Diagnosis and treatment

First aid for injuries is to immobilize the injured limb in the position it assumed after the injury. You should absolutely not try to reset a dislocated joint or bone on your own to give it the correct position. After immobilizing (immobilizing) the affected arm, the victim should be given an anesthetic and/or antipyretic and immediately call an ambulance.

Treatment of such injuries is usually carried out at home after applying the basic techniques covered in the Standards of Medical Care in the field of Traumatology and Orthopedics (GEOTAR-Media, 2021, Moscow). After reduction of the dislocation, a tight bandage or plaster splint is applied. Surgery and hospitalization are necessary only in the case of a multiple comminuted fracture of the humerus or a fracture of the scapula of any complexity. Full recovery after a dislocation occurs in about 2 months; after a fracture of the scapula, this process can take up to six months. The treatment prescribed by the doctor and a complex of physical therapy exercises are of great importance.

If other pathologies are diagnosed, depending on the severity, conservative therapy (medicines, physical therapy) or surgery may be performed. Both methods are often prescribed. When the PP is affected by a tumor, therapy is carried out according to the techniques specified in the List of Federal Standards of Medical Care in the Oncology profile.

Biology test on the topic “Musculoskeletal system” (8th grade)