THE COMMON CAROTID ARTERY 



543 



1. Muscular branches 



lares) of variable siz(\ \\] 



The left common carotid artery differs from the right one in that it is related 

 deeply to the O'sophagus, which separates 

 it from the trachea in the greater part of 

 its course. • 



The collateral branches of the conmion 

 carotids iivv in the main small. They com- 

 prise : 



(Kami miiscu- 

 lich go to the 

 ventral muscles of the neck and the skin. 



2. (Esophageal and tracheal branches 

 (Rami ce.sophagei ct tracheales). Small 

 twigs go to the cervical lymph glands also. 



3. The parotid artery. This comes off 

 near the termination and enters the ventral 

 part of the parotid gland. It also supplies 

 the subparotid lymph glands, and sometimes 

 sends a branch to the submaxillary gland. 

 It is inconstant. 



4. The thyro-laryngeal artery (A. thy- 

 reoidea cranialis). This, the largest col- 

 lateral branch of the carotid, arises from 

 the latter two or three inches before it 

 divides. It curves over the anterior end 

 of the thyroid gland, into which it sends 

 several branches. It gi\es off a laryngeal 

 branch (.\. laryngea), which sends twigs to 

 the external nuiscles of the larynx and the 

 constrictors of the pharynx, passes l)etween 

 the cricoid and thyroid cartilages, and sup- 

 plies the internal muscles and the nmcous 

 membrane of the larynx. A small pharj'n- 

 geal branch (A. pharyngea ascendens) runs 

 upward and forward to the crico-pharyn- 

 geus, and supi)lies twigs to the posterior 

 part of the pharynx and the origin of the 

 oe.sophagus. Small innominate twigs are 

 given off to the trachea, the oesophagus, 

 and the sterno-thyro-hyoideus and omo- 

 hyoideus muscles. 



In some cases the thyroid and laryngeal 

 arteries arise from the carotitl separately or by 

 a short common stem. A laryngeal branch is 

 often detached from the carotid in front of the 

 thyro-laryngeal and enters the larynx w\\h. the 

 superior laryngeal nerve. The pharyngeal branch 

 frequently comes directly from the carotid. 



Fig. 432. — Cross-section of Neck of Horse, 



l'.\SSI.NG THROUGH FiFTH CeRVICAL A'eR- 



TEBR.\; A.nterior View. 



a, Branches of cervical nerves; a', nuchal 

 fat; b, intertransversaiis muscle; c, longi.ssinius 

 muscle; d, vertebral artery; e, vertebral vein; /, 

 vertebral uerve; a, spinal acce.ssory nerve (upper 

 division); h, recurrent ner\'e; i, vago-sympa- 

 thetic trunk; k, tracheal lymph duct; 1, body of 

 fifth cervical vertebra; /', transverse process of 

 same; m, carotid artery; n, jugular vein; o, 

 sv:perior cervical artery; o', satellite vein of o; 

 p, spinal cord; q, dura mater; r, spinal vein; s, 

 ligamentum nuchse; t, rhomboideus muscle; 

 11, splenius; v, complexus; w, multifidus; x, 

 serratus cervicis; y, mastoido-humeralis; z, 

 sterno-cephalicus; /, rectus capitis ant. major; 

 2, omo-hyoideus; 3, panniculus; 4, sterno- 

 thyro-hyoideus; 5, longus colli; 6, 7, trachelo- 

 mastoiileus; 8, trapezius; 9, spinalis; 10, 

 oesophagus; //, trachea, with cartilaginous 

 ring (//'), mucous membrane (11"), and mus- 

 cular layer (W"). (After Ellenberger, in Leiser- 

 ing's .\tlas.) 



5. The accessory thyroid artery (A. 

 thyreoidea caudalis) is an inconstant vessel 

 which arises from the carotid at a vari- 

 able distance behind the thyro-laryngeal — 

 sometimes from the latter or from the paro- 

 tid artery. It sends branches into the posterior part of the thyroid gland and 

 detaches small tracheal and muscular twigs. In some cases it is distributed 

 chiefly or entirely to the adjacent muscles. 



