Arteries of the Neck. 389 



At the jiincticn of the arciis aortae with the aorta thoracalis there is frequentl}' a cou- 

 striction, the isthmus aortae, and, just beyond this, an oblong expansion, the aortic spindle 

 (see Fig. 433). Both formations are especially well marked when the vessel is much curved. 



From the upper wall of the aortic arch go oft': a. anonyma, a. carotis co??imimis 

 sinistra and a. subciavia sinistra. 



A. anonyma (innominate artery) (see Figs. 427 and 429) runs obliipiely in front of 

 the trachi'a from the leit and below to the right and upward, covered in front by the venae 

 anonymae: it divides behind the articulatio sternoclavicularis dextra into the a. carotis corn- 

 munis dextra and the a. subciavia dextra. 



A. carotis communis (common carotid artery) (see also Figs. 435, 441 and 449) 

 runs behind the articulatio sternoclavicularis, at first on the right somewhat further forward, 

 on the lateral surface of the trachea, tlion behind the lobe of the thyreoid gland, in front of the 

 mm. scaleni and longus colli, upward and somewhat backward and divides near the cornu superius 

 of the cartilago thyreoidea into the a. carotis externa and the a. carotis interna. It is ac- 

 companied in front and lateralward by the v. jugularis interna, behind by the n. vagus, and 

 is partially covered by the mm. sternothyreoideus, sternocleidomastoideus and omohyoideus. 



A. carotis externa (external carotid artery) (see also Figs. 438, 439 and 441) 

 passes almost straight upward, partly covered by the venter posterior of the m. digastricus 

 and by the m. stylohyoideus, runs along the posterior margin of the ramus of the lower jaw 

 on its medial surface, surrounded on all sides by the glandula parotis, and divides at the collum 

 mandibulae into its two terminal branches: a. temporalis sitpcrficialis and a. maxillaris interna. 

 It is partly covered by the v. facialis communis and by the n. hypoglossus. Branches: 



1. A. thyreoidea snperior (superior thyreoid artery) (see also Figs. 435, 441 and 

 449) . arises from the antericir wall of the pomt of division , sometimes even somewhat more 

 deeply; runs in a curve forward and downward to the upper end of the lateral lobe of the 

 thyreoid gland, covered partly by the \ enter superior of the ra. omohyoideus. Branches: 



a) Ramus hyoideus upward to the hyoid bone. 



b) Rainus sternocleidomastoideus lateralward and downward to the m. sternocleidomast. 



c) A. laryngea superior perforates the membrana hyothyreoidea , being covered by the 



m. th\Teohyoideus, and anastomoses on the lateral surface of the laryngeal muscles 

 with the a. laryngea inferior (a. thyreoidea inferior) and with a branch of d). 



d) Ramus cricot/iyreoideus runs just in front of the m. cricothyreoideus and the Ug. 



cricothyreoideum medianward: it anastomoses with that of the other side. 



e) and f) Ramus anterior and ra7tiiis posterior, to the anterior and posterior surface of 



the glandula thyreoidea ; both break up into numerous rami ylandulares (to the gland). 



2. A. lingualis (lingual artery) (see also Figs. 435 and 441), goes off, at the level of 

 the gTeater conni of the hyoid bone, from the anterior wall, extends in a curve upward upon 

 the m. constrictor pharyngis raedius, tlien, parallel to and above the hyoid bone, forward upon 

 the m. longitudiualis inferior and the m. genioglossus, covered by the m. hyoglossus. Branches : 



a) Ramus hyoideus downward to the lateral surface of the hyoid bone. 



b) Rami dorsales linyuae, double or single, on the medial surface of the m. hyoglossus, 



upward to the region of the root of the tongue and the tonsil. 



c) A. sublingualis arises at the anterior border of the m. hyoglossus. runs between the 



ra. mylohyoideus and the m. genioglossus below the glandula sublingualis forward, 

 supplies the floor of the mouth and the gums of the anterior teeth; it anastomoses 

 through the m. myloliyoideus with the a. submontalis. 



d) A. profunda linynae {(). T. ranine artery), very tortuous, runs upward and forward 



between the m. longitudiualis inferior and the m. genioglossus ; it anastomoses above 

 the frenulmn linguae with that of the other side. 



3. A. maxillaris externa (external maxillary artery) (0. T. facial artery) (see also 

 Figs. 436 and 441) arises, close above the a. lingualis, from the anterior wall, covered by the 

 venter posterior of the m. digastricus and by the m. stjdohyoideus ; it runs forward in a curve 

 on the medial and upper surface of the glandula submaxillaris, between it and the lower jaw, 

 then bends around the basis mandibulae at the anterior margin of the m. masseter and passes, 

 very tortuous, upon the mm. buccinator and caninus to the side of the nose. In the face it is 

 covered by the platysma, mm. risorius. zj'gomaticus and quadratus labii superioris. Branches : 



a) A. palatina ascendens (0. T. ascending or anterior palatme artery) (see Fig. 441) arises 



near the origin of the vessel (frequently from the a. carotis externa or a. pharyngea 

 ascendens), runs upward upon the m. stylophar^'ngeus, then between this muscle and 

 the m. styloglossus, then upon the m. constrictor pharyngis superior to the medial 

 surface of the m. tensor veli palatini: it supplies the soft palate and the pharynx. 



b) Ramus tonsillaris (see Fig. 441), frequently a branch of a), runs upon the m. con- 



strictor phar\iigis superior to the tonsilla palatina and to the soft palate. 



