DISSECTION OF THE HEAD AND NK< K 



triangle of the neck bounded? Locate (a) superior belly of 01110- 

 liyoid muscle (venter superior M. omohyoidei), (b) digastric 

 muscle (M. digastricus), and (c) stylohyoid muscle (M. stylo- 

 liyoideus). Clean their surfaces, but avoid injury to (1) the 

 branches of the ramus descendens N. hypoglossi entering the 

 upper border of the venter superior M. omohyoidei, (2) the 

 anterior and posterior facial veins (Vv. faciales anterior et pos- 

 terior) where they unite to form the common facial vein (V. 

 facialis communis) on the posterior belly of the M. digastricus, 

 and (3) the mylohyoid nerve (N. mylohyoideus) entering the 

 upper border of the venter anterior of the M. digastricus. When 

 these muscles have been thoroughly cleaned, it will be noticed 

 that they divide the anterior triangle of the neck into three sub- 

 sidiary triangles from above downward : 



(a) Submaxillary or digastric triangle. 



(b) Carotid triangle (sometimes called "superior carotid" triangle). 



(c) Muscular triangle (sometimes called "inferior carotid" triangle). 



Review the boundaries of these three triangles. Note espe- 

 cially that the muscular triangle is covered by both the super- 

 ficial and deep layers of the fascia colli, the digastric and carotid 

 triangles by the superficial layer only. 



The anterior triangle should be dissected as a whole, rather 

 than the subsidiary triangles one by one ; the structures passing 

 through more than one triangle are then studied in their con- 

 tinuity. The areolar tissue binding arteries, veins, nerves, and 

 muscles together is to be removed bit by bit. Atlases should be 

 open before the student constantly; as soon as a structure 

 exposed, it should be identified by reference to the plates in the 

 atlases and the name repeatedly associated with it as it is further 

 handled. From time to time, a description of all structure! 

 exposed should be read in the systematic text-book. It i 

 helpful to write down in full each new term met with m order 1 

 learn it more quickly and surely. It will be found 

 majority of the structures can be exposed without 

 through any muscle or larger vessel or nerve. 



Submaxillary or Digastric Triangle. (Vide Fig. 113, P- 266.) 



It is arbitrarily subdivided into an anterior and a posterior 



portion by the stylomandibular ligament (ligamentum stylon^n 



dibulare) (0. T. stylomaxillary ligament) (cf. Spalteholz, v 



Fig. 206) and a line drawn downward from it. 

 In the anterior portion find 



