58 OUTLINES OF ANATOMY. 



Landmarks of the Back : 



Lumbar spines. 



Muscles. 



Trapezius. 



Latissimus dorsi. 



Triangle of Pettit. 



Origin of spinal nerves. 



Scapula, its muscles and arterial anastomoses. 



Lumbar fascia. 



Viscera, see table indicating the position of organs in cervical, thoracic, lumbar, and 



sacral regions. 



Dissection of the Posterior Cervical Structures and the Back. 



The dissector of the Uppet Extremity should participate in the dissection of the back, 

 until the dissection of the serratus magnus is completed. 



Make a median incision from the occipital protuberance to the sacrum. Make a transverse incision 

 from the spine of the seventh cervical vertebra to the end of the acromion process, also from the spine 

 of the last dorsal vertebra upward and outward to the same point. Make an incision from the spine 

 of the last lumbar vertebra to the crest of the ilium and along the. crest. Turn the skin outward from 

 the median line. The dissectors of the lower extremity will at the same time expose the sacral, coccy- 

 geal, and gluteal regions. The superficial lumbar, sacral, and coccygeal nerves should be noted by 

 the dissectors of the back, also. 



Superficial fascia, 302. (305) 

 Superficial nerves, Fig. 452; P. 826. (P. 807) 

 Cervical nerves, 825. (806) 



Internal branches, 3d, 4th, 5th. 

 Thoracic nerves, 827. (808) 



Internal branches from upper six or seven nerves. 

 External branches from lower five or six nerves. 

 Lumbar nerves, 827-8. (808) 



External branches of upper three nerves. 

 Sacral and coccygeal nerves, 828. (808-9) 



External branches of the upper three nerves. (See internal branches.) 

 Lower two sacral and the coccygeal nerve. 



The superficial arteries are derived from branches of the intercostal and lumbar 

 arteries and accompany the superficial nerves: 

 From intercostal arteries : 



Dorsal branch, 582; Fig. 362. (571-2) 



(ii) Muscular branch. 

 From lumbar arteries: 



Dorsal branch, 588. (577) 



Turn off the superficial fascia and expose the deep fascia. 



The deep fascia, 302. (305) 



Reflect the deep fascia from the surface of the trapezius and latissimus dorsi. 



Trapezius, 302-4; Fig. 262. (305-7) 



Origin. Insertion. Structure. Nerve-supply. Action. Relations. Variations. 



Divide the trapezius near its origin and turn outward to the insertion. Note the spinal accessory nerve 

 and the branches from the cervical plexus entering the deep surface of the muscle. 



Spinal accessory nerve, 819-20. (800-1) 

 Branches to the trapezius, 831. (812) 



Subtrapezial plexus. 

 Latissimus dorsi, 307-8; Figs. 262 and 269. (310) 



Origin. Insertion. Structure. Nerve-supply. Action. Relations. Variations. 



Divide the latissimus dorsi transversely on a line with the vertebral border of the scapula, reflect the 

 inner portion to the origin, note the relations, then remove the inner portion of the muscle. In the 



