Buckmaster's Elements of animal physiology / by John Angell.

  • Angell, John
Date:
1866
Catalogue details

Licence: Public Domain Mark

Credit: Buckmaster's Elements of animal physiology / by John Angell. Source: Wellcome Collection.

    280/384 (page 268)
    Sutures (from L., stio, I sew).—The wall-bones of the adult skull are immoveably fixed to each other by seri-ated or rather dove-tailed edges, the teeth of one bone fitting into corresponding indentations in its adjacent bone. These joints have, as shown in the diagram, a sewed or seam-like appearance, and have therefore been termed sutures. The advantages resulting from the skull’s being fonried of several separate bones are—i, the bones grow from their edges, and are thus enabled to adapt themselves to the growth of the brain, becoming united when the brain has attained its full growth ; 2, an injury received by one bone is less likely to extend to the surrounding parts than it would be did the whole skull consist of one undivided bone ; just as the injury done to a window consisting of many small panes is more likely to be confined to a small surface than in the case of another window of similar size consisting of but one large pane of glass only. The wings of the sphenoid bone at the base of the skull overlap the side wall-bones of the skull, and tend to hold them together like the Ijeams of a roof. When the edges really dovetail together, as the sides of a drawer are fastened by a cabinet-maker, they form true sutures ; but when the edges simply overlap each other like fish-scales, they are termed squamous sutures, as in the case of the temporal bones. The Orbits, bounded by the orbital plates, are deep, conical, hollow cavities or sockets, situated between the forehead and the cheeks. They lodge and protect the eyes, the muscles of the eyeball, the lachrymal glands, situated a little above the outer angles of the eyes, and the cushions of soft fat in which the eyes are packed to preserve them from injuiy. The opening at the back of the orbits is termed the optic foramen; it gives passage to the optic nerve. At the inner angles of the eyes are two openings, one on each side, into the nose. These are termed the lachryjtial grooves; they lodge the lachrymal sacs which pass the tears into the nose. Bones of the Face.—There are fourteen bones in the face, viz.,— Two malar or cheek-bones; two upper maxillary or jaw-bones, each bone containing eight teeth; one lower maxillary, or jaw-bone, containing sixteen teeth ; two lachrymal bones ; two spongy bones ; two tiasal bones, forming the bridge of the nose ; one vomer or ploughshare bone, which divides the nose into two cavities; and the two palate bones, forming the roofoi the back of the mouth.