. Biology of the vertebrates : a comparative study of man and his animal allies. Vertebrates; Vertebrates -- Anatomy; Anatomy, Comparative. A Jack of All Trades 205 pigment cells, deposits of glycogen and fat, smooth muscle cells, sweat glands, sebaceous glands, and hairs, the last three being downgrowths from the epidermis. The deeper parts of the corium form the subcutaneous layer, character- ized by the inclusion of masses of soft fat cells and by the looser weave of the felted reticulum, which allows greater freedom of motion to the under- lying muscles. Its blood supply may include a larg
. Biology of the vertebrates : a comparative study of man and his animal allies. Vertebrates; Vertebrates -- Anatomy; Anatomy, Comparative. A Jack of All Trades 205 pigment cells, deposits of glycogen and fat, smooth muscle cells, sweat glands, sebaceous glands, and hairs, the last three being downgrowths from the epidermis. The deeper parts of the corium form the subcutaneous layer, character- ized by the inclusion of masses of soft fat cells and by the looser weave of the felted reticulum, which allows greater freedom of motion to the under- lying muscles. Its blood supply may include a large fraction of the total amount of blood in the entire body. Some of the fibers of the subcutaneous region interlace with the fibers composing the connective tissue sheaths that envelop the muscles, thus fastening the skin down, as it were, more firmly. This is demonstrated better in the palm than over the back of the hand where the skin is looser. Friction Sweat Corneal Layer Malpighian Layer. Sweat Gland — Derma--- Nerve--- Fig. 139. Diagram showing some of the details of friction skin. The ridges on the surface, matched by corresponding epidermal projections into the derma, are penetrated by the ducts of the sweat glands which lie coiled up in the derma below. Two sensory papillae are shown. (After Wilder and Wentworth.) In regions of the body such as the finger tips that are much in contact with things, the outer part of the corium just under the epidermis is thrown up into rows of tiny projections, or papillae, that form ridges (Fig. 139). It is customary consequently to speak of a papillary layer of the corium, although stratification of the corium is not as pronounced as stratification of the epidermis. The roughened papillary layer helps possibly to hold the corium and epidermis together at points on the skin where friction or pres- sure is frequently applied, for the epidermis dovetails intimately into the minute hills and valleys formed by the dermal papillae. There
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Keywords: ., bookcentury1900, booksubjectanatomycomparative, booksubjectverte
