348 EXTERNAL CAROTID ARTERY. 



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. 



(b) A superficial descending branch, which passes downwards a short distance over 

 the sheath of the large cervical vessels, and ramifies in the sterno-mastoid and the 

 muscles attached to the thyroid cartilage, as well as in the platysma and neighbour- 

 ing integuments. The position of this branch with respect to the sheath of the 

 carotid artery is the only circumstance which gives it interest. 



(c) The laryngeal branch, or superior laryngeal artery, proceeding inwards in 

 company with the superior laryngeal nerve, and piercing the thyro-hyoid membrane. 

 Before entering the larynx this branch is covered by the thyro-hyoid muscle. On 

 reaching the interior of the larynx, it ramifies in the small muscles, the glands, and 

 the mucous membrane of that organ. 



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

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

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

 may be a source of hsemorrhage in the operation of laryngotomy. 



PECULIARITIES. Size. The superior thyroid artery is frequently much larger, and, 

 on the other hand, it may 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 thyroid artery.) 



Origin. 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 thyroid arteries. 



Branches. The hyoid branch is frequently very small, or absent. The laryngeal 

 branch arises not unfrequently from the external carotid artery, and likewise, but rarely, 

 from the common carotid. Examples have occurred 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. 



II. 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 under 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 perpendicularly 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 ranine 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 tlie 

 muscle. 



BRANCHES. The branches of the lingual artery are as follows : 



(a) The hyoid branch, running along the upper border of the hyoid bone/ and 

 supplying the contiguous muscles and skin. 



(6) The dorsal artery of the tongue, which is often replaced by several smaller 

 branches. It arises from the deep portion of the lingual artery beneath the hyo- 

 glossus muscle, and ascends to supply the upper part, or dorsum, and the substance 

 of the tongue, ramifying as far back as the epiglottis. 



(c) The sublinguat branch. Taking origin at the anterior margin of the hyo- 

 glossus, this branch turns slightly outwards, under cover of the mylo-hyoid muscle, 

 and between this and the sublingual gland. It supplies the substance of the gland, 

 and gives branches to the mylo-hyoid and other muscles connected with the maxillary 



