662 THE ARTERIES. 



an inferior, much more considerable, exclusively distributed to the laryngeal 

 apparatus. The latter passes between the cricoid and the posterior border of 

 the thyroid cartilage, on the internal surface of which it sends off several 

 ramuscules, some of which pass forwards, others backwards — the latter spreading 

 over the ventricle of the glottis and the thyro-arytsenoid muscle, to become 

 expended in the arytaenoid muscle. The superior branch for the pharynx, also 

 supplies the crico-arytaenoideus. 



It sometimes happens that the thyro-laryngeal artery is found divided at its 

 origin into two quite distinct branches, each furnishing a laryngeal and a thyroid 

 division, as in Fig. 381, 3.^ 



We have already remarked on the disproportion existing between the con- 

 siderable calibre of the branches sent by this artery to the thyroid body, and the 

 slender volume of that organ ; so that it will at present suffice to remind the 

 student of this peculiarity. 



Accessory Thyroid Artery (Figs. 375, 14' ; 381, 2). — The origin of this 

 vessel precedes that of the first ; it is much smaller, and enters the thyroid body 

 by the posterior or inferior extremity of this glandiform lobe. 



This artery often sends only some excessively fine ramuscules to the thyroid 

 body, and expends itself almost entirely in the cervical muscles.^ 



Terminal Branches. — The three branches which terminate the common 

 carotid are the occipital, and internal and external carotid arteries ; the latter is 

 incomparably larger than the other two, which only appear to be collateral 

 offshoots from the principal vessel. It is these l)ranches which distribute the 

 blood to the various parts of the head. We will devote three special paragraphs 

 to their study ; but their preparation will previously demand some notice. 



Preparation of the arteries of the head. — After carefully removing the skin, dissect the 

 superficial arteries of one side — that is, the external maxillary, maxillo-muscular, tlie temporal 

 trunk, and the posterior auricular arteries — excising the parotid gland to expose the origin of 

 the three last-named vessels. On the opposite side, the deep arteries are prepared, after dis- 

 posing of the branch of the inferior maxilla, as in the preparation of the muscles of the 

 TONGUE ; tlie orbital and zygomatic processes being removed in three sections with the saw, as 

 in Fig. 381, which will serve as a guide in the dissection of all these arteries. 



It is possible to prepare all tlie arteries on one side ; and in order to do this, a commence- 

 ment should be made by dissecting the superficial branches; after which, these are cut in the 

 middle of their course and the first half thrown hack on the parotid. The facial is left intact. 

 The deep arteries are reached by ilividing and disposing of the inferior maxilla, as was directed 

 in the second procedure in preparing the muscles of the tongue and pharynx. 



Occipital Artery (Fig. 381, 6). 



The occipital artery is a slightly flexuous vessel, lying alongside the upper 

 third of the internal carotid. It ascends beneath the transverse process of the 

 atlas, in passing behind the guttural pouch, between the maxillary gland and 

 the straight anterior muscles of the head. It then insinuates itself between the 

 rectus capitis lateralis and the inferior arch of the above-named vertebra, to pass 

 through its anterior foramen, and terminate by two branches, after coursing 

 along the short fissure that unites this foramen with the superior foramen. In 



' It was doubtless a case of this kind that Rigot had before liim when he described the 

 above vessel, and made two arteries of it — tlie thijroid and laryngeal. But, we repeat, this is 

 only an exceptional instance, and does not authorize its being supposed to be the rule, and 

 cause the creation of a distinct thyroid an<l laryngeal artery; since each branch of the vessel 

 is distributed to tlie larynx and thyroid boily at the same time. 



• We regard it as the analogue of the middle thyroid of Man. 



