Clavicle: where is the anatomy, function, structure

The main privilege of a person is strangeness. It became possible due to cardinal changes in the system of support and movement, which includes the skeleton and muscles. All its departments have the best functional adaptability to the vertical position of the body. This led to the release of the upper limb from participation in the movement of the body and its inclusion in various types of physical activity: retention and precise manipulation of objects and instruments of labor, the performance of purely human actions. Examples illustrating them are the ability to write, play musical instruments, draw, sew, knit, and so on.

In this article, we will focus on the features of the structure of the upper extremity belt, which includes the scapula and collarbone. Where is it located, what functions does it perform, what is its role in the human musculoskeletal system?

Place of the clavicle in the human skeleton

The bone that enters the belt of the upper limbs is connected to the breastbone by means of the sternoclavicular joint. The lateral part of the clavicle is connected with the shoulder blade - an acromion. At this point, the bone has a knobby, rough surface for a strong attachment of the muscular apparatus of the shoulder with the help of a system of ligaments. To better understand what a clavicle is, consider the structure of one of the departments of the musculoskeletal system - the upper extremity belts.

Clavicle as a component of the upper extremity belt

To the bones of the hand were connected to other parts of the trunk, in the human skeleton there is a special department consisting of paired bones - triangular scapula and clavicles. In the structure of the body, the humeral girdle, including the collarbone, already has vertebrates, beginning with representatives of the Nadklassa Pisces. It is sufficiently developed in mammals using their forelimbs in the process of capturing prey or movement by the method of brachyce (for example, in gibbons). Let's consider further where the collarbone is located and what is this part of the body. It has the form of the Latin letter S, connected by its inner part with the sternum, and external - with a scapula, for strength these joints are strengthened with ligaments.

At the time of vertical movement of the shoulder, the bone rotates around its axis like a key in a keyhole, hence the name - the collarbone. Further we will stop on its functions in an organism.

The role of the bones of the upper extremity belt in the support and movement system

Previously, we identified a place in the skeleton of the person where the collarbone is located. Anatomically, it is connected to the scapula and sternum, providing a support on which the humerus is attached. The structure of such a link-lever is the best way to increase the amplitude of the movements of the hand. Clavicle also serves as a transfer link for mechanical action from the upper limb to the chest and spine. It is attached to several important muscles that play a static and dynamic role. Anatomy of the clavicle, the functions that are inherent in it, are primarily due to the internal structure. We will become acquainted with it in more detail.

Histogenesis of bone tissue

In the embryonic period of development from the middle germinal leaf formed such types of cells as fibroblasts, chondroblasts and osteoblasts. Of these, in the future, such tissues form the organs of the musculoskeletal system, as connective, cartilaginous and bone. To answer the question: what is a clavicle from the point of view of the internal structure, let us recall that in the human skeleton there are bones, which are called mixed. They are formed by elements of different origins. For example, the clavicle is formed partly from the connective tissue that has undergone osteogenesis without the formation of cartilage, partly from the chondrocytes in which the ossification process was carried out.

What muscles are attached to the upper extremity belt

All the movements of the human body are carried out in the coordinated work of the bones of the skeleton and the muscles attached to them by ligaments. So, to set in motion the upper limb in the shoulder joint, the deltoid muscle contracts. Let's remember where the man's collarbone is, and find out its role in the movement of the hand. It is to the upper part and the front edge of this bone, which enters the belt of the upper limbs, that the deltoid muscle is attached. To the posterior edge of the clavicle, trapezius and sternocleidomastoid muscle join the trapezoidal and conical ligaments.

The first of them statically holds the upper back in an upright position, the second provides turns and inclinations of the head and can participate in respiratory movements.

How is clavicle forming in embryogenesis

In order to clearly understand what a clavicle is, consider the mechanism of laying bone tissue. Formation of the skeleton in the embryo begins with a 5-6 week of intrauterine development and represents the process of ossification. And the first bone, which is formed in osteogenesis, is the clavicle. It will be one of the last fully formed, whose ossification lasts up to 21 years of a person's life. Its appearance begins with the union of the cells of the middle germinal layer into groups that are anatomically connected with the capillaries of the embryo.

The division and differentiation of primary mesenchymal cells results in the appearance of fibers consisting of fibroblasts. Then they accumulate in their composition a collagen-like substance - osseomucoid and become a kind of fiber. Around them appear osteoblasts - the primary cells of bone tissue, starting to produce mineral substances. Fibrous strands are impregnated with salts, lose elasticity and become rigid. Mature osteocytes are formed, and the capillaries are surrounded by osseous plates that look like concentric rings and cylinders. The outer layer of fibroblasts is transformed into a periosteum covering the clavicle.

Pathology of the bones of the upper limb

Above we determined what a clavicle is and how it is formed in the process of embryonic development of man. Anomalies of the clavicles arise from the violation of normal osteogenesis in the embryo and are due to the hereditary predisposition of the person.

Thus, hypoplasia, which has symptoms of underdevelopment or complete absence of the clavicle in the upper limb belt, is explained by the defect of the gene located in the autosome and located in the dominant state. Such a violation, as a cranial-clavicular dysostosis, is manifested by anomalies in the development of the facial and brain sections of the skull and is accompanied by pathological mobility of the scapula and clavicles, as well as dislocations in the acromioclavicular joint. Quite often, the pathology of the upper extremity belt is recorded along with other disorders in the structure of the skeleton, for example, in the Golts syndrome, abnormalities in the development of the dental apparatus, excessive synthesis of melanin and trophic skin lesions are combined with clavicular hypoplasia.

In this article, we examined the structure, functions, possible pathologies of the clavicle, which is an integral part of the upper limb belt of the human skeleton.