Page 25 - My FlipBook

OF THE ARTICULATION OF TIIE LOWER-JAW. 5*
In the head of a young subject which I examined, I found
that the two first Incisor Teeth in the Upper-Jaw had not cut
the Gum ; nor had they any root or fang, excepting so much as
was necessary to fasten them to the Gum, on their upper surface
;
and on examining the Jaw, I found there was no Alveolar Pro-
cess, nor sockets, in that part. What had been the cause of
this, I will not pretend to say : whether it was owing to the
Teeth forming not in the Jaw, but in the Gum ; or to the wasting
of the fangs. The appearance of the Tooth favoured the first
supposition ; for it was not like those, whose fangs are decayed
in young subjects, in order to the shedding of the Teeth ; and
as it did not cut the Gum, it is reasonable to think it never had
any fang. That end from which the fang should have grown,
was formed into two round and smooth points, having each a
small hole leading into the body of the Tooth, which was pretty
well formed.

OF THE ARTICULATION OF THE LOWER-JAW.
Just under the beginning of the Zygomatic Process of each
Temporal Bone, before the external Meatus Auditorius, an ob-
long cavity (o) may be observed; in direction, length, and breadth,
in some measure corresponding with the Condyle of the Lower-
Jaw, (p) Before, and adjoining to this cavity, there is an oblong

(o) [In all Mammals the articular surface for the condyle is either
concave or flat.]
(j>) [It is evident that the description in the text refers only to the
articulating portion of the glenoid cavity, or that anterior to the
Glaserian fissure. The posterior portion of the cavity lodges a process of
the parotid gland, and does not enter into the articulation. In Man, as
in all other Mammalia, the lower jaw articulates with the squamous
element of the temporal bone in them the tympanic element is
;
solely subservient to the organ of hearing. But this is not the case
in the other vertebrate classes. In birds, reptiles, and osseous fishes,
the mandible articulates with bones, which are the homologues of the
i\ oapanic ring in Man. In cartilaginous fishes, the articulating surface
is formed by the pterygoid bone, the homologue of the internal pterygoid
plate in the human subject. In the Lepidosiren, which in other re-
c