DISSECTION OF THE NECK 343 



VIII. DISSECTION OF THE NECK. 



A special dissection of the neck is desirable on account of 

 the great importance of the structures contained in it, more 

 particularly the nerves. 



Lay the rabbit on its bach on a dissecting -boa/rd ; and pin 

 back the head so as to extend the neck strongly. Make a 

 median ventral incision through the skin of the neck, and 

 dissect the skin omay from the underlying parts, taking care 

 not to damage these. 



A. The Hyoid Bone. 



The body of the hyoid is a transverse bar of bone, deeply 

 placed between the rami of the mandible, and about midway 

 between the binder end of the mandibular symphysis and the 

 angles of the jaw. 



The posterior comua of the hyoid are a pair of slender 

 rods of bone, about half an inch long, running backwards and 

 outwards from the outer angles of the body of the hyoid, 

 parallel to the angles of the jaw. 



Determine the position and shape of the hyoid by feeling 

 with the finger. 



B. The Trachea. 



The trachea or windpipe is a straight tube, running down 

 the neck almost in the middle line. It is only partially 

 exposed at present, but will be seen better in the course 

 of the dissection. Its anterior end, which is placed almost 

 immediately behind the hyoid, is dilated, and surrounded on 

 the ventral and lateral surfaces by the wide thyroid cartilage, 

 which forms a prominent swelling in the throat, placed 

 between the rami of the mandible and readily identified 

 by the finger. Behind this is the annular cricoid cartilage, 

 which is wide dorsally and narrow ventraUy. Behind the 

 cricoid the trachea narrows slightly, and is surrounded by a 

 series of cartilaginous rings, incomplete along the mid-dorsal 

 line. The trachea runs backwards along the neck, and, 

 entering the thorax, divides about the level of the middle of 



