634 



CIRCULATORY SYSTEM OF THE DOG 



The external thoracic artery ai-isos outside of the thorax and sends branches 

 to the mammar>' ghmds. 



The common carotid arteries, left and right, arise in that order from the 

 brachiocephalic. In the neck the right one lies on the trachea, the left on the 

 oesophagus. Collateral branches are the posterior thyroid (which may, however, 

 arise from the right or left brachial or the inferior cervical), pharyngeal, thryo- 

 laryngeal, muscular, tracheal and glandular (to the submaxillary gland). Each 

 carotid divides under the wing of the atlas into occipital and internal and ex- 

 ternal carotid liranches. 



The occipital artery is small. It gives off condyloid and posterior meningeal 

 branches, passes up through the notch on the anterior margin of the wing of the 

 atlas, and is distributed to the muscles of this region. Its cerebrospinal branch 



Fig. 486. — Superficial Vessels of Head of Dog. 

 1, Facial artery; 2, inferior labial artery; 3, artery of angle of mouth; 4, superior labial artery; 5, lateral 

 nasal artery; ff, dorsal nasal artery; 7, superficial temporal artery; S, transverse facial artery; 9, anterior auricular 

 artery; iO, zygomatico-orbital artery; 11, satellite vein of 10; i^, ant. auricular vein; iS, superficial temporal 

 vein; 14, internal maxillary vein; IS, post, auricular vein; 16, 17, external jugular vein; 18, external maxillary 

 vein; .?9, ^S, facial vein; ;20, inf. labial vein; .2/, buccinator vein; ^;?, vena reflexa; ^.4, superior labial vein; ^5, 

 vena angularis oculi; ^6, dorsal nasal vein; a, concha; 6, parotid gland; c, submaxillary gland; rf, submaxillary 

 lymph glands; e, mylo-hyoideus; /, digastricus; g, masseter; /(, zygomaticus; i, scutularis; k, temporahs; /, or- 

 bicularis oculi; m, zygomatic arch; n, retractor anguh oris; o. buccinator. (Ellenberger-Baum, Anat. d. Hundes.) 



passes through the intervertebral foramen, and unites in the vertebral canal with 

 its fellow and a branch from the verteliral artery to form the basilar. A retrograde 

 branch anastomoses with the vertebral as in the horse. 



The internal carotid artery, also small, passes to the foramen lacerum posterius, 

 enters the carotid canal and forms a bend before entering the cranium through the 

 carotid foramen. It forms a plexus which is connected by branches with the middle 

 meningeal and ophthalmic arteries. It then perforates the dura mater and enters 

 into the formation of the arterial circle (of Willis). 



The external carotid artery is the direct continuation of the common carotid. 

 It passes along the lateral wall of the pharynx, emerges from beneath the digastricus, 

 and divides into su]ierfi('ial temporal and internal maxillary arteries. It gives off 

 the large flexuous lingual artery which has a course similar to that of the horse. 



