Branches.—Having given a few inconsi derable twigs to the middle constrictor, stylo glossus, digastric, and stylo-hyoid muscles, and to the sublingual gland, &c.; the lingual artery sends off the following branches. a, The hyoidean branch, arising at the external edge of the hyoglossus muscle, passes be tween the genio-hyoideus and genio-glossus, and coming forward in the mesial line, de scends over the front of the body of the os hyoides, and anastomoses with the hyoidean branch of the thyroid artery, giving branches to the muscles, in the vicinity of which it passes and to the integuments. 1), The dorsalis unglue, arising under cover of the hyoglossus, passes upwards and outwards, crossing the stylo-glossus and distributes its branches over the posterior part of the dorsum of the tongue, the tonsils, velum palati, and epiglottis, where it anastomoses with the laryngeal branch of the superior thyroid. At the internal edge of the hyoglossus the lingual artery divides into the sublingual and ranine. c, The sub lingual branch passes forwards between the mylo-hyoid and genio-glossus muscles and above the sublingual gland, to which it is principally distributed, as well as to the muscles of the tongue and the mucous mem brane of the mouth. Occasionally we find the place of the sublingual artery supplied by the submental, a branch of the facial. d, The ranine artery, which is the continuation of the trunk of the lingual, passes forward between the genio-glossus and lingualis, and running along the under surface of the tongue by the side of the attachment of the frwnum, sends nu merous branches into the substance of that organ, and ends by anastomosing with the ranine of the opposite side. It is this artery which is endangered if the scissors be directed too much upwards in dividing the frwnum lingum in children.
3. The labial artery, called also facial or external maxillary, (a. facialis v. maxillaris externa,) varies very much in its origin, size, and the extent of its distribution. It is usually the largest of the three anterior branches of the external carotid, and supplies the whole of the anterior part of the face ; sometimes, however, it only extends as far as the angle of the mouth, beyond which its place is supplied by the temporal artery. There is, perhaps, no other artery which presents so many varieties, even on opposite sides of the body in the same subject. From its origin it proceeds, in a tortuous course, inwards and forwards, towards the internal part of the angle of the lower jaw, covered by the hypo glossal nerve, the digastric and stylo-liyoid muscles : it then passes between the lower jaw and submaxillary gland, lodged in a groove in that gland ; after which it turns over the inferior border of the lower jaw, and arrives on the external surface of that bone a little in front of the anterior edge of the masseter muscle : from this it ascends tor tuously towards the commissure of the lips, covered by the skin and the platysma ; thence passing upwards and inwards under the zygo matic muscles, and over the buccinator and levator anguli oris, it continues to ascend in the groove between the cheek and the upper lip and by the side of the nose, to the internal canthus of the eye, where, very much nished in size, it terminates by anastomosing with the nasal branch of the ophthalmic artery.
Branches.— The branches of the labial artery are very numerous. a, The inferior palatine, which arises from the labial close to its origin; this vessel sometimes comes from the trunk of the carotid itself, it passes upwards between the stylo-pharyngeus and stylo-glossus, to which it gives branches : it then attaches itself to the superior and lateral part of the pharynx, supplying this region, the tongue, and the tonsil. Having reached the velum palati, it
divides into many branches, which are dis tributed to the muscles, mucous membrane, and glands of that organ, and to the Eustachian tube. These branches anastomose with the superior palatine branch of the internal max illary. The tonsillitic artery, (arteria tonsil laris of Soemmerring,) enumerated as a dis tinct branch of the labial by Professor Harrison, is, more properly speaking, a branch of the inferior palatine.
In passing through the sub-maxillary gland, the labial artery gives off several branches to this gland, the internal pterygoid muscle, and the mucous membrane of the mouth : as it is about to turn over the side of the lower jaw, there arises from it a branch of more considerable size, namely, b, the submental branch. This artery passes forwards beneath the base of the lower jaw, covered by the platysma and anterior belly of the digastric, between which and the mylo-hyoideus it takes its course towards the symphysis of the chin, distributing branches to supply the muscles and integuments in this region and to anasto mose with the sublingual; some of its branches mount over the chin and communicate with the arteries of the lower lip : the subrnental artery sometimes furnishes the sublingual, and at other times it is given off by this latter.
From the inferior border of the lower jaw to the commissure of the lips, the labial gives several branches, some of which are anterior and some posterior : the posterior are com paratively insignificant branches distributed to the masseter, platysma, buccinator, parotid gland and duct, the cellular tissue and in teguments of the cheek, which communicate with branches of the transverse facial. Besides smaller branches given off anteriorly to the lips, there are two considerable branches and one of lesser size, which require a more par ticular description ; viz. c, the inferior labial coronary arises about niidway between the commissure of the lips and the base of the lower jaw, it passes under the triangularis oris muscle, to which, as well as to the quadratus, levator labii inferioris, and mucous membrane of the mouth, it gives numerous branches and anastomoses with its congener, and the mental branch of the inferior dental. This artery is sometimes smaller on one side than on the other; it is sometimes absent on one side, when its place is supplied by the artery of the opposite side ; sometimes it arises from the superior labial coronary ; sometimes it is double. After having given off this branch, the facial artery continues its course upwards and inwards, and, opposite the commissure of the lips, gives off' d, the superior labial coronary artery. This vessel passes inwards among the fibres of the orbicularis oris, runs above the free border of the upper lip nearer to its mucous membrane than to its cutaneous surface, gives branches to the various parts composing the upper lip, and meets the co ronary of the opposite side, with which it very freely anastomoses. The superior labial coronary always sends off from the place where it anastomoses with that of the opposite side a branch, which ascends towards the septum of the nose, and which is called the artery of the septum of the nose, (arteria septi nasi.) The place of this artery is some times occupied by two or more branches ; it divides, near the septum of the nose, into at least two branches, which pass, one on either side, along the inferior border of the septum to the extremity of the nose, where it anasto moses with bmnches of the lateral nasal : sometimes the superior coronary gives off a branch (ramus pinnalis), as it passes the ala of the nose, to which, and the external part of the nostril, it is distributed.