DISSECTION OF THE BACK 4? 



of the long thoracic nerve. It pierces the scalenus medius, 

 and then proceeds downwards, under cover of the levator 

 scapulae, to the deep surface of the rhomboidei muscles to which 

 it is distributed. The dorsalis scapulae nerve likewise supplies 

 one or two twigs to the levator scapulae. 



The dorsalis scapulae nerve sometimes pierces the levator 

 scapulae in two or more branches, which unite in a plexi- 

 form manner. 



Ramus Descendens of the Art. Transversa Colli (O.T. 

 Posterior Scapular Artery). The descending branch of the 

 transverse cervical artery takes origin in the lower part of 

 the neck close to the lateral margin of the levator scapulae. 

 At first it proceeds medially under cover of this muscle, but 

 soon changing its direction it runs downwards along the base 

 or vertebral border of the scapula under cover of the rhomboid 

 muscles (Fig. 17, p. 39). It gives numerous branches to both 

 costal and dorsal aspects of the scapula, and its terminal 

 twigs may enter the latissimus dorsi. One large branch 

 usually passes backwards, in the interval between the rhomboid 

 muscles or through the greater rhomboid, to reach the trapezius 

 muscle ; and another branch, the supraspinal, is given to the 

 supraspinatus muscle, and the structures superficial to it. 



Reflection of Latissimus Dorsi. Divide the muscle by carrying the 

 knife from its upper margin, about three inches from the vertebral spinesj 

 obliquely downwards to a point a little way behind its digitation from 

 the last rib. In raising the medial portion of the muscle care must be 

 taken of the subjacent serratus posterior inferior. The attachment of the 

 latissimus dorsi to the crest of the ilium and to the lumbar aponeurosis 

 can now be verified. The lateral part of the muscle is next to be thrown 

 forwards, so that the three costal digitations may be seen from their deep 

 aspect, and also for the purpose of displaying the termination of the sub- 

 scapular artery and the thoracodorsal nerve. These are found upon 

 the deep surface of the muscle at the inferior angle of the scapula. 



The Removal of the Upper Extremity. After the costal 

 attachments of the latissimus dorsi have been displayed the 

 upper extremity must be removed. Draw the extremity 

 away from the body ; detach the costal slips of the latissimus, 

 cut through the serratus anterior about one inch from the 

 vertebral border of the scapula ; divide the dorsal scapular 

 nerve, the ramus descendens of the transverse cervical artery, 

 the posterior belly of the omo-hyoid muscle, the transverse 

 scapular artery and the suprascapular nerve. Cut through 

 the axillary vessels and the cords of the brachial plexus at the 

 lateral border of the first rib ; detach the anterior skin flap 



