The hands are the gripping organs of humans. It is located on the upper extremities and enables the so-called tweezer grip through the thumb. Also of it the hand is one of the most important body parts.
What are hands?
Hands are the gripping organs on the upper extremities. Both humans and some primates have hands, although the thumb is reserved for only a few species of monkeys. Hands are needed to grasp things, crush things, or do other work. They are also an important part of communication. The human hand can be affected by various diseases in addition to various fractures. Some deformities may also be congenital.
Anatomy and structure
Anatomically, the hand consists of 27 individual bones. Thereby, the carpus consists of the carpal bones, i.e. scaphoid bone, capitate bone, lunate bone, greater polygonal bone, lesser polygonal bone, pea bone, triangular bone and hook. These bones are articulated together and lie in two rows. They form the distal wrist. In addition, there is also the proximal wrist joint, which lies triangular bone, scaphoid bone, lunate bone and radius. It is much more significant for the functional use of the hand. Next to the carpus lies the metacarpal, which in turn consists of five elongated metacarpal bones. Lastly, the hand consists of five fingers, which are freely movable. They consist of a total of 14 finger bones, whereby the thumb is formed from two bones and the other fingers from three bones. While the bones form the basic framework for the human hand, the muscles are essential for movement. The musculature in the hand consists of 33 muscles. The majority, however, are located in the forearm and only send their tendons into the hand. In addition, the so-called thenar muscles on the side of the thumb and the hypothenar muscles on the side of the little finger are located in the hand. Muscles also lie between the metacarpal bones. In addition to muscles and bones, the hand is traversed by three nerves. The ulnar nerve, the median nerve and the radial nerve. They are part of the carpal tunnel and enable blood supply. The skin and veins are also a part of the hand.
Function and tasks
The hand basically has the function of grasping things. There are two different types of grips. First, there is the power grip, which is used for heavy and large objects. The other is the precision grip for fine instruments and small objects. The power grip uses the entire palm of the hand, including the fingers and thumb. This makes it possible to hold larger objects and guide them with optimal force. The force that can be exerted is several hundred newtons. If the thumb is not used, this is also referred to as the monkey grip. The precision grip is made possible by the fingertips of the thumb and index finger. Sometimes the tip of the middle finger is also used. Depending on the size of the element to be moved, one speaks of the tweezer grip, the pincer grip, the key grip or the three-point grip. In addition, the hand can be clenched into a fist, which in earlier times brought a great fighting advantage. Nowadays, these functions are rarely used for survival purposes. The curving of the hand is also an important function. Especially when scooping water and similar activities. Furthermore, the hands are used for communication. From simple pointing to gestures to sign language and other signal systems, the hands have a great use here. In particular, in the computer age, the hands and especially the fingers are indispensable for typing on keyboards and using touch-sensitive screens.
Diseases and ailments
In addition to various bone fractures and tendon injuries, the hands can also be affected by nerve diseases and other ailments. These include, for example, rheumatism of the tendons or joints of the hand or sulcus ulnaris. This is a pressure damage of the ulnar nerve. Furthermore, the so-called fast finger can occur. This syndrome is expressed by the fact that the finger moves uncontrollably. If the nerves are injured, the hands or individual fingers may become stiff. These damages are difficult to treat even with modern surgical means. Tendon injuries are just as serious and cannot always be completely healed. If tumors occur in the hand, treatment is possible in most cases.Furthermore, lunate bone death, lunate bone cysts, ganglions (swellings) or an enchondroma may occur. Congenital malformations such as syndactyly, in which the fingers are fused together, are among the more serious syndromes. Likewise, a congenital bending position of the thumb. Due to the mentioned complaints in the area of the hands, great problems occur in everyday life. Surgical measures can remedy congenital damage at least partially or completely.
