688 



NERVOUS SYSTEM OF THE HORSE 



internal carotid artery and crosses the inner face of the origin of the occipital 

 artery. Here it is joined by the cervical trunk of the sympathetic, and the two 

 nerves continue along the dorsal aspect of the common carotid artery in a common 

 sheath (Fig. 433). At the root of the neck the vagus separates from the sym- 



Lig. nucha: 

 Splenitis 



Nuchal fat 



Branch of occipital artery 

 Complexus 



Complexus tendon 

 Intertransversalis 



Rectus capitis 

 posterior major 



Spinal 



accessory 



nerve 



(dorsal 



branch) 



Mastoido- 



hunieralis 



Vagus 



Sympathetic 

 Carotid artery 



Ant. cervical 

 lymph gland 



Thyroid gland 



External max- 

 illary vein 



Sterno-ccphalicus 

 Omo-hyoideus and sterno-hyoideus 



Spinal accessory 

 ^ nerve {dorsal 



branch) 

 Rectus capitis ante- 

 rior major 



Jugular vein 



Til yro-laryn gea I 

 artery 



Anterior cervical 

 lymph glands 



Tltyroid gland 

 Sterno-thyroideus 



Fig. 517. — Cross-section of Neck of Horse, Passing through Posterior Part of Atlas. 

 The head and neck were extended. 1, Dorsal arch of atlas; 2, odontoid process; .3, odontoid ligament; 

 4, vertebral sinuses; 6, dura mater; 6, spinal cord; 7. vertebral artery; 8, wing of atlas; 9, atlanto-axial joint 

 cavity; iO, aisojjhagus; ii, //, recurrent nerves; 12, 12, ventral branches of spinal accessory nerves. By an 

 oversight the obliquus cap. post, (above wing of atlas) is unmarked, 



pathetic, and from this point backward the relations of the right and left vagi differ 

 somewhat and must l)e described separately. 



The right vagus (Fig. 429) enters the thorax in the angle of divergence of the 

 right brachial artery and the truncus bicaroticus. It then passes backward and 

 slightly upward, crossing obliquely the outer surface of the brachiocephalic artery 

 and the right face of the trachea. Reaching the dorsal surface of the latter near 

 the bifurcation, it divides into dorsal and ventral branches. 



