What includes the upper limb of a person

The musculoskeletal system of the human body is a real miracle of nature. It supports all parts of the body in the right position, protects vital organs and provides striking mobility to the entire body. Belt of the upper limbs is responsible for fixing the arms to the axial skeleton.

Design of clavicles and shoulder blades

The composition of the upper extremity belt implies the construction of two scapulae, two clavicles and the skeleton of the extremity itself. It is the belt of the upper limbs that creates the shape of the human shoulders. Hands connect with the body of the shoulder blades and clavicles, which form the belt of the upper limbs. The blades are located at the top of the back, they are triangular in shape, they are connected with the spine and ribs with the help of the musculature. The scapula is paired with the clavicle, and the collarbone is connected to the sternum and ribs. The clavicle has the form of a curved bone passing between the sternum and the outer angle of the scapula.

The skeleton of the upper extremity belt is constructed from the following parts:

• 2 clavicles;
• 2 blades;
• Humerus bones;
• Radial bones;
• Ulnar bones;
• Wrists;
• Metacarpal bones;
• Phalanx of fingers.

Belt Belt Function

The main function that the belt of the upper limbs of a person performs is to create a strong and maneuverable support for the hands. Unlike the pelvic girdle, it does not rigidly connect to the axial skeleton. The basic bones of the upper extremity belt: the clavicle, which forms the common joint with the sternum, and the shoulder blade connects with the bones of the trunk with powerful muscles. As a result, the shoulders actively participate in the movements of the hands, increasing the amplitude and, accordingly, the efficiency of the work.

Bones of the upper X limbs of a person have a structure, as in the skeleton of vertebrates, and consist of 3 divisions - the shoulder, the forearm and the wrist. Muscles associated with this belt, strengthen the shoulder joint and are responsible for most of the movements of the hands. Shoulder - a wide plate in the form of a triangle, located behind the chest from the back, is part of the belt of the upper limbs. Has a flat hollow of the shoulder joint, into which the head of the humerus is placed. The shoulder joint is relatively unstable, it provides the maximum amplitude of movements, but it is sensitive to dislocations and other injuries.

The main bones of the hands

The humerus is represented as a long tubular bone of the upper extremity belt, two long elbow and radius bones are attached to it. The humerus forms an elbow joint with both bones, and the brush connects only to one of them - the wrist joint. The elbow is located on the inside. All the bones of the hand are linked together by the joints.

The main of them are:

• brachial;
• Wrist band;
• Ulna.

Joints are very diverse in movement, with active mobility, which led to the transformation of the forelimb, that is, the hand, in the course of evolution into the organ of labor. The bones of the elbow and ray are more stable than the humerus, respectively, the movements are less free. The joints of the fingers are even stronger. According to the structure of the skeleton, the arm and leg are very similar. Their main difference is the device of the brush, in which the thumb is separated from the others, which allows the hand to make grabbing movements. Between the wrist and the metacarpal bone of this finger is the only saddle joint in the human body, the movement in which is much freer than at the base of the first toe.

Structure of the elbow joint

The upper limb belt includes an elbow joint, which consists of two parts: block-shaped and globular. The first connects the shoulder of the humerus with the ulnar cavity, it also provides flexion-extensor movements with hands. The globular part connects the head of the humerus with the radial fossa. This allows you to twist the forearm. In general, the joint is quite stable due to the large surface of the joint and strong ligaments. The radius of the bone is the main one in the forearm. It forms a joint with a wrist. The ulna, together with the radial one, forms the elbow joint.

Structure of the shoulder joint

The upper extremity belt includes the shoulder joint. The brachial spherical joint is the most mobile in the human body. Its almost flat hollow on the scapula is articulated with the hemispherical head of the humerus. This device makes it possible to freely rotate the hand in all directions. The bone turns almost in a circle, up and down. In this mobility, there are disadvantages, due to the fact that the strength of the joint is lowered, dislocations often occur in this joint. The second joint is formed by a scapula and clavicle. In it often there is a stretching of ligaments at falling on the extended hand or at a blow from the front on the shoulder.

Wrist

This part of the hand has a rather complex design. The brush consists of 3 departments, which, in turn, have 27 bones. At the base of the palm is 5 metacarpal bones and 8 bones of the wrist. The skeleton of the fingers consists of 14 phalanges, 2 bones in the thumb and 3 in each of the four. The hand has a highly specialized structure. In infants, they are only indicated, gradually forming, they will be clearly visible only to the age of seven, and their ossification terminates much later, approximately to 10-13 years. To the same period, the ossification of the phalanx of the fingers is completed.

Ligaments and muscles of the upper extremity belt

Since the shoulder joint is sufficiently mobile, and the shoulder girdle is not rigidly connected to the axial skeleton, the muscles of the upper extremity belt have a special function. The muscles connect the arm with the trunk and protrude shock absorbers. The deltoid muscle is the largest and strongest in the shoulder, connects the scapula and the humerus. It is thanks to her that the hand rises and moves forward and backward.

The rotator cuff consists of four smaller muscles:

• Subacute;
• Boring;
• Small round;
• Subscapular.

They also control the rotation of the arm and strengthen the shoulder joint.

The main muscles of the upper limb belt

The upper limb has a pair of main muscles: the biceps and triceps, which form a pair of antagonists: if one shrinks, the other one relaxes. Biceps, or biceps arm, goes from the scapula to the radius. If you strongly bend your arm, you can feel it well. The triceps, or triceps arm muscle, connects the scapula to the ulnar bone. It is not so noticeable, but larger than the biceps. Moving, they act as one muscle group. For example, during the lifting of the forearm, the bicep is contracted - the muscle that pulls the forearm to the shoulder. At the same time stretches and triceps, extensor muscle, which allows you to again straighten your arm.

Extensors and flexors

Complex movements of the wrist and hand are provided mainly by coordinated work of the set of muscles passing in the forearm. These are flexors and extensors. Flexors bring their palms to their forearms and squeeze their fingers. They pass on the inside of the hand. Extensors straighten the wrist and fingers, bringing their rear surface closer to the forearm. To unravel the palm and take it an object, requires a well-coordinated work of the 35 muscles of the forearm and hand. In addition, the muscles of the forearm deflect the wrist to the left and right, rotate it, rotate the palm and fix the wrist and fingers in the desired position. Thin movements of the fingers are controlled by the own muscles of the bone, going from the bones of the wrist to the base of the first phalanges. The work of the remaining phalanges is provided by the long tendons of the flexors and extensors that are in the forearm.

Age and prevention of bone aging

The belt of the upper limbs of a person needs anti-aging prophylaxis. With age, the strength of bones decreases and the risk of fractures increases. Age-related bone loss is almost irreversible, but they can and should be prevented or significantly slowed down. Overexertion of the musculature of the shoulders and back is fraught with a very painful condition. People spending whole days at the computer and desk often slouch or are in a hunched pose. Hence the stiffness of constantly tensed muscles and the stretching of the musculature of the shoulders and back, which threatens the appearance of painful muscular nodes and tension headaches.

It is necessary to strengthen the belt of the upper limbs, namely the musculature of the shoulders and back, through exercises that straighten the thorax and unload muscles and ligaments. Very useful are the mixing and dilution of the shoulders, as well as shrugging the shoulders. Physical education relieves pain, strengthens muscles and bones, increases the flexibility of the body, and hence, the mobility and ability to work.