292 THE SPINAL NERVES. 



Varieties. The communicating branch to the phrenic nerve has been seen to pass down 

 into the thorax over the subclavian artery, and even over the vein, before joining- with the 

 trunk. A second filament to the, phrenic, from the sixth nerve, is rarely met with. 



The branch for the rhomboid muscles (n. dorsal-is scapula) arises in 

 common with the highest root of the posterior thoracic nerve from the fifth nerve 



Fig. 193. DEEP DISSECTION OF THE AXILLA, SHOWING THE BRACHIAL PLEXUS AND NEIGHBOURING 

 NERVES. (From Sappey, after Hirscbfeld and Leveille.) . 



The clavicle has been sawn through near its sternal end, and is turned aside with the muscles 

 attached to it ; the subclavius and the greater and lesser pectoral muscles have been removed from the 

 front of the axilla. 1, ansa cervicalis ; 2, pneumo-gastric ; 3, phrenic, passing down to the inner side 

 of the scalenus anticus muscle ; 4, anterior primary division of the fifth cervical nerve ; 5, 6, 7, the 

 same of the sixth, seventh, and eighth cervical nerves ; 8, the same of the first dorsal 'nerve ; 9, 9, 

 nerve to the subclavius muscle, communicating with the phrenic nerve ; 10, posterior thoracic nerve 

 distributed to the serratus magnus ; 11, external anterior thoracic nerve, passing into the great pectoral 

 muscle; 13, internal anterior thoracic, distributed to the lesser pectoral ; 14, twig of communication 

 between these two nerves ; 12, suprascapular nerve, passing through the suprascapular notch ; 15, 

 upper subscapular nerve ; 16, lower subscapular nerve ; 17, long subscapular nerve ; 18, 21, small 

 internal cutaneous nerve ; 19, union of this with the second and third intercostal nerves ; 20, lateral 

 branch of the second intercostal ; 22, internal cutaneous nerve ; 23, ulnar nerve to the inside of 

 the axillary artery, passing behind the vein, and having, in this case, a root from the outer cord of 

 the plexus ; 24, median nerve immediately below the place where its two roots embrace the artery, 

 which is divided above this place ; 25, musculo-cutaneous nerve, passing into the coraco-brachialis 

 muscle, to which it is giving a branch ; 26, musculo-spiral nerve, passing behind the divided axillary 

 artery. 



close to the vertebrae, and is directed backwards to the base of the scapula through 

 the fibres of the middle scalenus, and beneath the levator anguli scapulae, to the 

 deep surface of the rhomboid muscles, in which it terminates. It gives one or two 

 branches to the levator scapulae, and sometimes a twig to the highest digitation of 

 the serratus posticus superior (Rielander). 



