Human physiology / by John Thornton.

  • Thornton, John
Date:
1899
Catalogue details

Licence: Public Domain Mark

Credit: Human physiology / by John Thornton. Source: Wellcome Collection.

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    muscle is found in the muscular coat of the alimentary canal below the middle of the oesophagus, in the trachea and bronchi, in the middle coat of the arteries, the coats of many veins and the larger lymphatics, in the bladder and ureters, and in the ducts of glands. It also occurs in the iris and ciliary muscle, and in the true skin, especially between the bases of the papillae. When it contracts in the skin under the influence of cold or fear, or any other stimulus, it causes the papillae to become unusually prominent, thus producing the peculiar roughness termed 'goose skin.^ (See par. 161.) Plain or non-striated muscular tissue is composed of spindle- shaped nucleated cells, somewhat flattened, and having a length seldom more than -^—^ of an inch and a breadth about one- eighth of the length. The oval nucleus exhibits the intranuclear network and one or two nucleoli. The cell-substance is longitudin- ally but not transversely striated, and each cell seems to have a delicate sheath. Between the fibres there is a small quantity of cementing substance. The fibres are collected together into bundles ensheathed in the con- nective tissue. The small blood- vessels run in the connective tissue, and from these capillaries pass between the individual fibres. Non-medullated nerves are supplied to plain muscular tissue from the sympathetic or ganglionic system, and this tissue responds but slowly to a stimulus, the contraction last- ing several seconds and spreading as a wave from fibre to fibre. 30. Cardiac Muscle.—The heart, though an involuntary muscle, contains fibres that present transverse marks or striae. But the fibres are smaller than those of voluntary muscle, and Fig. 27.—Muscular Fibre-cells from Human Arteries, Magnified 350 diameters. (Kolliker.) a, nucleus; B, a cell treated with acetic acid.
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