The anatomy of the human hand is quite complicated.So, arteries, veins, nerves and muscles branch off and constantly intersect each other, and a network of tendons and ligaments react to each command of the brain. In addition, they easily bend and contract. The structure of the arm assumes a greater load on the muscles, since during the day a person produces a large number of different movements, and the shape of the hand depends on their condition.
All this complex hand construction is covered with leather,which serves as its protection against bacteria, toxic substances and radiation. It should be noted that it is waterproof, has the ability to maintain a certain body temperature and collect sensory information that comes from outside, so this hand structure allows you to accurately manipulate the objects with which this hand is in contact.
The lower layer of skin on the back of the hand is thin,so the hands freeze more often than other organs. The dermis on the back side has a small amount of sweat and sebaceous glands, which is why the skin dries more quickly. This layer of skin contains also nerves, lymphatic and blood vessels, as well as elastin and collagen, which make it firm and supple. However, ultraviolet, which penetrates through the dermis, has a negative effect on these two proteins, therefore the skin of the hands loses its elasticity and wrinkles form on it more quickly.
The structure of the human hand has somefeature. So, in the lower layer of the epidermis are cells that produce melanin. Thanks to it, the skin absorbs ultraviolet, thereby preventing its penetration into the dermis. If the sun's rays have a long-term effect on the skin of the hands, this leads to the formation of pigmented spots.
The structure of the hand of a person, includingwrists, can be treated as a separate chapter. They consist of twenty-seven bones that perfectly perform their functions, and tendons that attach muscles to the bones.
If we consider the skeleton of the brush, we can distinguish here eight bones forming the wrist, five bones forming a pastern (a brush), and fourteen bones that form the phalanges of the fingers.
The bones of the wrist form two rows of fourbones in each. The first row includes scaphoid and semilunar bone, and also trihedral and pea-shaped. The second row is bone-trapezoid, capitate and hook-shaped bone.
The bones of the hand consist of a base, a head (knuckles), and a body. The bones of the fingers consist of three phalanges, except the thumb (it has two phalanges).
Considering the structure of the hand, it should be noted that the muscles thatcontrol the wrist and brush, quite a lot. They are divided into front (responsible for flexion), rear (responsible for extension) and internal muscles (help to move the fingers).
The hand performs the following functions: grasping, precise coordinated movements, tingling.
Thus, the hand is attached to the body with the help ofbones, muscles and joints and consists of three parts: forearm, shoulder and hand. Bending at the elbow provides hands with great mobility and functionality, so we can make a variety of movements.
It should be noted that the ends of the fingers aresensory cells, through which a person learns the world through touch, which is why they are sensitive to pain. For their protection, there are nails, which are a horny plate, consisting of keratin, different from keratin skin. So, it is porous, harder and swells less when water gets on it.
The structure of the hand allows a person to know the world around him by touching and manipulating objects, which makes him different from other representatives of mammals.
