Human osteology : comprising a description of the bones ; with delineations of the attachments of the muscles, the general and microscopic structure of the bone and its development : to which is added a brief notice of the unity of type in the construction of the vertebrate skeleton / by Luther Holden.

  • Holden, Luther, 1815-1905.
Date:
1857
Catalogue details

Licence: Public Domain Mark

Credit: Human osteology : comprising a description of the bones ; with delineations of the attachments of the muscles, the general and microscopic structure of the bone and its development : to which is added a brief notice of the unity of type in the construction of the vertebrate skeleton / by Luther Holden. Source: Wellcome Collection.

Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.

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    Tceih in the Tlie teeth in the lower jaw correspond^ in lower jaw. number (16) with those in the upper, but differ from them in one or two particulars :—l. The lower molars have only two fangs, an anterior and posterior, while the upper molars hayHKree; 2. When the mouth is closed the teeth of the . lower jaw shut behind those of the upper jaw which forms a larger arch; 3. The external tubercles or cusps of the teeth of the lower jaw fit into the hollows between the external and internal cusps of the teeth of the upper jaw ; by which arrangement we are enabled to use the entire surface of the opposing teeth in grinding the food. When the jaws are closed, each tooth in one jaw is opposed by two in the opposite jaw; one good result of this is, that when we lose a tooth, the corresponding tooth in the other jaw being still more or less opposed, is still of service in mastication. Eamus. The ramus of the jaw mounts up from the body nearly at a right angle. Hence we speak of the angle of the jaw. Excluding its outstanding processes, the ramus is nearly square. Nearly the whole of its outer surface gives insertion to the powerful masseter muscle, which closes W the jaw (fig. 1). On its inner surface (fig. 2) we observe the dental foramen, or the orifice of the canal for the transmission of the inferior dental nerve and artery. The inner margin of the orifice is raised into a short spine for the attachment of the internal lateral ligament of the jaw. Leading down from the orifice is the mylo-hyoid groove, which contains the small nerve of the same name. Below the groove is the rough sur- face for the insertion of the pterygoideus internus muscle. Observe that strong muscles are inserted into the angle of the jaw both on the outer and on the inner surface; and that for this reason fractures through this part of the bone sometimes escape detection. Condyle. The condyle projects from the upper and back part of the ramus in order to form the joiat of the jaw, and it fits into the glenoid cavity of the temporal bone. It is oblong in form, with the long axis directed horizontally inwards and slightly backwards, so that, if prolonged, the axis of u 4