LINGUAL ARTERY. 36 a 



distributes branches to its substance, and communicates freely with the 

 branches of the inferior thpoid artery. 



Branches. — Besides the branclies fumished to the muscles which cover it. and 

 to the thyi'oid body, together with some to the lowest constrictor of the pharynx, 

 the superior thyroid furnishes the following offsets, which have received distinc- 

 tive names : — 



(tf ) The Jiyoid, a small branch, running transversely inwards immediately below 

 the OS hyoides, and assisting to supply the soft parts connected with that bone. 

 This little artery sometimes unites, across the middle line, with its fellow from 

 the opposite side. 



(J)) A xi/jwrjicial descending or sterno-mastoid branch, which passes downwards 

 a short distance over the sheath of the large cei-vical vessels, and ramifies in the 

 sterno-mastoid and the muscles attached to the thyroid cartilage, as well as in 

 the platysma and neighbouring integuments. The position of this branch with 

 respect to the sheath of the carotid artery is the only circumstance which gives 

 it interest. This branch frequently arises directly frona the external carotid. 



{c) The larijnrieal branch, or .superior larynrjcnl arterij. proceeding inwards in 

 company with the superior laryngeal nei-ve. and piercing the thyro-hyoid mem- 

 brane. Before entering the larynx this branch is covered by the thj-ro-hyoid 

 muscle. On reaching the interior of the larynx, it ramifies in the small muscles, 

 the glands, and the mucous membrane of that organ. 



(rZ) The crico-tlnjroid, a small branch, to be noticed on account of its position 

 rather than its size. It crosses the membrane connecting the thjToid and cricoid 

 cartilages, and communicates with a similar branch from the other side : hence 

 it may be a source of hasmorrhage in the operation of larjTigotomy. 



Varieties. — She. — The siiperior th.^nroid artery is frequently much larger, and, 

 on the other hand, it maj' be smaller than usual. In either case the deviation 

 from the accustomed size is accompanied by an opposite alteration in other 

 thyroid arteries. It has been seen extremely small, ending in branches to the 

 sterno-mastoid muscle and the larynx. (See the observations on the inferior 

 thyi'oid artery.) 



Orif/in.^The superior thyroid is often transferred to the upper part of the 

 common carotid artery ; and it has been seen conjoined with the lingual branch, 

 or with that and the facial branch of the external carotid. 



There are sometimes two superior thjToid arteries. 



Srancheii. — The ]njoid branch is frequently very small, or absent. The Iiiri/n- 

 geal branch arises not unfrequently from the external carotid artery, and like- 

 wise, but rarely, from the common carotid. Examples have occun-ed of this 

 branch being of very large size, and terminating in the thyroid body. The 

 laryngeal artery occasionally enters the larynx through a foramen in the thyroid 

 cartilage, and it has likewise been observed to pass inwards below the cartilage. 



2. lingual Artery. — The lingual artery arises from the inner 

 side of the external carotid, between the origins of the superior thyroid 

 and facial arteries. Curving upwards and inwards, it reaches the upper 

 margin of the hyoid bone, behind the tip of its great cornu ; it then 

 passes forwards imder cover of the hyo-glossus muscle, resting at first 

 on the middle constrictor of the pharynx, and afterwards on the 

 genio-hyo-glossus muscle, in contact with which it ascends almost per- 

 pendicularly to reach the under surface of the tongue, and there makes- 

 its final turn forwards to the tip of that organ, receiving the name of 

 ratline artery. 



At the posterior border of the hyo-glossus muscle, the hypoglossal 

 nerve crosses the artery, and passes forwards on a lower level, superficial 

 to the muscle. 



Branches. — (u) The Jn/oid branch rans along the upper border of the hyoid 

 bone, and sujDplies the contiguous muscles and skin. 



