The Shoulder Region

Abstract

Man is the only primate in whom the upper limb normally has almost no locomotor function. The upper limb is completely free for use in grasping and moving objects and also for carrying out skilled, accurate, delicate movements such as are involved in writing and many occupations. For this purpose the hand has an especially rich nerve supply both motor and sensory. These skills depend, however, on the large motor and sensory representation of the hand in the human cerebral cortex. It has been suggested that the characteristic upright posture adopted by man probably more than two million years ago freed the upper limb for additional functions and, as a result of this, the human brain developed and enlarged into its present form.