Hand Anatomy
There are 27 bones in your hand. These bones are connected by ligaments, tendons, and muscles that allow you to do things like type, grip things, and many other activities. This article will attempt to give a basic overview of the anatomy of the hand.
Bones
There are three types of bones in the hand and wrist: carpals, metacarpals, and phalanges. There are 8 carpal bones in your wrist. These make part of the wrist by meeting two bones in the forearm. There are 5 metacarpals in your palm. These connect to the phalanges to make your fingers and thumb. Finally, there are 14 phalanges in your fingers. These serve to form your fingers.
Soft Tissue
The surfaces where the bones meet, or joint surfaces, are covered with a smooth material called articular cartilage to facilitate ease of movement. Collateral ligaments, tough tissue structures, are on either side of each finger and thumb joint to prevent unusual movement or bending. Extensor tendons in each finger joint allow for the joint to straighten. These tendons travel from the forearm to the fingers, where they form the extensor hood to cover the tops of the fingers. The area in which the extensor tendon meets the middle joint is called the central slip. In each of the middle joints of the fingers, there is a ligament called the volar plate that prevents the joint from hyperextending.
There are also many muscles in the hand that allow for actions like gripping, holding, and creating fine motions of the hand and fingers. Many of the muscles responsible for gripping and other actions actually originate in the forearm. The intrinsic muscles are the smallest muscles originating in the wrist and hand, and they are responsible for positioning and steadying the hand during fine motions.
Nerves
There are three nerves that run through the hand. These are the radial and median, and ulnar nerves, and they travel from the cervical section of the spinal column, through the arm, into the hand, and through the fingers. The radial nerve runs along the side of the forearm that the thumb is on, giving sensation to the back of the hand from the third finger to the thumb. The median nerve travels through the carpal tunnel, a tunneled area within the wrist. It gives sensation to the thumb, index finger, middle finger, and half of the ring finger. The median nerve also helps to control muscle movement in the thumb. The ulnar nerve travels through a separate tunnel in the wrist, then the median nerve. It provides sensation in the other half of the ring finger and in the little finger, as well as helping with muscle movement of the thumb and palm.