DISSECTION OF THE BACK 61 



Nervus Dorsalis Scapulae (O.T. Nerve to the Rhomboids). 



This long slender nerve arises, in the neck, from the fifth 

 cervical nerve, usually in common with the upper root of 

 the long thoracic nerve. It pierces the scalenus medius, 

 and passes downwards, under cover of the levator scapulae, 

 to the deep surface of the rhomboidei muscles. It ends in 

 those muscles, but it supplies, also, one or two twigs to the 

 levator scapulae. 



The root twigs of origin of the dorsalis scapulae nerve 

 sometimes pierce the levator scapulae separately, and then 

 unite in a plexiform 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 runs medially .under cover of the levator scapulae, 

 but it soon changes its direction and then runs downwards 

 along the vertebral border of the scapula, under cover of the 

 rhomboid muscles (Fig. 26, p. 52). It gives numerous branches 

 to both the 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. 



Dissection. Reflection of the Latissimus Dorsi and the 

 removal of the Superior Extremity. Divide the latissimus dorsi. 

 Commence the division at the upper border three inches from the 

 vertebral spine, and carry the knife obliquely downwards and 

 laterally to a point just below where the last digitation of the 

 muscle springs from the last rib. Remember that the muscle is 

 thin, and do not injure the parts subjacent to it. Turn the 

 medial portion towards the vertebral spines, taking care not to 

 injure the serratus posterior inferior in the region of the lower 

 four ribs, and verify the origin of the muscle from the spines 

 and supraspinous ligaments, lumbar fascia and iliac crest. 

 Throw the lateral part of the muscle laterally and forwards, 

 clean the deep surfaces of the slips attached to the lower three 

 or four ribs, and note that they interdigitate with the ex- 

 ternal oblique muscle of the abdomen. At the inferior angle 

 of the scapula find the thoraco-dorsal nerve and the thoraco- 

 dorsal artery. They supply the muscle and enter its deep 

 surface. 



The Removal of the Superior Extremity. (i) Divide the 

 transverse scapular artery and the suprascapular nerve and the 



