CEREBRO-SPINAL NERVES 399 



4. Nerve to the Subscapularis. 



5. Nerves to Serratus Magnus and Levator Scapulae. 



6. The Circumflex Nerve. 



7. Nerves to Teres Major and Latissimus Dorsi. 



8. The Musculo-spiral Nerve. 



9. The Median Nerve (two roots). 



10. The Ulnar Nerve. 



11. The Subcutaneous Thoracic Nerve. 



The Phrenic or Diaphragmatic Nerve is formed mainly by the 



union of the sixth and seventh cervical nerves, and sometimes also by a 

 small branch of the fifth. It then enters the chest by passing between the 

 two first ribs, and crossing the pericardium reaches the diaphragm, where 

 it terminates. It is a motor nerve to the diaphragm. 



The Suprascapular Nerve is short and somewhat thick. It is 

 derived from the sixth, seventh, and eighth cervical roots, and passes 

 between the supraspinatus muscle and the subscapularis. After winding 

 round the anterior border of the scapula it gives branches to the supra- 

 spinatus, and is ultimately expended in the infra-spinatus. 



The Anterior Deep Pectoral Muscle receives its nerve supply from 

 the seventh and eight cervical nerves, while the superficial pectoral muscle 

 obtains^ its fibres from the two roots of the median. A branch also passes 

 to the posterior deep pectoral, and another longer and thicker follows the 

 course of the spur vein. 



Nerve to the Subscapularis. All the cervical roots of the brachial 

 plexus contribute to form the nerve going to the subscapularis. After 

 crossing the supra-spinatus some of the fibres pass between it and the 

 subscapularis, and the rest are distributed to that muscle. 



Nerve to Serratus Magnus is derived from the seventh and 

 eighth cervical nerves, which pass through the upper division of the 

 scalenus muscle, and uniting distribute branches to the serratus magnus 

 muscle. 



Nerve Of the Teres Major is a small nerve situated beneath the 

 shoulder on the inner face of the subscapularis. It springs from the 

 seventh and eighth pairs in common with the circumflex nerve, and gives 

 its fibres to the teres major. 



Latissimus Dorsi branch. A long nerve situated beneath the 

 scapula, and derived mainly from the root of the eighth cervical nerve, 

 and to some extent also from the dorsal roots of the brachial plexus. 



It crosses the subscapularis and teres major to gain the latissimus dorsi, 

 where its fibres are expended. 



Nerves to the Levator Anguli Scapulae. The levator anguli 

 scapulae, together with the rhomboideus, receive their supply from the 



