THE NERVES. 



407 



3. Nn. tkoracici anteriores, arise from the anterior portion of 

 the brachial plexus, above the m. subclavius, from the fifth to 

 seventh cervical nerves, pass inwards, before and behind art. 

 axillaris to m. pectoral, major and minor ; a filament along the 

 clavicula. Branches : to m. subclav., deltoid., even to the skin of 

 the mammary gland. 



4. JV. suprascapularis arises from the fifth, and is enlarged by 

 the sixth and seventh cervical nerves, passes backwards, outwards, 

 and downwards along the m. t omo-hyoid. and with the vena 

 transversa scap. goes through the incisura scapul., beneath the 

 lig. transvers.j whilst the artery passes over it. (In consequence 

 of becoming enlarged the vein presses upon this nerve ; hence 

 pains about the shoulder in diseases of the heart.) It supplies m. 

 supra- and infra-spinatus. 



5. Nn. subscapulares, two branches, arise from the fifth to 

 seventh cervical nerves, sometimes from n. axillaris, pass back- 

 wards and downwards, giving branches to m. teres major, and 

 sinking into m. subscapularis. 



6. N. marginalis scapulce s. subscapularis longus, arises from 

 the inferior central part of the plexus, passes with art. subscapul. 

 to the outer border of the shoulder blade, giving branches to : m. 

 serrat. antic, maj. and latiss. dorsi. 



658. b. The nerves of the arm, branches of the pars axillaris 

 of the brachial plexus. 



There are three cutaneous and four muscular nerves. 

 Of these, the 



N. Axillaris supplies 



_ZV. musculo-cutaneus 

 N. radialis 



N. medianus and ulnaris 



the m. deltoideus and teres 

 minor ; 



the flexors of the fore-arm ; 



the extensors of the fore- 

 arm and the hand, and 

 the supinators ; 



the flexors and prona- 

 tors of the hand and 

 finders. 



659. 



Cutaneous nerves. 



1. N. cutaneus brachii internus (minor s. ulnaris), arises from 

 the loops of the seventh cervical and first dorsal nerves, passes 

 into the axilla on the internal posterior side of ven. axillar., then 

 on the internal side of the humerus, perforates the fasc. brachial. 

 in the middle third and inclines outwards. It supplies above, the 



