THE COMMON CAROTID ARTERIES. 661 



perforating branches which cross the inttrosseous spaces to unite with the dor.sal interoasese; 

 the palmar interossect, which join the superficial interoseese before tlieir division into collateral 

 branches. I^astly, the carpal dorsal arch gives otf the dorml interosseoe, which receive per- 

 forating filaments above and below the metacarpus, and are expended in the articulations and 

 ekin of the lingers. 



Article VIL— Common Carotid Arteries (Figs. 375, 14; 381, 1). 



These two vessels (named from Kapa, the head) ^ arise from the right axillaiy 

 artery, at a short distance from its origin, by a common trunk — the cejihalic 

 artery — which is detached at a very acute angle, and is directed forward Vjeneath 

 the inferior face of the trachea, and above the anterior vena cava, to terminate 

 near the entrance to the chest by a bifurcation that commences the two common 

 carotids —right and left. 



Each of these arteries afterwards ascends in a sheath of connective tissue, 

 along the trachea, at first beneath that tube, then at its side, and finally a little 

 above its lateral plane. Each caiotid airives in this way at the larynx and 

 guttural pouch, where it divides into three branches. 



In its course, this vessel — independently of the connection between it and the 

 trachea — has the following relations : — 



Throughout its entire length, it is accompanied by the cord that results from 

 the union of the pneumogastric nerve with the cervical portion of the sympa- 

 thetic, and by the recurrent nerve ; the latter is placed below or in front of the 

 vessel, from which it is somewhat distant in the lower part of the neck ; the 

 first is situated above or behind the artery, and lies close to it. 



It is also related : behind, in its upper two-thirds, to the longus colli and the 

 rectus capitis auticus major ; outwardly, to the scalenus towards the inferior 

 extremity of the neck, and to the subscapulo-hyoideus, which separates the 

 artery and jugular vein in the middle and upper part of the neck. But near the 

 entrance to the chest these two vessels are in direct relationship — the vein below 

 and the artery above. 



It is also to be noted, that the glands at the entrance of the chest are in 

 contact with the carotids, and that the left artery is related, besides, to the 

 oesophagus. 



Collateral Branches. — The branches furnished by the common carotid 

 on its course are somewhat numerous, but they are of such inconsiderable 

 diameter that their successive emission does not sensibly vary ihe calibre of the 

 vessel from which they emanate ; so that the carotids represent, from their origin 

 to their termination, two somewhat regular cylindrical tubes. These collateral 

 branches are destined either to the mtiscles of the cervical region, or to the 

 oesophagus and trachea. Two of them — the thijro-laryngeal and accessory thyroid 

 arteries — will occupy us in a special manner. 



Thyro-laryngeal Artery (Fig. 381, 14"). — This vessel, which corresponds 

 exactly to the superior thyroid artery of Man,^ arises from the common carotid at 

 a short distance from its termination, a little behind the larynx or above the 

 thyroid body ; it passes on that organ, into which it enters by two principal 

 branches that turn round its superior extremity and anterior border, after sending 

 two branches to the larynx — a superior, also for the pharyngeal walls ; and 



' Baillet has remarked that the two common carotid arteries have not the same calibre In 

 the Horse. 



' We would have given it the same name if we could have found the true representative of 

 the in/erior thyroid artery. 



