146 THE SURGICAL PHYSIOLOGY 



than most of us can carry conveniently in our 

 memories. It is hoped that the bare elements set 

 down below may be found easier to remember, and 

 adequate for most purposes. No two accounts agree 

 exactly. 



The main points may be emphasized first. With 

 regard to the sensory distribution, there is a good 

 deal of overlap, especially in the hand, where the 

 seventh cervical supplies the radial half, the eighth 

 cervical the inner half, and the first dorsal the one 

 and a half fingers to which the ulnar nerve may be 

 traced. The twelve dorsal nerves supply the chest 

 and abdomen in bands like successive strips of 

 plaster stretched round the body ; the nipple lies 

 between the fourth and fifth dorsal, and the umbilicus 

 between the ninth and tenth. If we place the open 

 hand on the thigh just below and parallel to Poupart's 

 ligament, we cover the first lumbar area ; the next 

 handbreadth below is the second lumbar, and the 

 next, including the region of the patella, is the third 

 lumbar. The small sciatic nerve area corresponds to 

 the second sacral. 



With regard to motor distribution, the fifth cervical 

 supplies the deltoid + biceps + supinator longus group, 

 as well as the dorsal scapular muscles and rhomboids. 

 In infantile palsy and other anterior horn or nerve- 

 root affections, these muscles may be found paralysed 

 and atrophied in company. On the other hand, a 

 fracture of the spine irritating this area brings 

 about a characteristic position of the arms ^ . The 

 first dorsal gives off sympathetic branches dilating 

 the pupil. The hand and foot are each supplied by 



