32 THE UPPER EXTREMITY 



N. thoracodorsalis (O.T. Long Subscapular) (from C. vi., vn., 



VIII.). 



N. axillaris (O.T. Circumflex) (from C. v., vi.). 

 N. radialis (O.T. Musculospiral) (from C. v., vi., vn., vin. i). 

 In the above table the different spinal nerves from which the fibres 

 of the several branches are derived are indicated. 



Nervi Thoracales Anteriores (Anterior Thoracic Nerves). 

 These are the nerves which supply the pectoral muscles. 

 They are two in number, the lateral and the medial. The 

 lateral springs from the lateral cord of the plexus, passes 

 forwards across the lateral side of the first part of the axillary 

 artery, anastomoses in front of the artery with the medial 

 nerve, pierces the costo-coracoid membrane, and breaks up 

 into branches which end in the pectoralis major. The medial 

 anterior thoracic nerve is somewhat smaller than its lateral 

 companion. It springs from the medial cord of the plexus, 

 passes forwards between the axillary artery and vein, anasto- 

 moses in front of the artery with the lateral nerve, gives 

 twigs of supply to the pectoralis minor, then pierces that 

 muscle and ends in the pectoralis major which it also supplies. 

 The pectoralis major is, therefore, supplied by both anterior 

 thoracic nerves, the pectoralis minor by the medial nerve 

 alone. 



Nervi Subscapulares (Subscapular Nerves). The sub- 

 scapular nerves are also two in number the upper and the 

 lower. They both spring from the posterior cord of the plexus. 

 After a very short course the upper nerve sinks into the upper 

 and posterior part of the subscapularis which it supplies. The 

 lower Subscapular nerve passes downwards and laterally, gives 

 branches to supply the lower part of the subscapularis, then 

 passes through the angle between the Subscapular artery and 

 its circumflex scapulae branch and ends in the teres major 

 which it supplies. 



Nervus Thoracodorsalis (O.T. Long Subscapular Nerve). 

 This nerve springs from the posterior cord of the plexus, passes 

 obliquely downwards and laterally, through the axilla, and 

 joins the Subscapular artery near the lower part of the lateral 

 border of the subscapularis muscle. After crossing in front 

 of the artery it terminates in the latissimus dorsi which it 

 supplies. 



Nervus Thoracalis Longus (O.T. Posterior Thoracic or 

 External Respiratory Nerve of Bell). The long thoracic 

 nerve may now be studied in its whole length. It passes 



