6 THE SUPERIOR EXTREMITY 



convey sensory impulses only are the sensory nerve fibres. 

 The sensory nerve fibres which convey sensory impulses from 

 the skin are termed cutaneous nerves. 



The dissector of the upper extremity must begin work on 



Medial cutaneous branch of medial division of posterior ramus 

 Lateral cutaneous branch of medial division of posterior ramus > Medial division of 



Lateral division of posterior ramus dividing ^ 

 into terminal muscular branches' N 



Posterior ramus 



Anterior ramus 



Muscular branches x 



Posterior cutaneous 



branch of lateral 



division of 



anterior ramus 



Lateral division of 

 anterior ramus 



Anterior cutaneous 



branch of lateral 



division of 



anterior ramus 



\ Recurrent branch 

 S'ympathetic ganglion 

 Anterior division of anterior ramus 



posterior ramus 



, Posterior ganglionated 



root 



Posterior funiculus of 

 spinal medulla 



Posterior grey column 



Antero-lateral 

 funiculus 

 Anterior grey 

 column 



Medial cutaneous branch of anterior 

 division of anterior ramus 



Lateral cutaneous branch of anterior division of anterior ramus 



FIG. 4. Diagram of a Spinal Nerve. Note that the medial divisions of 

 the posterior ramus is represented as distributed to skin, whilst the lateral 

 division terminates at a deeper level in muscle. In some situations the 

 reverse condition occurs, and the medial and lateral divisions of all 

 posterior rami supply muscles. 



the fourth day after the subject has been placed in the 

 dissecting-room. He will find the body lying upon its back. 

 The thorax will be raised to a convenient height by means of 

 blocks, and a long board will be placed under the shoulders 

 for the purpose of supporting the arms when they are abducted 

 from the sides. 



