Skeleton of the upper limb. Functions of the skeleton of the upper limbs

In the course of evolution, the skeleton of the limbs of man underwent significant changes. So, legs, performing the tasks of movement and support, ensure the preservation of the body in a vertical position, and the hands became tools of labor. Next, let us consider in more detail the skeleton of the upper limb: the structure and the tasks that it performs.

General information

The skeleton of the upper limbs of man acquired considerable mobility during phylogenesis. Due to the presence of the clavicle, which ensures the connection of the bones of the hands and trunk, people can perform quite extensive movements. In addition, the elements that enter the skeleton of the free upper limb have a movable articulation with each other. This is especially true for the area of the hand and forearm. The functions of the skeleton of the upper limbs are quite extensive. Hands are adapted to difficult kinds of labor activity. Due to the presence of a large number of bones and articulations, the fingers can perform different work: from writing to assembling any mechanisms. The leg, acting as an organ of movement and support of the trunk in space, includes more massive and thick bones. Their mobility relative to each other is less significant. The skeleton of the upper and lower limbs is made up according to the general plan. It includes two parts.

Departments of the skeleton of the upper limb: the bone of the belt

This part includes:

• Shoulder. It is represented as a triangular flat bone. There are three edges in the blade. In particular, there is a lateral, medial and upper part. Also in the scapula are three angles. One - the lower, the second - the medial, and the third - the lateral, respectively. The scapula is adjacent to the back of the chest. It is located in the zone between the II-VII ribs. In the segment there is an articular cavity. It serves to connect with the clavicle. A projection is seen from the back surface of the scapula. It is located transversely. This protrusion is the tip of the scapula, which separates the subacute and suppurative fossa.
• Clavicle. It is represented as an S-shaped tubular bone. It distinguishes two ends - the shoulder (acromial) and the sternum, and the body. Clavicle is the only element through which the skeleton of the upper limbs of a person connects to the bone structure of the trunk. The sternum end of the segment is thickened. It joins with the handle of the sternum. The flat shoulder end is connected to the shoulder blade.

The second part

In it, the skeleton of the upper limb consists of a hand, a forearm and a shoulder element. The last segment is represented by one bone - humerus. The brush includes finger phalanges, a pastern and a wrist. Two elements are distinguished in the forearm. It is represented by the elbow and radius bones.

Brachial bone

It is presented in the form of a tubular long element. In the bone, diaphysis (body) and 2 epiphyses (ends) are distinguished: upper and lower. The first is a round articular head. It serves to connect with the scapula. The upper end is separated from the body by an anatomical neck. Below it, on the outside, there are hillocks (elevations) - small and large. They are separated by a furrow. The narrowed part in the body, which is closer to the head, is called the "surgical neck". On the surface of the bone there is also tuberosity. It acts as a site for joining the deltoid muscle. The lower epiphysis has an extension and passes into the condyle. It serves to connect in the joint with the radial and ulna bones.

Forearm

In this part, the skeleton of the upper limb includes two elements:

• The ulna. It lies on the inner surface of the little finger (V finger). The upper end of the element is more massive. It distinguishes two processes: behind the elbow and in front - coronary. They are separated by a block-shaped notch for connection with the bone of the shoulder. The outer (lateral) side of the coronoid process contains a radial incision. It forms a joint with a circle. At the lower end, the ulna forms the head. It distinguishes the articular surface in the form of a circle for connection with the ulnar notch in the radial element. On the inner (medial) side is a styloid process.
• Radial bone. It is presented in the form of a long tubular element. Passes the radial bone along the outer surface from the side of the large (first) finger. Its upper end is formed by a cylinder head. It has an articular fossa and a circle. The upper ends in the radial and ulnar bones are involved in the formation of the joint. The lower part has an ulnar incision, a subulate lateral process. There is also a carpal articular surface. The lower sides of the radial and ulnar bones form a wrist joint with the upper row of wrist bones.

Brush

The skeleton of the upper limb in this zone is represented by the bones of the wrist, pastern and fingers. The first zone consists of two rows of spongy short bones (four in each). In the wrist of the bone articulate. The upper side of the first row has connections with the radius, through the articular surface. The lower part of the second joins the base of the metacarpal elements. The pastern is represented by five tubular short bones. To begin to count from the big finger. Each metacarpal bone has a head, a base and a body. The first element is articulated with the upper phalanx in the corresponding finger. Phalanges are tubular short bone elements. They have a head, a base and a body. In the first two elements, articular surfaces are distinguished. In the upper phalanges this segment has a joint with a head in the corresponding bone of the pastern, in the lower and middle - with the phalanx located above (proximally). In the big finger there are two tubular bones, in the other - three.

Age features of development: the bone of the belt

All elements included in the skeleton of the upper limb, except the clavicle, pass the connective tissue stage, cartilaginous, bone.

• Shoulder. Its primary site of ossification is laid on the second month of intrauterine development. From this point, the awn and the body of the segment develop. By the end of the first year of life in the beak-shaped process an independent ossification site is laid, and by 15-18 years it is formed in the acromion. In 15-19, the coracoid process is fused with the scapula.
• Collarbone. Its ossification occurs early enough. This section of the skeleton passes one - connective tissue - stage. At the 6th to 7th week. Inside the womb appears the point of ossification. It is located in the center of the connective tissue rudiment. From this site the formation of the acromial end and the body of the clavicle occurs, which in newborns almost entirely consists of bone tissue. In the sternal part, cartilage is formed. The core of ossification appears in it only to 16-18 years, which fuses with the bone in 20-25 years.
• Shoulder. In the proximal epiphysis, secondary ossification points are formed: in the large and small tubercles to the 1-5th, and in the head, usually at 1 year of age. At the age of 3-7 liters. There is their fusion, and 13-25 years - joining the diaphysis. In the distal epiphysis, the ossification site is formed up to 5 years of life, the lateral epicondyle - up to 4-6, the medial - up to 4-11. By 13-21 year all the parts are fused with the diaphysis.

middle part

• Elbow bone. At 7-14 years in the proximal epiphysis the ossification point is laid. It starts the elbow process, in which there is a block-shaped notch. By 3-14 years ossification sites are formed in the distal epiphysis. Growing up, bone tissue forms an awl-shaped process and a head. The fusion with the body of the proximal epiphysis takes place in the 13-20th year, the distal epiphysis takes place on the 15-25th.
• Radius. By 2.5-10 years the site of ossification in the proximal epiphysis is laid. The fascination with diaphysis occurs to 13-25 years.

Development of brush elements

• Wrist. After birth ossification begins. By the first and second years of life, the point of ossification forms in the hook-shaped and celiac bones, on the third - in the trihedral, 4 - in the semilunar, 5 - in the navicular, 6-7 in the trapezoid, on the 8th - In the pea.
• Pastern. The laying of bones forming this part occurs earlier than in the wrist. The zones of ossification in the diaphysis are laid by the 9-10th week of embryonic development, with the exception of the first bone. In it, the site is formed by 10-11 weeks. In the epiphyses, the ossification zones appear between 10 months. And 7 years. By 15-25 years there is a fusion of the diaphysis and the head of the metacarpal bone.
• Phalanges. The points of ossification of the bodies of the distal elements appear by the middle of the second month of embryonic development, the proximal ones to the beginning, and the middle ones to the end of the third month. In phalangeal areas, sites appear between 5 months. And 7 years. The increment to the body occurs in 14-21 years.

The skeleton of the upper limbs has a complex structure in which each element plays its role.