58 ANATOMY OF THE RAT 



origin cephalad to the occipital artery, then posteriorly, 

 sending branches to the thyroid gland, and one small branch 

 to the larynx. 



(3) The Ungual artery leaves the external carotid an- 

 terior to the superior thyroid artery, enters the posterior 

 region of the tongue, and follows a sinuous course nearly 

 to the tip in the ventral part of that organ. 



(4) The external maxillary or facial artery leaves the 

 external carotid a short distance anterior to the lingual 

 artery, and passes anteroventrally along the medial sur- 

 face of the masseter muscle. Anteriorly it occupies the 

 groove between the masseter and digastric muscles. It 

 bifurcates about half a centimeter back of the angle be- 

 tween the upper and lower lips. The dorsal ramus sup- 

 plies the snout and lateral wall of the mouth. The ventral 

 ramus supplies the lower lip. This artery sends vessels to 

 the lymph and salivary glands of the neck region, to the 

 masseter muscle, the ventral musculature of the lower jaw, 

 and the floor of the posterior region of the buccal cavity. 



(5) Posterior auricular artery. The external carotid 

 artery turns abruptly dorsally immediately after giving off 

 the external maxillary. It turns anteriorly again ven- 

 trolateral to the tympanic bulla. The posterior auricular 

 artery arises at the latter turn. It courses dorsally along 

 the posterior surface of the external auditory meatus to- 

 the pinna of the ear, to which it sends branches. It also 

 supplies the muscles adjoining the pinna. Trace the termi- 

 nal branches of the external carotid. 



The innominate artery is the first arterial trunk leaving 

 the aortic arch. A short distance from its origin the in- 

 nominate divides into the right common carotid and the 

 right subclavian arteries. The subclavian passes antero- 

 laterally to the anterior surface of the first rib, where, in 

 company with the nerves of the brachial plexus, it leaves 



