806 



NERVOUS SYSTEM OP THE HORSE 



The left vagus nerve (Fig. 553) enters the thorax on the lateral or the ventral 

 face of the oesophagus, crosses obliquely under the left brachial artery, and passes 

 back on the lateral surface of that vessel in company with a large cardiac nerve.^ 

 Separating from the latter, the vagus continues backward on the left face of the 



Lig. nuchm 

 Splenitis 



Nuchal fat 



Branch of occipital artery 

 Complexus 



Co?nplexus tendon 



Rectus capitis 

 dorsalis minor 

 Rectus capitis 

 dorsalis major 



Spinal 



accessory 



nerve 



(dorsal 



branch) 



Brack io- 



cephalicub 



Vagus 



Sympathetic 

 Carotid artery , 



Ant. certricnl 

 lymph gland 



Thyroid gland 



External ma 

 illary re 



Slerno- 

 Omo-hyoideus and 



Spinal accessory 

 nerve (dorsal 

 branch) 

 Rectus capitis 

 ventralis major 



Jugular vein 



Thyro-laryngeal 

 artery 



Anterior cervical 

 lymph glands 



Fig. 649. — Crosb-section of Neck of Horse, Passing through Posterior Part of Atlas. 



The head and neck were extended. 1, Dorsal arch of atlas; S, dens of axis; 3, ligament of dens; 4i vertebral 



sinuses; 5, dura mater; 6, spinal cord; 7, vertebral artery: S, wing of atlas; 9, atlanto-axial joint cavity; 10, 



oesophagus; 11, 11, recurrent nerves; 12, 12, ventral branches of spinal accessory nerves. By an oversight the obUquus 



cap. post, {above wing of atlas) is unmarked; also the parotid gland between the jugular and external maxillary vein. 



aorta, inclines to the upper surface of the left bronchus, and divides into dorsal and 

 ventral branches. 



The dorsal and ventral branches unite with the corresponding branches of the 

 opposite nerve, thus forming dorsal and ventral cesophageal trunks (Truncus 



1 In some cases the left vagus passes back below the junction of the jugular veins and the 

 termination of the left brachial vein. It then runs backward and somewhat dorsally across the 

 left face of the anterior vena cava to reach its usual position. 



