THE HEAD AND NECK. 



In order to conform with the convenience of those who are engaged in 

 the examination of other parts of the body, the dissector of the head 

 and neck should begin with the structures that are ventral to the 

 cervical vertebrae. 



Before the removal of the skin, it will be observed that, in the lower 

 part of the neck, there is a single, median, elongated prominence 

 rounded from side to side, that divides into two rounded and divergent 

 ridges about the middle of the neck. This is formed by the two sterno- 

 cephalic muscles that, arising from the manubrium of the sternum close 

 together, gradually separate towards their individual insertions into 

 the mandible. Lateral to each muscle there is a groove, under which 

 the jugular vein will be discovered during the course of the dissection. 

 The groove is bounded laterally by the edge of the brachio-cephalic 

 muscle, and, if followed towards the sternum, will be found to become 

 very shallow just before it joins the supraclavicular fossa. 



Between the divergent sterno-cephalic muscles is an elongated 

 triangular area, slightly convex from side to side, formed by the trachea 

 and larynx (covered by a thin sheet of muscle) and continued forwards 

 between the two halves of the mandible. 



Dissection. — Make a longitudinal incision through the skin in the 

 midventral line from the manubrium of the sternum to the symphysis of 

 the mandible, and turn tlie skin aside as far as, or slightly beyond, the 

 edge of the brachio-cephalic muscle. The skin incision should be made 

 with care, otherwise the underlying cutaneous muscle — which is very 

 thin — will be injured, and there is even a risk that the muscle may be 

 unwittingly reflected along with the skin. 



Cutaneous nerves, derived from the cervical nerves from the second 

 to the sixth inclusive, will be found crossing the long axis of the neck at 

 fairly regular intervals. 



M. CUTANEUS COLLI. — Throughout the greater part of the neck 

 the cutaneous muscle is very thin, being composed of weak bundles that 

 run in an oblique cranial and lateral direction ; but a fairly sudden and 

 considerable thickening occurs in the region of the manubrium sterni, 

 from which the muscle may be said to take its origin. Laterally the 



