The teeth in man and the anthropoid apes : being a review of the various publications on the subject by Professor Owen, F.R.S. and an essay on the teeth in the varieties of man / by Francis C. Webb.

  • Webb, Francis Cornelius.
Date:
[between 1860 and 1869?]
Catalogue details

Licence: Public Domain Mark

Credit: The teeth in man and the anthropoid apes : being a review of the various publications on the subject by Professor Owen, F.R.S. and an essay on the teeth in the varieties of man / by Francis C. Webb. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

    19/66 (page 15)
    come into place, and to tlie uses to wliicli they are ordained, •\ve shall tinil that new distinctions between Imnian structure and that of the highest Quadruniana ari'est attention at every step of the process ; and moreover, tliat the separation of which these distinctions are indicative cannot, by any fair process of philosophic reasoning, be reduced to mere altera- tion ascribable to the effect of ailventitious influences. The lower jaw (mandibula) in Man and the Quadrumana consists of two lateral symmetrical parts, joined anteriorly in the mesian line. Separate at first, anchylosis takes place between the two lateral portions at an early period. In the human subject, their union is perfected during the second year after birth. Each half consists of two rami, known from their direction as horizontal and vertical. By their union, the two horizontal rami form the body of the bone ; the line of junction is termed the symphysis. The alveoli of the lower dental series occupy the up]:)er border of the hori- zontal ramus. The vertical ramus projects upwards from the hinder extremity of the horizontal; the junction of its pos- terior border with the inferior boundary of the horizontal constituting the angle of the jaw. The anterior border of the vertical or ascending ramus terminates above in a process, the coronoid, into which the crotaphite or temporal muscle is inserted. The upper border of the ramus is hol- lowed into a concavity between the coronoid and the articu- lating process or condyle, the latter surmounting the posterior border, and terminating the superior concave margin of the asconding portion of the bone. Such are the general features; we will now proceed to note and compare the peculiarities of the mandible in each of the subjects selected for review. In Man, the lower jaw is distinguished by the shape of the body, or that portion formed by the two horizontal rami; it is convex in its general outline, which resembles that of a horse-shoe. The horizontal rami are short, and the antero- posterior measurement of the entire jaw is small when con- sidered in relation to the space wliich separates the two condyles, and the corresponding proportions in the Quadru- mana. The alveolar border describes a regular parabolic or elliptic curve; the dental sockets are separated by thin osseous plates, and progressively increase in size from the incisor teeth to the molars ; there is no diastema or vacant space to interrupt the series. The union of the lateral halves is marked externally by a projecting ridge, which terminates below in a jutting horizontal process or promontoiy, the chin.