610 THE BLOOD-VASCULAR SYSTEM OF THE OX 



3. The inferior cervical artery corresponds usually to the ascending branch of 

 that vessel in the horso. 



4. The external thoracic artery is large and usually gives off a branch which is 

 equivalent to the descending branch of the inferior cervical artery of the horse. 



THE COMMON CAROTID ARTERY 



The carotid arteries usually arise from a common trunlv about two inches (ca. 

 5 cm.) in length, but in exceptional cases are given off separately from the brachio- 



FiG. 468. — Schema op Chief Arteries op Head of Cow, 

 1, Common carotid artery; 2, thyro-laryngeal; 3, thyroid; 4. laryngeal; 5, pharyngeal; 6. occipital; 7, 

 condyloid; S, middle meningeal; 9, pharyngeal; iO, external maxillary; li, lingual; 7 ;2, sublingual; 75, superior 

 labial; 14, internal maxillary; 16, masseteric; 16, inferior alveolar; 17, buccinator; IS, great palatine; 19. 

 sphenopalatine; ;20, posterior auricular; .27 , superficial temporal ; ;2^. posterior meningeal; .23, anterior auricular; 

 24, artery to matrix of horn; 26, deep temporal: 26, arteries to rete mirabile: 27, frontal: 28, malar; 28', dorsal 

 nasal continuation of malar; 29, infraorbital; 29' , lateral nasal continuation of 29. 



cephalic. Each ]:)ursues a course similar to that of the horse and is accompanied 

 by the small internal jugular vein, l)ut is separated from the external jugular vein 

 by the omo-hyoid and sterno-mastoid muscles. It divides at the digastricus into 

 occipital, external maxillary, and external carotid arteries. In addition to tracheal, 

 oesophageal, and muscular branches, it gives off the thyroid and laryngeal arteries. 

 The thyroid artery (A. thyreoidea cranialis) bends around the anterior end of the 

 thyroid gland, in which it ramifies. The accessory thyroid artery is usually 

 absent. The laryngeal artery may arise with the thyroid. 



