BRANCHES OF THE LINGUAL ARTERY 539 



thyreo-hyoid muscle, and, perforating the thjTeo-hyoid membrane along with the internal 

 branch of the superior laryngeal nerve, supplies the intrinsic muscles and mucous lining of the 

 larynx. Its further distribution within the larynx is given with the description of that organ. 

 This branch sometimes arises from the external carotid direct. It may enter the larynx by 

 passing through a foramen in the thyreoid cartilage. 



(4) The crico-thyreoid [ramus cricothyreoideus] passes across the crico-thyreoid membrane 

 immediately beneath the lower border of the thyreoid cartilage. It anastomoses with its 

 fellow of the opposite side, and usually sends a small branch through the membrane into the 

 interior of the larynx. Occasionally a considerable twig descends over the cricoid cartilage 

 to enter the isthmus of the thyreoid gland. The crico-thyreoid has, however, frequently been 

 seen of comparatively large size — once as large as the radial, and crossing the membrane 

 obliquely. In order to avoid injuring the crico-thjTeoid artery in the operation of laryngot- 

 omy, it is usual, if the operation has to be done in a hurry, to make the incision through the 

 crico-thyreoid membrane in a transverse du'ection, and as near to the cricoid cartilage as possible. 



(5) The anterior branch [ramus anterior] is the terminal branch supplying the isthmus and 

 the neighbouring part of the lateral lobe of the thyreoid gland. 



(6) The posterior branch [ramus posterior], the other terminal, supphes the posterior part 

 of the lateral lobe, and sends branches to the inferior constrictor of the pharynx and to the 

 oesophagus. It anastomoses wath the ascending branches of the inferior thyi-eoid artery. 



(7) The glandular branches [rami glandulares] are the ultimate twigs, arising from the ante- 

 rior and posterior terminal branches, for the supply of the th>Teoid gland. 



3. THE LINGUAL ARTERY 



The lingual artery [a. lingualis] (fig. 448) arises from the front of the external 

 carotid, between the superior thyreoid and external maxillary (facial) arteries, 

 often as a common trunk with the latter vessel, and nearly opposite or a little 

 below the greater cornu of the hyoid bone. It may, for purposes of description, 

 be divided into three portions: the first, or oblique, extends from its origin to the 

 posterior edge of the hyo-glossus muscle; the second, or horizontal, lies beneath 

 the hyo-glossus; the third, or ascending, beneath the tongue. The first or 

 oblique portion is situated in the superior carotid triangle, and is superficial, being 

 covered merely by the integument, platysma, and deep fascia. Here it lies on 

 the middle constrictor muscle and superior laryngeal nerve. After ascending a 

 short distance, it curves downward and forward beneath the hypoglossal nerve, 

 and, in the second part of its course, runs horizontally along the upper border of 

 the hyoid bone, beneath the hyo-glossus, by which it is separated from the 

 hypoglossal nerve and its vena comitans, and the posterior belly of the digastric 

 and the stylo-hyoid muscles. In this part of its course it lies successively on the 

 middle constrictor of the pharynx and the genio-glossus muscle, and crosses a 

 small triangular space known as 'Lesser's triangle,' the sides of which are formed 

 by the tendons of the digastric, the base by the hypoglossal nerve, and the floor 

 by the hyo-glossus muscle, in which situation it is usually tied. In the third 

 part of its course it ascends tortuously, usually beneath the anterior margin of the 

 hyo-glossus, to the under surface of the tongue, and is thence continued to the 

 tip of that structure lying between the lingualis and the genio-glossus muscles. 

 From the anterior edge of the hyo-glossus to its termination it is only covered by 

 the mucous membrane of the under surface of the tongue. This part of the 

 vessel is sometimes called the ranine artery. The lingual arterj^ is accompanied 

 by small venae comitantes. 



Branches of the Lingual Artery 



The named branches of the lingual artery are: — (1) The hyoid; (2) the dorsal 

 lingual; (3) the subhngual; and (4) the deep lingual (ranine). 



(1) The hyoid branch [ramus hyoideus] (fig. 448) is a small vessel which arises from the first 

 part of the lingual, and courses along the upper border of the hyoid bone, superficial to the hyo- 

 glossus, but beneath the insertion of the posterior belly of the digastric and the stylo-hyoid. 

 It anastomoses with its fellow of the opposite side, and with the hyoid branch of the superior 

 thyreoid artery, and supphes the contiguous muscles. 



(2) The dorsalis linguae (fig. 448) arises from the second portion of the lingual artery, 

 usually under cover of the posterior edge of the hyo-glossus muscle. It ascends to the back of 

 the dorsum of the tongue, and, dividing into branches, supplies the mucous membrane on each 

 side of the V formed by the vallate papillae. It also supplies the pillars of the fauces and the 

 tonsil, where it anastomoses with the other faucial and tonsillar arteries. Instead of a single 

 artery, as above described, there may be several small vessels running directly to the parts 

 mentioned. The artery anastomoses in the mucous membrane by very small branches with the 



