Page 72 - ASOP ROT Study Guide

11 . 7 Nerve Supply

There are three nerves which control the movement of the wrist and hand:

♦ Median nerve
♦ Ulnar nerve
♦ Radial nerve

The radial nerve controls the extensor muscles. The medial and ulnar nerves control the flexor
muscles.

12. THE HAND

Our study of the upper limb has now brought us to its termination and the reason for its great
mobility ... the hand.

Three characteristics make the hand very important to humans:

♦ Motor control - the musculature and nervous control to enable the execution of fine precision
movements as well as strong grasping actions.

♦ Sensory ability - the highly developed sensory ability of the thumb, index and middle fingers
have earned them the title of "the eyes of the hand".

♦ The thumb - without the ability of the thumb to touch the tips of the other digits, we would be
less able to benefit from the previous two abilities of the hand.

12 . 1 Shape and Stability

The hand is made up of five metacarpal bones based on the carpal bones. The individual bones of
the fingers and thumb are called phalanges. These bones are held together by ligaments. Stability
of the joint between the metacarpal bones and the carpal bones is due to their shape and
Unit 2 - Skeletal Anatomy and Physiology 27
ligamentous supports. Ligaments stretching between the metacarpal heads secure the metacarpals
together at the knuckle area. In the fingers the phalanges are supported by collateral ligaments at
each joint. These are arranged so as to allow hinge movements only. Consequently there is some
weakness in an antero-posterior direction. Dislocation of the joints between the phalanges is
possible.

The hand has the ability to conform to a variety of shapes. It can become broad and flat or long
and narrow. It can make a fist or cup itself around a ball. The thumb can be used with the tip of
any finger to pick up objects of different sizes.