THE RABBIT. 313 



the larynx, and, at about the level of the anterior end oi' 

 the larynx, divides into the internal carotid (/.c), which 

 passes dorsalwards to reach the brain, and the external 

 carotid {e.tr), which supplies the greater part of the head : 

 the internal carotid may be recognised as being the first 

 important branch given off from the outer side of the 

 common carotid : the external carotid divides almost 

 immediately into, branches (or the jaws, eye, &c. 



244. The cervical portion of the vagus, a nerve running 

 to the outer side of each common carotid. 



Traced backwards, the right vagus is seen to pass across (ventral to) 

 the ri^ht subclavian artery, the left across the arch of the aorta, to 

 enter the thorax, where they have already been seen (§ 236). 



245. The cervical portion of the sympathetic, seen by lifting up 

 the carotid and carefully separating it from the vagus : it is a flat pale 

 nerve lying immediately dorsal to the artery : traced backwards, it 

 enlarges at about the level of the first rib into the posterior cervical 

 ganglion, and thus enters the thorax, where it has already been seen. 



246. Traced forwards, the sympathetic is seen to enlarge, at a level 

 just anterior to the larynx, into the anterior cervical ganglion, im- 

 mediately external to which is a similar enlargement of the vagus, the 

 ganglion of the root: crossing both nerves and the carotid artery at 

 about the same level, but obliquely from behind forwards and inwards, 

 is the slender tendon of the digastric muscle, and i.iimediately 

 behind and parallel to this the hypoglossal nerve. 



247. The thyroid gland, a brownish mass, consisting 

 of two lobes applied to the sides of the larynx, and con- 

 nected across the ventral face of the latter by a band-like 

 intermediate portion. 



248. The large thyroid cartilage, forming the anterior 

 part of the larynx, and the ring-like cricoid cartilage, 

 forming its posterior part. 



249. The submaxillary gland has been already seen : its duct 

 (Wharton's duct) is a very fine tube proceeding from its inner face to 

 open on the floor of the mouth. 



