The structure of the human hand
Why do we need hands
The upper limbs of a person by nature are not as strong as the lower ones. But, on the other hand, the structure of the hand allows it to perform a lot of a variety of operations, from playing the piano to carrying heavy loads. It is controlled by nerve impulses coming from the brain, like other organs. Our upper limbs consist of several main parts. Next, we consider each of them and the structure of the human hand as a whole.
Upper limb construction
The hand consists of five fingers and a palm. It consists of twenty-seven small bones. All fingers, except the large, have three phalanges, which, bending, allow you to embrace objects. The forearm is formed by the radial and ulnar bones. Their muscles are divided into two groups, with which you can turn the palm up or down. The largest joint in the upper body of any of us is the shoulder. It is formed by the combination of bone and shoulder blade In this area there are a lot of nerves and ligaments. The shoulder girdle is formed by a pair of shoulder blades and collarbone.
Naturally, the hands are not only bones. Muscles that lead to
The movement of the fingers and hand, mainly located in the forearm. Biceps are connected to it through tendons and ligaments. Its upper part is attached to the shoulder blade. The biceps muscle, which is part of the biceps, is responsible for flexing and raising the arm. Therefore, it is well developed in people accustomed to hard physical labor. The muscle lifter holds the spatula. Three-headed and deltoid are also attached to it. All other muscles related to the shoulder girdle are located in the chest or neck.
Features of the design of the upper limbs
The structure of the arms is such that the possibility of bending them in the elbow gives them greater mobility, functionality. The range of movements performed by the upper limbs also depends on this feature. The structure of the human hand allows everyone to do a lot of the most diverse and quite complex operations - for example, to play the piano, draw, type texts on the keyboard. Such abilities in humans are due to the presence of many mobile joints. The structure of the hand allows you to firmly clamp objects.In particular, this is possible due to the design features of the thumb.
The structure of the hand includes many different sensory endings that create tactile sensations. Therefore, if she becomes numb, it is a sign that something is wrong with her. Possible reasons for this are squeezing of blood vessels, prolonged carrying of weights, or any work that involves lifting weights above the level of your heart. If numbness occurs too often, you should consult a doctor. It is possible that this is one of the manifestations of any serious illness.
The structure of the hand allows you to perform the most diverse work. This is largely due to the presence of nerves. There are three types of them: radial, ulnar, and central. The latter controls the accuracy of the grip and is responsible for the movements of the thumb, index and middle fingers. The ulnar nerve directs the fine motor skills of the hands. In addition, together with the central, it regulates muscle contraction.