(From to chew,) mandibula.
The cheek or the jaw. See Buccae.
Maxilla inferior, mela. The lower jaw is situated at the lower part of the face; divided into the chin, sides, and processes. The chin is the anterior middle part; the sides are continued beyond the chin, till the bone, bending upwards, forms the processes. On the middle part of the chin externally there is a transverse ridge, on each side of which the quad rati, or depressores labii inferiores,and the elevatores Iabii inferiores, hollow out the bone, and are lodged in the furrow. On the internal part of the chin are three protuberances, to the uppermost of which the fraenum linguae is tied. From the middle protuberance the genioglossi arise; and from the lowest the genio hyoidei: below the last the digastric muscles are attached to two sinuosities; and at the lower and anterior external pare of each side of the maxilla inferior there is a small protuberance, whence the depressor labiorum communis proceeds: and nearer the upper edge is a longitudinal ridge, where the buccinator is inserted; inwardly, towards the superior ridge of each side, is a ridge, whence the mylo hyoidei rise. The lower edge of the chin and sides are smooth, and are called the base of the lower jaw, the extremities of which are named the angles: the outer surface of these angles hath several inequalities where the masseter is inserted, and the inner surface where the pterygoideus interims is attached.
The anterior sharp process is called coronoides apo-fihysia maxilla, round which the temporal muscle is inserted; and the posterior process is called condyloid, which is received into the glenoid cavity of the os tem-poris. The upper part, where the teeth are inserted, is called the alveolar process.
The foramina are two on each side, one near the root of the processus internally, where a branch of the fifth pair of nerves with an artery and a vein enters; the other, external, at the edge of the chin, where the nerve and the vessels come out.
Maxilla superior, the upper jaw, is composed of thirteen bones, viz. the ossa nasi, unguis, malarum, maxillaria, palati, spongiosa inferiora, or turbinata infe-riori, and the vomer.
The diseases of the maxilla are chiefly those of the sinuses, and in these worms have been sometimes found; hut they are more commonly receptacles of purulent matter. They are sometimes the seat of fistulous ulcers, occasionally of a destructive fungous or cancer, and often of a caries, which happens in some instances after measles or small pox. Matter is let out by drawing the first or second molar tooth, and we recollect, among Gooch's cases, one in which it was discharged by puncturing the cheek. In the Ephemerides Naturae Curiosorum is an instance of a total separation of the lower jaw which the man survived. See Luxatio and Fractura.