NERVES 



to the Infraspinatous muscle, besides some filaments to the shoulder-joint and 

 scapula. 



The Nerve to the Subclavius (n. subclavius) is a small filament, which arises from 

 the point of junction of the fifth and sixth cervical nerves; it descends to the muscle 

 in front of the third part of the subclavian artery and the lower trunk of the plexus, 

 and is usually connected by a filament with the phrenic nerve. 



The Long Thoracic Nerve (n. thoracalis longus; external respiratory nerve of Bell; 

 posterior thoracic nerve) (Fig. 816) supplies the Serratus anterior. It usually arises 

 by three roots from the fifth, sixth, and seventh cervical nerves; but the root from 

 the seventh nerve may be absent. The roots from the fifth and sixth nerves pierce 

 the Scalenus medius, while that from the seventh passes in front of the muscle. 

 The nerve descends behind the brachial plexus and the axillary vessels, resting 

 on the outer surface of the Serratus anterior. It extends along the side of the thorax 

 to the lower border of that muscle, supplying filaments to each of its digitations. 



The branches for the Longus colli and Scaleni arise from the lower four cervical 

 nerves at their exit from the intervertebral foramina. 



INFRACLAVICULAR BRANCHES. 



The infraclavicular branches are derived from the three cords of the brachial 

 plexus, but the fasciculi of the nerves may be traced through the plexus to the spinal 

 nerves from which they originate. They are as follows: 



Lateral cord 



Medial cord 



Posterior cord 



Musculocutaneous . . . 5, 6, 7 C. 



Lateral anterior thoracic . . 5, 6, 7 C. 



Lateral head of median . . . 6, 7 C. 



Medial anterior thoracic 



Medial antibrachial cutaneous 



Medial brachial cutaneous . 8 C, 1 T. 



Ulnar 



Medial head of median . 



Upper subscapular . . . . 5, 6 C. 



Lower subscapular . . . . 5, 6 C. 



Thoracodorsal 5, 6, 7 C. 



Axillary 5, 6 C. 



Radial 6, 7, 8 C, 1 T. 



The Anterior Thoracic Nerves (nn. thoracales anteriores) (Fig. 816) supply the 

 Pectorales major and minor. 



The lateral anterior thoracic (fasciculus lateralis) the larger of the two, arises 

 from the lateral cord of the brachial plexus, and through it from the fifth, sixth, 

 and seventh cervical nerves. It passes across the axillary artery and vein, pierces the 

 coracoclavicular fascia, and is distributed to the deep surface of the Pectoralis 

 major. It sends a filament to join the medial anterior thoracic and form with it 

 a loop in front of the first part of the axillary artery. 



The medial anterior thoracic (fasciculus medialis) arises from the medial cord of 

 the plexus and through it from the eighth cervical and first thoracic. It passes 

 behind the first part of the axillary artery, curves forward between the axillary 

 artery and vein, and unites in front of the artery with a filament from the lateral 

 nerve. It then enters the deep surface of the Pectoralis minor, where it divides 

 into a number of branches, which supply the muscle. Two or three branches pierce 

 the muscle and end in the Pectoralis major. 



The Subscapular Nerves (nn. subscapulares) , two in number, spring from the 

 posterior cord of the plexus and through it from the fifth and sixth cervical nerves. 



