Page:Structure and functions of the body; a hand-book of anatomy and physiology for nurses and others desiring a practical knowledge of the subject (IA structurefunctio00fiskrich).pdf/28

 those of motion, while the unstriped occur in the hollow organs, surrounding the cavity and in some cases lessening its capacity by their contraction.

An intermediate form of muscle known as cardiac muscle occurs in the heart. Here the fibers have striations but the nucleus is generally in the middle of the cell and the fibers branch and run together.

—Voluntary muscle (Leroy). A, Three voluntary fibers in long sections: a, three voluntary muscle fibers; b, nuclei of same; c, fibrous tissue between the fibers (endomysium); d, fibers separated into sarcostyles. B, Fiber (diagrammatic): a, dark band; b, light band; c, median line of Hensen; d, membrane of Krause; e, sarcolemma; f, nucleus. C: a, Light band; b, dark band; c, contracting elements; d, row of dots composing the membrane of Krause; e, slight narrowing of contracting element aiding in production of median line of Hensen.

In life muscle appears more or less translucent and is contractile and alkaline, but in death it loses its translucency and becomes rigid, at the same time giving off in decomposition much carbon dioxide, so that its reaction is acid. This phenomenon of the muscles becoming rigid in death is called rigor mortis and occurs generally a few hours after death, though it may come