368 DISSECTION OF THE BABBIT. 



and oesophagus. These are of small size, and 

 are given off in the thorax : the cardiac branches 

 end in a plexus, lying between the roots of the 

 aorta and pulmonary artery. 



Turn the lungs and heart over to one side : follow th 

 2>netimogastrtc backwards through the thorax, alongside tht 

 cesophagus, and trace out its branches. 



4 . The cervical sympathetic nerve lies alongside the trachea, 



to the inner side of the carotid artery, and in close 

 proximity to the depressor nerve. 



About the level of the angle of the jaw, and dorsal 

 to the stylo-hyoid muscle, it has a small oval swell- 

 ing, the anterior cervical ganglion, and at the pos- 

 terior end of the neck, a short distance in front of 

 the subclavian artery, there is a similar swelHng, the 

 middle cervical ganglion. 



The sympathetic nerves are of a pale pinkish colour, and 

 are not nearly so easy to see as the white cords of the ptietimo- 

 gastric and its branches. 



5. The great auricular nerve is a large branch of the third 



spinal nerve, given off immediately after the nerve 

 emerges from the spinal canal, between the second 

 and third cervical vertebrae. It runs vertically up- 

 wards to the base of the ear, lying along the posterior 

 border of the parotid gland (p. 375), and about half 

 an inch behind the angle of the jaw : it then runs 

 along the outer surface of the pinna of the ear, as 

 far as its tip, lying just beneath the skin. 



The nerve can easily be felt as a cord running along the 

 pinna, or seen by holding the ear up to the light, and looking 

 through it. 



Having determined its position in one of these ways, cut 

 down upon it, and follow it to the tip of the ear, and down- 

 wards to its point of origin from the third spinal nerve. 



6. The phrenic nerve is a branch of the fourth cervical 



nerve, which arises just beyond the point of emer- 



