is8 



ELEMENTS OF MAMMALIAN ANATOMY 



forming the right common carotid and the left common carotid, 

 lying on the respective sides of the trachea beneath the sterno- 

 mastoid and the sternohyoid muscles. The vagus or tenth 



Fig. 79. — Ventral Aspect of the Arteries of the Head and Neck. 

 The carotids with their branches have been drawn laterad. 

 a. Internal maxillary; ac, anterior cerebellar; ce, median cerebral; cr, posterior 

 cerebral; cp, posterior cerebellar; ex, carotid plexus, many of whose branches 

 reunite in one; ex', which is cut off; ex, external carotid; em, external maxillary; 

 ine, origin of internal carotid; inc', union of internal carotid with circle of Willis; 

 ia, inferior alveolar; iv, infraorbital; i, optic chiasma; li, lingual; mm, middle 

 meningeal; ms, muscular; oe, occipital; ol, anterior cerebral; pi, palatine; pa, 

 posterior auricular; s, anterior spinal; th, thyreoid; x, hypophysis; I, 2, 3, 4, 5, 

 and 6, transverse foramina in cervical vertebrae. 



cranial nerve and the sympathetic trunk lie in the same sheath 

 with the carotid (Fig. 72). 



