216 LABORATORY MANUAL OF HUMAN ANATOMY 



(aa) Supraclavicular part (pars supraclavicularis ) . 



(aaa) Posterior thoracic nerves (Nn. thoracales poste- 



rior es). 



(1) Dorsal nerve of scapula (N. dorsalis scap- 



ulae) (0. T. nerve to the rhomboids). 



(2) Long thoracic nerve (N. thoracalis longus) 



(0. T. external respiratory nerve of Bell, 

 or posterior thoracic). 



(aab) Anterior thoracic nerves (Nn. thoracales ante- 



rior es}. 



(aac) Subclavius nerve (N. subclavius). 



(aad) Suprascapular nerve (N. suprascapularis) . 



(aae) Subscapular nerves (Nn. subscapulares) . 



(aa/) Thoracodorsal nerve (N. thoracodorsalis) (0. T. 



long subscapular nerve). 



(aag) Axillary nerve (N. axillaris) (0. T. circumflex 

 nerve). 



(1) Muscular branches (rami musculares) . 



(2) Lateral cutaneous nerve of arm (N. cuta- 



neus brachii lateralis). 



Surgical Anatomical Points. 



Note that the supraclavicular triangle is the " seat of election" for liga- 

 ture of the subclavian artery; its relations to neighboring structures are, 

 therefore, exceedingly important. Examine these carefully, using your 

 text-book as a guide. Note especially the relation of the artery to the 

 external jugular vein and its tributaries. Run the finger down the lateral 

 margin of the M. scalenus anterior (just beneath the posterior margin of 

 the M. sternocleidomastoideus) until the scalene tubercle (tuberculum 

 scaleni) on the first rib is reached. This is the guiding-point for the 

 surgeon in the operation of ligation. If the finger-nail rest on the tuber- 

 culum scaleni, the artery will be felt, in the living subject, to pulsate 

 against the finger-pulp. The proximity of the lowest trunk of the plexus, 

 brachialis and of the cupula pleurae to the artery are important points- 

 to the surgeon. If a cervical rib be present, the artery may either be in 

 front of it or arch above it. 



The V. jugularis externa is often opened in the posterior triangle to 

 relieve the right heart in asphyxia; its position corresponds to a line 

 drawn from the angle of the jaw to the middle of the clavicle. It should 

 not be opened in the lower part of its course, where it is held open by the 

 fascia, owing to the danger of suction of air into the vessel during inspi- 

 ration. 



How is the floor of the supraclavicular triangle formed? 



Anterior Triangle of the Neck. (Vide Figs. 87 and 91.) 



Turn the N. cutaneus colli and the ramus colli N. facial is 

 backward and remove the superficial and deep layers of the 

 fascia colli. Note that the deep layer does not extend above 

 the omohyoid muscle or the hyoid bone. How is the anterior 



