CAROTID ARTERY. 



485 



that part; but in passing through the gland 

 the artery becomes more superficial as it ascends 

 and is covered only by a very thin layer of the 

 glandular substance at the place where it ter- 

 minates. The branches of the portio dura 

 forming the pes anserinus cross the course of 

 the carotid in the substance of the gland, being 

 superficial to it and separated from it by the 

 posterior facial vein and part of the glandular 

 substance. 



Branches of the external carotid* The ex- 

 ternal carotid gives off eight principal branches; 

 three anteriorly, the superior thyroid, the lin- 

 gual, and the labial or facial; two posteriorly, 

 the occipital and posterior aural ; one internally, 

 the ascending pharyngeal ; and two superiorly, 

 the superficial temporal and internal maxillary, 

 besides several smaller branches, the number 

 and origins of which are subject to great 

 irregularity, and which are distributed to the 

 sterno-mastoid muscle, the superior cervical 

 ganglion of the sympathetic nerve, the digastric, 

 stylo-hyoid, stylo-pharyngeus, and stylo-glos- 

 sus muscles, &c., to the parotid gland, the 

 external ear, and to the integuments. 



ANTERIOR BRANCHES. 1st. The superior 

 thyroid artery (A. thyroidea superior) gene- 

 rally arises opposite the cornu of the os hyoides 

 a few lines above the bifurcation of the primi- 

 tive carotid ; in some rare cases it comes from 

 the trunk of the primitive carotid : it has been 

 also seen to arise from the*lingual. It takes a 

 tortuous course downwards and forwards, and 

 passing under the omo-hyoid, sterno-thyroid, 

 and sterno-hyoid muscles, arrives at the supe- 

 rior and external part of the thyroid body to 

 which it is chiefly distributed: at first it is 

 superficial, being covered by the integuments, 

 platysma, cervical fascia, some lymphatic glands 

 and small veins coming from the superior part 

 of the larynx to join the internal jugular; it is 

 also crossed by the branch of the nervus de- 

 scendens noni which is sent to the superior 

 belly of the omo-hyoid muscle, and the supe- 

 rior laryngeal and several filaments from the 

 sympathetic nerves to the larynx, &c. lie be- 

 neath it. In its course the superior thyroid 

 artery, besides furnishing a variable number of 

 smaller branches, to the muscles and other 

 parts in its vicinity, generally gives off the 

 three following: a. The hyoidean branch, which 

 runs along the inferior border of the os hyoides 

 between the hyo-thyroid muscle and the mem- 

 brane of the same name, to both which it gives 

 branches; it inosculates with the corresponding 

 artery of the opposite side in the mesial line, 

 and with the lingual by a twig which passes up 

 on the front of the body of the os hyoides. 

 The hyoidean branch is often absent. b. The 

 superficial branch passes downwards and out- 

 vards over the sheath of the carotid artery to 

 the sterno-mastoid muscle, to which and the 

 neighbouring lymphatic glands and integu- 

 ments it is finally distributed, anastomosing 



' In the arrangement of the branches of the 

 external carotid artery the writer follows that of 

 Meckel. See his Anatomic Descriptive, &c. trans- 

 lated into French by Breschet and Jourdan. 



in the substance of the sterno-mastoid with 

 branches coming from the occipital above and 

 others from the thyroid axis inferiorly. c. The 

 laryngeal often arising from the external carotid, 

 an occurrence which, according to Meckel, 

 takes place in one case in eight, passes into 

 the larynx through the hyo-thyroid membrane, 

 sometimes through a hole in the thyroid carti- 

 lage; it usually accompanies the superior 

 laryngeal nerve : its branches are lost in the 

 internal muscles and mucous membrane of the 

 larynx and the epiglottis. Before it enters the 

 larynx it gives branches, some of which ascend 

 to anastomose with the hyoidean, others de- 

 scend to the thyroid body ; one of these latter 

 is remarkable for running across the front of 

 the crico-thyroid membrane to anastomose with 

 a similar branch from the opposite side; it 

 generally lies in the situation in which laryn- 

 gotomy is performed. Having given off the 

 above-mentioned branches, and arrived at the 

 superior extremity of the thyroid body, the 

 thyroid artery divides into two branches, one 

 of which descends along its external edge, 

 sending off numerous branches which are lost 

 in its substance, anastomosing freely with the 

 inferior thyroid, the other branch descends 

 coursing along the superior border of that body 

 on which it expends its branches, and arriving 

 at the mesial line below the cricoid cartilage, 

 anastomoses with the corresponding artery from 

 the opposite side : occasionally this brai ch 

 supplies the small artery which crosses the 

 crico-thyroid membrane. 



2. The Lingual Artery (A. lingualis) arises 

 after the thyroid, and sometimes, but rarely, 

 from a common trunk with the thyroid, corner 

 at other times and not unfrequently from the 

 facial. This artery forms in its course a con- 

 siderable curve, the convexity of which is 

 upwards ; it passes forwards and inwards above 

 the cornu of the os hyoides, between the mid- 

 dle constrictor of the pharynx and hyo-glossus, 

 and mounts up towards the base of the tongue, 

 between the hyo-glossus and sublingual gland 

 which lie to its outer side, and the genio-glossus 

 which is internal to it ; then taking a horizontal 

 direction, it passes forwards under the name of 

 ranine artery, in company with the hypo-glossal 

 nerve, coursing between the genio-glossus and 

 lingualis muscles, as far as the point of the 

 tongue where it anastomoses with its fellow of 

 the opposite side. After its origin and before 

 it passes under the posterior edge of the hyo- 

 glossus muscle, this artery runs superficially be- 

 neath the common coverings of the neck, lying- 

 on the middle constrictor of the pharynx above 

 the cornu of the os hyoides; superior to it lie 

 the tendon of the digastric muscle, the stylo- 

 hyoid muscle and the hypo-glossal nerve, 

 which after sending a filament across it to the 

 hyo-thyroid muscle, continues its course for- 

 wards on the cutaneous surface of the hyo- 

 glossus muscle which separates the lingual 

 nerve and artery in this part of their course. 



Branches. Having given a few inconsi- 

 derable twigs to the middle constrictor, stylo- 

 glossus, digastric, and stylo-hyoid muscles, 

 and to the sublingual gland, &c.; the lingual 



