892 THE VASCULAE SYSTEM. 







afterwards, for a short distance, by fascia, platysma, and skin, and in the lower part of its 

 extent by the omo-hyoid, the sterno-hyoid, and the sterno-thyreoid muscles, and it is over- 

 lapped by an accompanying vein. 



Branches. (1) In ike carotid triangle (a) A hyoid branch runs along the lower 

 border of the greater cornu of the hyoid bone, under cover of the thyreo-hyoid muscle, to 

 anastomose with its fellow of the opposite side and with the hyoid branch of the lingual 

 artery. It supplies the thyreo-hyoid muscle and membrane. 



(6) The superior laryngeal branch runs forwards, deep to the thyreo-hyoid muscle. 

 It pierces the thyreoid hyo-membrane, in company with the internal laryngeal nerve, 

 supplies the muscles, ligaments, and mucous membrane of the larynx, and anastomoses 

 with its fellow of the opposite side, with branches of the crico-thyreoid artery, and with 

 the terminal branches of the inferior thyreoid artery. 



(c) The sterno-cleido-mastoid branch passes downwards and posteriorly, along the 

 upper border of the anterior belly of the omo-hyoid muscle and across the common carotid 

 artery, to the deep surface of the sterno-mastoid muscle. It anastomoses, in the sterno- 

 mastoid, with branches of the occipital and transverse scapular arteries. 



(2) In the muscular triangle (d) A crico-thyreoid branch passes anteriorly, either 

 superficial or deep to the sterno-thyreoid. It crosses the crico-thyreoid muscle to 

 anastomose, in front of the crico-thyreoid ligament, with its fellow of the opposite side, and, 

 by branches which perforate the crico-thyreoid ligament, with laryngeal branches of the 

 superior and inferior thyreoid arteries. It supplies the adjacent muscles and membrane. 



(e) The terminal branches are anterior, medial, and lateral. 



The anterior terminal branch descends along the anterior border of the corresponding 

 lobe of the thyreoid gland, and the upper border of the thyreoid isthmus, to anastomose 

 with its fellow of the opposite side. The medial branch is the largest ; it is distributed 

 to the medial surface of the lobe. The lateral branch, which ramifies in the lateral 

 surface of the corresponding lobe, is the smallest. All three terminal branches supply 

 glandular branches to the thyreoid gland. They anastomose with each other and with 

 branches from the inferior thyreoid artery. 



(2) Arteria Lingualis. The lingual artery (Figs. 759 and 761) springs from 

 the anterior aspect of the external carotid, opposite the tip of the greater cornu of 

 the hyoid bone, and terminates, as the arteria profunda linguae (O.T. ranine 

 artery), which ends beneath the tip of the tongue, where it anastomoses with its 

 fellow of the opposite side. 



Course. Whilst in the carotid triangle, the first part of the artery forms a loop 

 with the convexity upwards. The second part passes forwards, medial to the hyo- 

 glossus muscle, immediately! above the greater cornu of the hyoid bone, to the anterior 

 border of the hyo-glossus, where it gives off a sublingual branch and becomes the 

 arteria profunda linguae. The profunda linguse artery passes obliquely forwards 

 and upwards, under cover of the anterior border of the hyo-glossus, and then turns 

 directly forwards on the under surface of the tongue to the tip, lying between the 

 inferior lingualis laterally and the genio-glossus medially. 



Relations. The first part of the lingual artery is crossed superficially by the hypo 

 glossal nerve, and is covered by skin, fascia, and the platysma ; it rests medially agains 

 the middle constrictor of the pharynx. The second part is deeper. It lies between th< 

 middle constrictor medially and the hyo-glossus laterally, and is separated by the latte 

 from the hypoglossal nerve, the vena comitans hypoglossi, and the lower part of the sub 

 maxillary gland. The profunda artery of the tongue ascends almost vertically, parallel wit) 

 and medial to the anterior fibres of the hyo-glossus, which are covered by the mylc 

 hyoid, and between the hyoglossus and the genio-glossus ; then it runs forwards betweei 

 the inferior lingualis and the genio-glossus muscles, and is covered, on its lower surface 

 by the mucous membrane of the tongue. Thus, at its termination, near the frenulur 

 linguae, it is comparatively superficial. 



Branches. (a) The ramus hyoideus, a small branch which arises in the caroti 

 triangle and runs along the upper border of the greater cornu of the hyoid bone, 

 anastomoses with its fellow of the opposite side and with the hyoid branch of the superic 

 thyreoid artery. 



(b) The dorsalis linguae is a branch of moderate size which arises from the second pai 

 of the artery and is not uncommonly double. It ascends, between the hyo-glossus and tt 

 genio-glossus, to the dorsum of the tongue, where it branches and anastomoses with i 

 fellow of the opposite side around the foramen caecum. It supplies the posterior part < 



