636 



BLOOD-VASCTJLAE SYSTEM OF THE HORSE 



laterally to the vagus and recurrent nerves. It is commonly two or three inches 

 (ca. 5-7 cm.) in length, but it may vary between one and eight inches (ca. 2.5- 

 20 cm.).i 



The right common carotid artery (A. carotis communis dextra) passes obliquely 

 from the ventral face of the trachea to its right side and continues in this position, 

 but inclines toward the dorsal surface of the trachea near its termination. It 



Fig. 556. — Vessels and Nerves of Neck oe Hohse. 

 a, Brachiocephalicus; b, stenio-rephalicus; c, omo-hyoideus; d, sterno-thyro-hyoideus; e, trachea; /, position of 

 cariniform cartilage; (7, anterior superficial pectoral muscle; /i, scalenus; i, intertransversales; A:, insertion of serratus 

 cer\'icis; /, remnant of trapezius; rn, rhomboideus; n, splenius; o, complexus; p, g, longissimus capitis et atlantis; p',q', 

 tendons of same; r, longissimus; s, obliquus capitis posterior; t, wing of atlas; w, parotid gland; v, supraspinatus ; w, 

 anterior deep pectoral ; x, spine of scapula; y, prescapular lymph glands; 2, external maxillary vein; ^, 5, jugular vein; 

 4, carotid artery, exposed by drawing jugular vein aside; 5, 6, ascending and descending branches of inferior cervical 

 artery; 7, cephalic vein; 8, branches of deep cervical artery; 9-14^ ventral branches of second to seventh cervical nerves; 

 15, branches of dorsal divisions of cervical nerves. (Ellenberger-Baum, Top. Anat. d. Pferdes.) 



divides at the crico-pharyngeus muscle and under cover of the mandibular gland 

 into external carotid, internal carotid, and occipital arteries.^ It is enclosed in a ' 

 fibrous sheath, and is accompanied dorsally by the vagus and sympathetic nerves, 

 ventrally by the recurrent nerve. In the posterior part of the neck it is in contact 



' In very rare cases there is no truncus bicaroticus. The two carotid arteries then arise 

 separately from the brachiocephahc, the left one first, and the right one an inch or more further 

 forward. 



^ A small nodule is present in the angle of division. This is the carotid body or glomus caro- 

 ticum. 



