Volume 1

A text-book of human physiology : including histology and microscopical anatomy with special reference to the requirements of practical medicine / by L. Landois ; translated from the seventh German edition with additions by William Stirling.

Landois, L. (Leonard), 1837-1902. Lehrbuch der Physiologie des Menschen. English

Date:: 1891

Credit: A text-book of human physiology : including histology and microscopical anatomy with special reference to the requirements of practical medicine / by L. Landois ; translated from the seventh German edition with additions by William Stirling. Source: Wellcome Collection.

147/602 page 107

$branched protoplasmic cells lie embedded within a corresponding system of plasma canals. Outside this is an elastic lamina (b), basement membrane, or membrana propria, which in the smallest arteries is a structureless or fibrous elastic membrane—in arteries of medium size it is a fenestrated membrane {Henle), while in the largest arteries there may be several layers of elastic laminse or fenestrated elastic membrane mixed with connective tissue. [In some arteries the elastic membrane is distinctly fibrous, the fibres being chiefly arranged longitudinally. It can be stripped off, when it forms a brittle elastic membrane, which has a great tendency to purl up at its margins. In a transverse section of a middle-sized empty artery it appears as a bright wavy line, but the curves are produced by the partial collapse of the vessel. It forms an important guide to the pathologist, in enabling him to determine Avhich coat of the artery is diseased.] In middle-sized and large arteries a few non-striped muscular fibres are disposed longittidinalhj between the elastic plates or laminae. Along with the circular muscular fibres of the middle coat, they may act so as to narrow the artery, and they may also aid in keeping the lumen of the vessel open and of uniform calibre. (2) The tunica media, or middle coat, contains much non-striped muscle (c), which in the smallest arteries, sometimes called arterioles, consists of transversely disposed non-striped Fig. 80. Transverse section of a small artery, vein, and nerve. A, artery; a, its endothelium ; &, elastic lamina ; c, muscular coat, with its rod-shaped nuclei ; d, adventitia. _ V, vein; a, its endo- thelium ; h, thin elastic lamina; c, thin muscular coat; d, adventitia ; /, fat. N, trans- verse section of a nerve. muscular fibres lying between the endothelium and the T. adventitia, while a finely granular tissue with few elastic fibres forms the bond of union between them. As we proceed from the very smallest to the small arteries, the number of muscular fibres become so great as to form a well- marked fibrous tube of non-striped muscle, in which there is comparatively little connective- tissue. In the large arteries the amount of connective-tissue is considerably increased, and be- tween the layers of fine connective-tissue numerous (as many as 50) thick, elastic fibrous or fenestrated laminse are concentrically arranged. A few non-striped fibres lie scattered amongst these, and some of them are arranged transversely, wliile a few have an oblique or longitudinal direction. The first part of the aorta and pulmonary artery, and the retinal arteries, aie devoid of muscle. The descending aorta, common iliac, and popliteal have longitudinal fibres between the transverse ones. Longitudinal bundles lying inside the media occur in the renal, splenic, and internal spermatic arteries. Longitudinal bundles occur both on the outer and inner surfaces of the umbilical arteries, which are very muscular. (3) The tunica adventitia, or outer coat, in the smallest arteries consists of a structureless membrane with a few connective-tissue corpuscles attached to it ; in somewhat larger arteries there is a layer of fine fibrous elastic tissue mixed with bundles of fibrillar connective-tissue {d). In arteries of middle-size, and in the largest arteries, the chief mass consists of bundles of fibrillar connective-tissue containing connective-tissue corpuscles. The bundles cross each other in a variety of directions, and fat cells often lie between them. Next the media there are numerous fibrous or fenestrated elastic lamellae. In medium-sized and small arteries the elastic tissue next the media takes the form of an independent elastic membrane (Henle's external elastic membrane). Bundles of non-striped muscle, arranged longitudinally, occur in the adventitia of the arteries of the penis, and in the renal, splenic, spermatic, iliac, hypogastric, and superior mesenteric arteries.$