830 



NERVOUS SYSTEM OP THE HORSE 



branches derived from the anterior cervical ganglion. The ganglion gives off two 

 or three filaments which subdivide to form the internal carotid plejnis (Plexus 

 caroticus internus) around the artery of like name. The cavernous plexus (Plexus 

 cavernosus) surrounds the artery within the cavernous sinus and communicates 

 with that of the opposite side. The external carotid plexus (Plexus caroticus 

 externus) is formed around the homonymous artery, and filaments from it go to the 

 vessel and its branches and to the salivary glands. 



2. The cervical part (Pars cervicalis s. sympathici) includes two ganglia and 

 the trunk which connects them. 



The anterior or superior cervical ganglion (G. cervicale craniale) lies on the 

 guttural pouch below the occipito-atlantal articulation (Fig. 562). It is reddish- 

 gray in color, fusiform, and about an inch (ca. 2-3 cm.) in length. It is connected 

 by rami communicantes with the last four cranial and first cervical nerves, sends 

 branches to form the plexuses mentioned above, and contributes to the pharyngeal 

 plexus. 



The cervical trunk of the sympathetic connects the anterior and posterior 



Fig. 660. — Right Cervico-thoracic Ganguon and 

 Related Structures of Horse. 

 G, G', Ganglia; 5, sympathetic trunk; V, vagus; 

 Ji, recurrent nerve; .Y.c, cardiac nerves, C XIII, T.I., 

 rami communicantes from eighth cervical and first thor- 

 acic nerves; A'.^r., nervus transversarius; 7". b., brachio- 

 cephalic trunk; A.d.c.y dorso-cervical artery; A.b.d., 

 right brachial artery; A.c.c, common carotid artery. 



Fig. 661. — Left Cervico-thoracic Ganglion and 

 Related Structures of Horse. 

 G, G', Ganglia; S, sympathetic trunk; V, vagus; 

 R, recurrent nerve; C.VII, C.VIII, T.I, rami com- 

 municantes from last two cervical and first thoracic 

 nerves; N.tr., nervus transversarius ; N.c, cardiac 

 nerves. 



cervical ganglia. On leaving the former it is associated in a common sheath with 

 the vagus along the dorsal face of the common carotid artery. At the root of the 

 neck it separates from the vagus and joins the posterior cervical ganglion. 



The posterior or inferior cervical ganglion (G. cervicale caudale) is situated 

 under cover of the first rib and the insertion of the scalenus (Figs. 660, 661). On 

 the right side it lies upon the longus colli and the trachea, on the left side upon the 

 same muscle and the cesophagus. It is flattened, very irregular and variable in 

 outline, and is blended more or less with the first thoracic ganglion,^ so that the two 

 may be considered together as the ganglion steUatum. This receives at its antero- 

 dorsal angle the nervus transversarius, which accompanies the vertebral artery 

 in the canalis transversarius; it is a trunk formed by the rami communicantes of 

 the cervical nerves except the first and last. Large rami connect with the last 

 cervical and first and second thoracic nerves. Filaments also connect with the 

 vagus. From the ventral part of the ganglion proceed the cardiac nerves now to 

 be described. 



^ In some oases there exists a more or less distinct middle cervical ganglion which receives 

 the filaments from the vagus and is connected with the posterior cervical ganglion by a trunk. It 

 occurs oftenest on the right side and gives off one or two cardiac nerves. 



