The principles and practice of dentistry : including anatomy, physiology, pathology, therapeutics, dental surgery and mechanism / by Chapin A. Harris.

  • Harris, Chapin A. (Chapin Aaron), 1806-1860.
Date:
1885
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Licence: Public Domain Mark

Credit: The principles and practice of dentistry : including anatomy, physiology, pathology, therapeutics, dental surgery and mechanism / by Chapin A. Harris. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    The superficial fascia lies just beneath the skin, and covers nearly the entire surface of the body. It serves to connect the skin with the deep fascia, and furnishes a nidus for nerves and blood vessels passing to the skin. The deep fascia is composed of fibres arranged in a reticulated manner, forming a dense, inelastic membrane, which invests each muscle in a separate sheath. Sheaths are also formed from it for the vessels and nerves; and it serves also as points of attachment for the muscles. Each striped muscular fibre is composed of two parts —a proper substance called the sarcous element, in which the contractile property resides, and a sheath or sarcolemma, a transparent, structureless mem- brane, in which is contained the contractile substance. These element- ary fibres are connected by areolar tissue, with which a little fat is often associated. Lying between these fibres are blood vessels, nerves, and lymphatics. The sarcous element is a soft, granular material, on the varying relations of which granules to each other depend the alterations in a^apearance of the striae. If they approach each other more closely in the direction of the length of the fibre than in its width, it will appear fibrillated; if the reverse, it will present the appear- ance of discs. Muscles, like all other tissues, are developed from germinal matter which has undergone special metamorphosis, under the impulse of the parent cell, to construct this tissue. Germinal matter and formed material constitute the elementary part,—according to Mr. Beale —or the muscular cell of other writers from which the muscular fibre is formed. In the formed material, which is the constructed muscle, resides the power of contraction. The germinal matter or constructive part does not possess this property. Following the arrangement of Mr. Gray, we shall divide the muscles which it is our jDurpose to describe into certain groups, as follows:— 1. Nasal Group. 2. Superior Maxillary Group. Pyramidalis Nasi. Levator Labii Superioris Proprius. Levator Labii Superioris Alseque Nasi. Levator Anguli Oris. Levator Proprius Alae Nasi Posterior. Zygomaticus Major. Levator Proprius Alse Nasi Anterior. Zj^goraaticus Minor. Compressor Naris. Compressor Narium Minor. 3. Inferior Maxillary Group. Depressor Alse Nasi. Levator Labii Tnferioris. Depressor Labii Inferioris. Depressor Anguli Oris.