encompassed on every side with Bones.
III. Besides, its strait coarticu∣lation, it has many strong Muscles which keep it in its place, and draw it upwards: and it has two heads, which are not so apt to slip out as one is.
IV. And on each side it has two Processes in its hinder part, the former of which drawn forwards, being broad and thin, ends in a point: but the latter is carried backwards, and makes a long and transverse head: the for∣mer is inserted into the Os Ju∣gale, but the latter is fixed to the second Sinus, which is made in the Temple-bone.
V. The Jaw-bone (except in young Children) can scarcely be dislocated any other way than for∣wards; nor can it ever go out of Joint, unless its acute Pro∣cess slips under the Os Jugale, and so can't get back again.
VI. From which it is manifest, that it cannot be luxated to the hinder part; because the Teat-like Processes of the Os Temporis do hinder it: nor can it be luxated to the Right Hand (especially in those of ripe Age) because the left head of the Jaw hinders it: nor to the Left Hand, be∣cause the head of the Jaw, on the right side hinders it.
VII. Nor can it be luxated up∣wards, except in a Distortion of the Mouth; nor yet downwards, unless the Mouth gape very wide.
VIII. The Cause. It may be from a frequent and constant mo∣tion of the Jaw-bone, both in Mastication or Chawing, and Speaking, whereby the Muscles being tired are debilitated, and so make way for the Luxation thereof.
IX. But the most common Cause, yea, almost the only Cause, says Sennertus, is the too wide opening and gaping of the Mouth, whe∣ther it be by gaping, or striving to take some very great thing between the Teeth.
X. And tho' sometimes it may be luxated from the laxity of the Ligaments; yet it is seldom cau∣sed from a debility of the Muscles; because that from both Processes of the lower Jaw, arise strong and nervous Tendons, with which the Muscles Crotaphitae and Masseteres are infolded.
XI. The Signs, It is known by the nether Jaw sticking out foremost, and the Process sticking out by the said Jaw; as also, be∣cause the Mouth continues al∣ways open, and the Spittle comes forth involuntarily.
XII. For if the Process resem∣bling a Beak or Bill, falls out of the Os Jugale, it follows, that it must also hang forth, which in one that is not very Fat, is known both by sight and touch.
XIII. If the Dislocation is but on one side of the Face, it stands awry, and the Chin is turned to∣wards the hurt side, having a prominency withal: the Teeth stand not directly under one another, nor can they be brought together, for which reason the Mouth remains open.
XIV. If it is dislocated on both sides of the Face, then does it fall forwards, the Mouth stands open, both the Apophyses are