Anatomy of the humerus. Structure and injuries of the humerus

Humerus - people have different meanings for this concept. If we consider anatomy, the shoulder refers to the upper part of the free upper limb, that is, the arm. If we consider the anatomical nomenclature, this section starts from the shoulder joint and ends at the bend of the elbow. According to anatomy, the shoulder is the shoulder girdle. It connects the free upper part to the body. It has a special structure, thanks to which the number and range of movements of the upper limb increases.

Bone anatomy

There are two main bones of the shoulder girdle:

1. Spatula. As you know, this is a flat bone that has a triangular shape. It is located at the back of the body. It has three edges: lateral, medial and superior. Between them there are three angles: upper, lower and lateral. The last of them has a large thickness and a glenoid cavity necessary for the articulation of the scapula and the head of the humerus bone. Adjacent to the depression is a narrowed place - the neck of the scapula. Above the joint cavity there are tubercles - subarticular and supraarticular. The lower corner is easy to feel under the skin; it is located almost at the level of the upper edge of the rib, the eighth in a row. The upper one is located upward and inward.

The costal scapular surface faces the chest. The surface is slightly concave. With its help, the subscapular fossa is formed. The dorsal surface is convex. It has a spine that divides the dorsal scapular surface into two muscles. The spine can be easily felt under the skin. Outwardly, it transitions into the acromion, located above the shoulder joint. It is with the help of its outer extreme point that you can determine the width of the shoulders. There is also a coracoid process, which is necessary for the attachment of ligaments and muscles.

1. Collarbone. It is a tubular bone curved in an S-shape. It connects to the sternum at the medial end, and to the scapula at the lateral end. The collarbone is located under the skin and is easy to feel. It is attached to the chest cage with the help of ligaments and muscles. The connection to the shoulder blade is made using ligaments. Therefore, the lower surface of the clavicle has roughness - lines and tubercles.

The shoulder itself consists of one humerus bone. This is a typical tubular bone. Its body in the upper part has a rounded shape. The lower section has a triangular shape. At the proximal epiphysis of the bone there is the head of the humerus. Its shape is a hemisphere. She, being in this proximal section, is turned towards the scapula. The articular surface rests on it, and the anatomical neck of the humerus bone adjoins it. Outside the neck there are two tubercles that are needed for muscle attachment.

With regard to the greater tubercle of the humerus, we can say that it faces outward. The other tubercle, the small one, faces anteriorly. A crest extends from the greater tubercle of the humerus and the lesser. There is a furrow between them and the ridges. The tendon of the head of the biceps brachii muscle passes through it. There is also a surgical neck, that is, the narrowest part of the shoulder bone, which is located below the tubercles.

The humerus has a deltoid tuberosity. The deltoid muscle is attached to it. During sports training, an increase in this tuberosity and the thickness of the compact bone layer is observed. The groove of the radial nerve runs along the posterior bone surface. The condyle is formed by the distal epiphysis of the humerus.

It has the articular surface necessary to connect to the bones of the forearm. The surface of the joint on the medial side that connects to the ulna is called the trochlea of ​​the humerus. Above it there are pits in front and behind. When flexion and extension of the forearm occur, they include the processes of the elbow bone. The lateral surface is called the head of the condyle of the humerus.

It has a spherical shape and is connected to the radius. The distal end has two epicondyles on both sides, lateral and medial. They are easy to feel under the skin. Their role is to attach ligaments and muscles.

Anatomy of the ligamentous apparatus of the shoulder

It is important to consider the anatomy of not only the bones and their location, but also the ligamentous apparatus.

Damage

The humerus is susceptible to many injuries. One of them is. They are more common in men.

The humerus can break, but in different places:

Fractures of the anatomical neck of the bone, head

They occur as a result of a fall on the elbow or due to a direct blow. If the neck is damaged, wedging of the distal part into the head is observed. The head can be deformed, crushed, and also come off, but in this case it will be turned by the cartilaginous surface towards a fragment of a distal nature.

Signs include bleeding and swelling. The person cannot make active movements and feels pain. If you perform passive rotational movements, the greater tubercle will move together with the shoulder. If the fracture is impacted, the signs are not so pronounced. The victim can make active movements. The diagnosis is confirmed using x-rays.

For impacted fractures of the neck and head, treatment is outpatient. The hand is immobilized. A person takes analgesics and sedatives internally. Physiotherapy is also prescribed. After a month, the splint is replaced with a scarf-type bandage. Working capacity is restored after two and a half months.

Surgical neck fracture

Non-displaced injuries are usually impacted or pinched. If displacement has occurred, the pearl can be adductive or abductive. Adduction fractures occur in the event of a fall with emphasis on the adducted outstretched arm. Abduction fractures occur in the same situation, only the arm is abducted.

If there is no displacement, then local pain is observed, which intensifies with axial load. The humerus may retain its function, but it will be limited. If displacement occurs, the main symptoms are severe pain, pathological mobility, disruption of the shoulder axis, shortening, and dysfunction. First aid consists of administering analgesics, immobilization and hospitalization.

The greater tuberosity suffers mainly from shoulder dislocation. It is torn off and displaced due to reflex contraction of the minor, infraspinatus and supraspinatus muscles. If an isolated fracture occurs, then most likely as a result of a bruise of the shoulder; in this case, displacement is not observed.

Symptoms of such injuries are pain, swelling, and crepitus.

Even passive movements bring severe pain. If the injury is not combined with displacement, immobilization is performed with a Deso bandage. You can also use a scarf. The immobilization period is two or three weeks.

If the fracture is avulsion and combined with displacement, reduction and immobilization is done with a splint or plaster bandage. If there is large swelling and, shoulder traction is used for two weeks. After the patient begins to freely raise the shoulder, abduction of the arm with the splint is stopped. Rehabilitation lasts from two to four weeks.

Fracture of the diaphysis of the bone

It occurs as a result of a blow to the shoulder, as well as a fall on the elbow. Symptoms: dysfunction, shoulder deformity, shortening. Hemorrhage, pain, crepitus and pathological mobility are also observed. First aid is the administration of analgesics and immobilization with a transport splint. Fractures of the diaphysis in the lower and middle third are treated with skeletal traction. Upper third injuries are treated with an abduction splint and shoulder abduction. Immobilization lasts from two to three months.

Fractures in the distal region

Extra-articular fractures can be either extension or flexion, depending on the position of the fall. Intra-articular fractures are transcondylar injuries, V- and T-shaped injuries, as well as fractures of the head of the condyle. Symptoms include pain, crepitus, abnormal mobility, and flexed forearm. First aid consists of transport immobilization with a splint; you can use a scarf. Analgesics are also administered.

The bones of the shoulder girdle play an important role in movement. They need to be protected, because any damage takes a long time to heal.

ENCYCLOPEDIA OF MEDICINE /SECTION^

ANATOMICAL ATLAS

The structure of the humerus

The humerus is a typical long tubular bone that forms the proximal (upper) part of the arm. It has a long body and two ends, one of which articulates with the scapula at the shoulder joint, the other with the ulna and radius bones at the elbow joint.

The apex of the humerus - its proximal end - has a large, smooth, hemispherical articular surface that articulates with the glenoid cavity of the scapula to form the shoulder joint. The head is separated from the rest by a narrow interception - an anatomical neck, below which there are two bony protrusions - the greater and lesser tubercles. These tubercles serve as sites of muscle attachment and are separated by the intertubercular groove.

BODY OF HUMERUS

_(DIAPHYSUS)_

There is a slight narrowing at the top of the body of the humerus - the surgical neck is a common site for fractures. The relatively smooth surface of the diaphysis has two distinctive features. Approximately in the middle of the length of the body of the humerus, closer to its upper epiphysis on the lateral (side) surface, there is a deltoid tuberosity, to which the deltoid muscle is attached. Below the tuberosity, a spiral groove of the radial nerve runs along the posterior surface of the humerus. In the deepening of this groove pass the radial nerve and deep arteries of the shoulder.

The lateral edges of the diaphysis in its lower part pass into protruding medial (internal) and lateral epicondyles. The articular surface is formed by two anatomical formations: the block of the humerus, which articulates with the ulna, and the head of the condyle of the humerus, which articulates with the radius.

Humerus, posterior view

humerus

Articulates with the glenoid cavity of the scapula at the shoulder joint.

Anatomical -

It is a remnant of the growth plate where bone growth occurs in length during childhood.

Body of humerus

The diaphysis makes up the bulk of the length of the bone.

Radial nerve groove

It runs obliquely along the posterior surface of the middle part of the body of the humerus.

Humerus block

Medial epicondyle -

More prominent bony projection than the lateral epicondyle.

Greater tuberosity

Place of muscle attachment.

Humerus, front view

Lesser tubercle

Place of muscle attachment.

Surgical neck

Narrow interception, frequent site of fractures.

Deltoid tuberosity

Insertion site of the deltoid muscle.

Head -

humeral condyle

It has a spherical shape, articulates with the head of the radius.

Lateral epicondyle

External bony prominence.

Anatomical neck

Intertubercular groove

It contains the tendon of the biceps brachii muscle.

At these points the bone can be easily felt under the skin.

Humerus fractures

Most fractures of the upper humerus occur at the level of the surgical neck as a result of a fall on an outstretched arm. Fractures of the body of the humerus are dangerous due to possible injury to the radial nerve, which lies in the groove of the same name on the posterior surface of the bone. Damage to it can cause paralysis of the muscles of the back of the forearm, which is manifested by drooping of the hand. H This x-ray shows a fracture of the upper body of the humerus. This injury usually occurs when falling on an outstretched arm.

In children, humerus fractures are often localized in the supracondylar region (in the lower part of the humerus body above the elbow joint). Typically, the mechanism of such an injury is a fall on the arm, slightly bent at the elbow. This can damage nearby arteries and nerves.

Sometimes, with complex fractures of the humerus, it becomes necessary to stabilize it with a metal pin, which holds the bone fragments in the correct position.

Medial epicondyle

A bony prominence that can be felt on the inside of the elbow.

Humerus block

Articulates with the ulna.

The skeleton of the free upper limb (skeleton membri superioris liberi) consists of the humerus, two bones of the forearm and bones of the hand.

Brachial bone

Humerus, humerus, is a long lever of movement and develops like a typical long tubular bone. According to this function and development, it consists of a diaphysis, metaphyses, epiphyses and apophyses.

The upper end is equipped with a spherical articular head, caput humeri(proximal epiphysis), 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, collum anatomicum.

Immediately behind the anatomical neck there are two muscular tubercles (apophyses), of which larger, tuberculum majus, lies laterally, and the other, smaller, tuberculum minus, a little in front of him. From the tubercles downwards there are bone ridges (for muscle attachment): from the greater tubercle - crista tuberculi majoris, and from small - crista tuberculi minoris.

Between both tubercles and ridges there passes groove, sulcus intertubercularis, which houses the tendon of the long head of the biceps muscle.

The part of the humerus lying immediately below both tubercles at the border with the diaphysis is called surgical neck - collum chirurgicum(the site of the most common shoulder fractures). The body of the humerus in its upper part has a cylindrical outline, while at the bottom it is clearly triangular. Almost in the middle of the bone body, on its lateral surface there is a tuberosity to which it is attached deltoid muscle, tuberositas deltoidea.

Behind it, along the posterior surface of the bone body from the medial side to the lateral side, a flat plane runs in the form of a gentle spiral groove of the radial nerve, sulcus nervi radialis, seu sulcus spiralis.

Widened and slightly anteriorly curved lower end of the humerus, condylus humeri, ends on the sides with rough protrusions - medial and lateral epicondyles and, epicondylus medialis et lateralis, lying on the continuation of the medial and lateral edges of the bone and serving for the attachment of muscles and ligaments (apophyses). The medial epicondyle is more pronounced than the lateral one, and on its posterior side it has groove of the ulnar nerve, sulcus n. ulnaris.

An articular surface is placed between the epicondyles for articulation with the bones of the forearm (disgal epiphysis). It is divided into two parts: medially lies the so-called block, trochlea, having the form of a transversely located roller with a notch in the middle; it serves for articulation with the ulna bone and is covered by it tenderloin, incisura trochlearis; above the block, both in front and behind, is located along the fossa: in front coronoid fossa, fossa coronoidea, back hole olecranon, fossa olecrani.

These pits are so deep that the bony partition separating them is often thinned to the point of being translucent, and sometimes even perforated. Lateral to the block, the articular surface is placed in the form of a segment of a ball, the head of the condyle humerus, capitulum humeri, serving for articulation with the radius. Front over capitulum there is a small radial fossa, fossa radialis.

Ossification. At the time of birth, the proximal epiphysis of the shoulder still consists of cartilaginous tissue, so the head of the humerus is almost not visible on an x-ray of the shoulder joint of a newborn.

Subsequently, the sequential appearance of three points is observed: 1) in the medial part of the head of the humerus (0 - 1 year) (this bone core can also be present in a newborn); 2) in the greater tubercle and lateral part of the head (2 - 3 years); 3) in tuberculum minus (3 - 4 years). These nuclei merge into a single head of the humerus (caput humeri) at the age of 4-6 years, and synostosis of the entire proximal epiphysis with the diaphysis occurs only at the 20-23rd year of life.

Therefore, on radiographs of the shoulder joint belonging to children and young people, according to the indicated ages, clearings are noted at the site of the cartilage separating the parts of the proximal end of the humerus that have not yet fused from each other. These lucencies, which are normal signs of age-related changes, should not be confused with cracks or fractures of the humerus. For ossification of the distal end of the humerus, see the description of ossification of the bones of the forearm.

Video of normal anatomy of the humerus

The shoulder refers to the long tubular bones of humans. The anatomy is simple and is determined by a number of functions performed. On its surface there are anatomical formations, such as the head, medial condyle, as well as tubercles and pits, which serve as attachment points for muscles and ligaments. The humerus functions as a lever. Fractures are very dangerous, because due to damage to the bone marrow canal, a fat embolism can develop or a vessel may become blocked.

Most often, the shoulder suffers as a result of fractures in the area of ​​the anatomical neck.

Structure and anatomy

At the top of the bone there is a round formation - the head, which is an integral part of the joint. It is separated from the rest of the bone by a narrow groove. It is called the anatomical neck. It is in this part that fractures most often occur. Behind it is the place of attachment of the main muscles of the shoulder, represented by two tubercles - large and small, as well as ridges. The lesser tubercle is located in front of the shoulder. There is a tuberosity in the middle of the bone. This is where the deltoid muscle attaches. On the side of the elbow, the humerus ends with 2 epicondyles, between which there is an articular surface. The medial condyle is much larger than the lateral one. There are also 2 recesses located here - the olecranon process or ulnar fossa and the radial one.

Functions of the humerus

The shoulder structure is actually a lever and increases the range of motion of the upper limb. In addition, the bone is involved in maintaining balance when the center of gravity shifts while walking. This element determines the correct support of a person on his hands when climbing stairs and in other specific body positions.

Damage: causes and symptoms

When the shoulder joint is dislocated, a person feels sharp pain.

Dislocation of the shoulder and elbow joint is common and is associated with high mobility of the upper limb. There are anterior, posterior and inferior displacement. If damaged, it becomes difficult to move the limb, pain is felt, and swelling is visualized. When a nerve is pinched, the skin becomes numb. Dislocations are distinguished as new and old. At the same time, a protrusion of the greater tubercle or a fracture of the neck may occur. The shoulder is swollen, painful, there is noticeable hemorrhage, sensitivity in the arm and fingers is lost.

A fracture of the humerus occurs due to significant force. This happens when you fall backward on your elbows or forward on your outstretched arms. Bone fracture occurs in anatomically weak areas. These include:

• anatomical and surgical neck;
• condyle area;
• area of ​​the head of the humerus;
• the middle of the bone.

Immediately after the injury, the patient feels a sharp pain in the arm, as well as the inability to perform actions with it. The exact amount of movement lost depends on the immediate location of the injury. After some time, severe swelling of the shoulder is observed, and bruising and bruising may develop. In this case, the limb is significantly deformed.

Diseases

Among the diseases of this joint, arthritis is common.

A common disease is the introduction of infection into the bone marrow through the blood. Damage to the shoulder occurs because this bone is tubular and has an abundant blood supply. As a result of the development of this disease, bone tissue can decompose, and then pathological fractures form (without the participation of strong external influences). In addition, arthritis of the shoulder and elbow joints may develop.

The special anatomy of the shoulder joint ensures high mobility of the arm in all planes, including 360-degree circular movements. But the price for this was the vulnerability and instability of the joint. Knowledge of the anatomy and structural features will help to understand the cause of diseases that affect the shoulder joint.

But before proceeding to a detailed review of all the elements that make up the formation, it is necessary to differentiate two concepts: the shoulder and the shoulder joint, which many confuse.

The shoulder is the upper part of the arm from the armpit to the elbow, and the shoulder joint is the structure that connects the arm to the torso.

Structural features

If we consider it as a complex conglomerate, the shoulder joint is formed by bones, cartilage, joint capsule, bursae, muscles and ligaments. In its structure, it is a simple, complex spherical joint consisting of 2 bones. The components that form it have different structures and functions, but are in strict interaction designed to protect the joint from injury and ensure its mobility.

Shoulder joint components:

• spatula
• brachial bone
• labrum
• joint capsule
• bursae
• muscles, including the rotator cuff
• ligaments

The shoulder joint is formed by the scapula and humerus, enclosed in a joint capsule.

The rounded head of the humerus is in contact with the fairly flat articular bed of the scapula. In this case, the scapula remains practically motionless and the movement of the hand occurs due to the displacement of the head relative to the articular bed. Moreover, the diameter of the head is 3 times larger than the diameter of the bed.

This discrepancy between shape and size provides a wide range of movements, and the stability of the articulation is achieved through the muscular corset and ligamentous apparatus. The strength of the articulation is also given by the articular lip located in the scapular cavity - cartilage, the curved edges of which extend beyond the bed and cover the head of the humerus, and the elastic rotator cuff surrounding it.

Ligamentous apparatus

The shoulder joint is surrounded by a dense joint capsule (capsule). The fibrous membrane of the capsule has varying thicknesses and is attached to the scapula and humerus, forming a spacious sac. It is loosely stretched, which allows you to move and rotate your hand freely.

The inside of the bursa is lined with a synovial membrane, the secretion of which is synovial fluid, which nourishes the articular cartilages and ensures the absence of friction when they slide. On the outside, the joint capsule is strengthened by ligaments and muscles.

The ligamentous apparatus performs a fixing function, preventing displacement of the head of the humerus. Ligaments are formed by strong, poorly tensile tissues and are attached to bones. Poor elasticity causes damage and rupture. Another factor in the development of pathologies is an insufficient level of blood supply, which is the cause of the development of degenerative processes of the ligamentous apparatus.

Shoulder joint ligaments:

1. coracobrachial
2. top
3. average
4. lower

Human anatomy is a complex, interconnected and fully thought-out mechanism. Since the shoulder joint is surrounded by a complex ligamentous apparatus, for the sliding of the latter, mucous synovial bursae (bursae) are provided in the surrounding tissues, communicating with the joint cavity. They contain synovial fluid, ensure smooth operation of the joint and protect the capsule from stretching. Their number, shape and size are individual for each person.

Muscular framework

The muscles of the shoulder joint are represented by both large structures and small ones, due to which the rotator cuff is formed. Together they form a strong and elastic frame around the joint.

Muscles surrounding the shoulder joint:

• Deltoid. It is located on top and outside the joint, and is attached to three bones: the humerus, scapula and clavicle. Although the muscle is not directly connected to the joint capsule, it reliably protects its structures on 3 sides.
• Biceps (biceps). It is attached to the scapula and humerus and covers the joint from the front.
• Triceps (triceps) and coracoid. Protects the joint from the inside.

The rotator cuff allows a wide range of motion and stabilizes the head of the humerus by holding it in the socket.

It is formed by 4 muscles:

1. subscapularis
2. infraspinatus
3. supraspinatus
4. small round

The rotator cuff is located between the head of the humerus and the acromin, the process of the scapula. If the space between them narrows due to various reasons, the cuff is pinched, leading to a collision of the head and acromion, and is accompanied by severe pain.

Doctors called this condition “impingement syndrome.” With impingement syndrome, injury to the rotator cuff occurs, leading to its damage and rupture.

Blood supply

The blood supply to the structure is carried out using an extensive network of arteries, through which nutrients and oxygen enter the joint tissues. Veins are responsible for removing waste products. In addition to the main blood flow, there are two auxiliary vascular circles: the scapular and the acromiodeltoid. The risk of rupture of large arteries passing near the joint significantly increases the risk of injury.

Elements of blood supply

• suprascapular
• front
• back
• thoracoacromial
• subscapularis

• humeral
• axillary

Innervation

Any damage or pathological processes in the human body are accompanied by pain. Pain can signal the presence of problems or perform security functions.

In the case of joints, soreness forcibly “deactivates” the diseased joint, preventing its mobility to allow injured or inflamed structures to recover.

Shoulder nerves:

• axillary
• suprascapular
• chest
• ray
• subscapular
• axle

Development

When a child is born, the shoulder joint is not fully formed, its bones are separated. After the birth of a child, the formation and development of shoulder structures continues, which takes about three years. During the first year of life, the cartilaginous plate grows, the articular cavity is formed, the capsule contracts and thickens, and the ligaments surrounding it strengthen and grow. As a result, the joint is strengthened and fixed, reducing the risk of injury.

Over the next two years, the articulation segments increase in size and take on their final shape. The humerus is the least susceptible to metamorphosis, since even before birth the head has a rounded shape and is almost completely formed.

Shoulder instability

The bones of the shoulder joint form a movable joint, the stability of which is provided by muscles and ligaments.

This structure allows for a large range of movements, but at the same time makes the joint prone to dislocations, sprains and ligament tears.

Also, people often encounter a diagnosis such as instability of the articulation, which is made when, when moving the arm, the head of the humerus extends beyond the articular bed. In these cases, we are not talking about an injury, the consequence of which is a dislocation, but about the functional inability of the head to remain in the desired position.

There are several types of dislocations depending on the displacement of the head:

1. front
2. rear
3. lower

The structure of the human shoulder joint is such that it is covered from behind by the scapula, and from the side and above by the deltoid muscle. The frontal and internal parts remain insufficiently protected, which causes the predominance of anterior dislocation.

Functions of the shoulder joint

High mobility of the joint allows for all movements available in 3 planes. Human hands can reach any point of the body, carry heavy loads and perform delicate work that requires high precision.

Movement options:

• lead
• casting
• rotation
• circular
• bending
• extension

It is possible to perform all of the listed movements in full only with the simultaneous and coordinated work of all elements of the shoulder girdle, especially the collarbone and acromioclavicular joint. With the participation of one shoulder joint, the arms can only be raised to shoulder level.

Knowledge of the anatomy, structural features and functioning of the shoulder joint will help to understand the mechanism of injury, inflammatory processes and degenerative pathologies. The health of all joints in the human body directly depends on lifestyle.

Excess weight and lack of physical activity harm them and are risk factors for the development of degenerative processes. A careful and attentive attitude towards your body will allow all its constituent elements to work for a long time and flawlessly.