Volume 1

The cyclopaedia of anatomy and physiology / Edited by Robert B. Todd.

Date:
1836-59
Catalogue details

Licence: Public Domain Mark

Credit: The cyclopaedia of anatomy and physiology / Edited by Robert B. Todd. Source: Wellcome Collection.

    18/832 (page 4)
    AHDOM KN. 4^ below and carrying it upwards; llie expansion will then appear to arise from I’ouparl’s liga- ment, and spread over the subjacent aponeuro- sis. In some subjects it is so thin as to appear to be little more than the pro))er cellular cover- ing of the muscle and its aponeurosis, but in others it assumes a considerable degree of density. It may be called the deep layer of the superficial fascia; it deserves attention from the fact that the femoral hernia, in its ascent on the abdomen, lies between it and the super- ficial layer. It is to this fascia that Scarpa must allude under the name of “ aponeurotic web of the muscle of the fascia lata,” and hence some have called it Scarpa’s fascia.'* The whole of the superficial fascia has been called Camper’s fascia, because it was first fully described by that writer.f ()n the posterior wall of the abdomen, in the lumbar regions, the cellular tissue is more abundant and more lax; here we frequently find it infiltrated with serous fluid, in conse- quence of the usual supine posture of the body after death. It is continuous above with the subcutaneous tissue in the dorsal region, and below with that in the glutreal regions. It, too, is firmly adherent along the middle line to the lumbar spine anteriorly, and to the skin posteriorly. ;i. Muscles and aponeuroses.—The abdo- minal parietes owe their thickness chiefly to the muscular lamellse and the aponeurotic ex- pansions, which enter into their composition. In the anterior and lateral walls we find on each side five pairs of muscles, of which four are constantly present. These are, 1, M. obli- quus externus; 2, obliquus interims; 3, trans- versalis; 4, rectus abdominis ; 5, pyraniidalis, which last is frequently absent. 1. Obliquus externus. (Obliquus descen- dens ; costo-abdorninal ; ilio-pubi-costo-abdo- minal.) When the superficial fascia covering the an- terior and lateral surfaces of the abdomen has been dissected away, this muscle is brought into view. It consists of a flat muscular portion, situated superiorly and posteriorly, and of a tendinous or aponeurotic lamella anteriorly and inferiorly, but which is largest and strongest in the latter situation. The muscular portion of the external oblique is attached by separate fasciculi to the external surfaces of the eight inferior ribs, from the fifth to the twelfth inclusive. These fasciculi indigitate at their attachment with similar ones, of the serratus magnus, from the fifth to the ninth inclusive, and of the latissimus dorsi from the tenth to the twelfth. From these points of attachment, described by most English anatomists as the origin of the muscle, the fibres pass obliquely downwards and forwards, with different degrees of ob- liquity, the middle fibres being the most ob- * Vid. Scarpa on Hernia, by Wishart, p. 22; also Todd on Hernia, Dub. Hosp. Reports, vol. i. p. 246; and Flood’s plates of Inguinal and Femoral Hernia. I Camper, leones Hprniarum, p. 11. liipie, the superior taking u direction ne:irly horizontally inwards, and the posterior ones passing nearly vertically downwards. The an- terior and middle fil)ies are inserted into the outer convex border of tlie aiioneurolic lamella of the muscle, but the posterior are inserted into the outer lip of the two anterior thirds of the crista of the ilium by short tendinous fibres. The fibres of this muscle vary considerably in length, those which are highest up being the shortest, the middle ones the longest, and next in length the posterior fibres. The aponeurotic lamella of the external oblique muscle is found on the anterior part of the abdomen, both su- periorly and inferiorly. In the former situa- tion the aponeurosis is extremely thin and weak ; it is transparent, so that the upper extremity of the rectus muscle which it covers is visible through it. This, too, is the narrow- est portion of the aponeurosis, which increases in breadth, strength, and thickness as it de- scends. The aponeurosis, like the muscular portion, consists of a series of fibres, for the most part inclined obliquely downwards and inwards, excepting the superior ones, whose direction is horizontal. At several places these fibres are separated from each other so as to allow the subjacent muscle to be seen through the interval. At various parts the tendon is perforated by vascular apertures, which are oc- casionally so enlarged as to admit little peri- toneal prolongations to pass through them. Along the middle line, from the ensiform car- tilage to the symphysis pubis, the aponeurosis forms an interlacement with its fellow of the opposite side, and this interlacement with that of the subjacent aponeuroses constitutes the tendinous line called linea alba, which, as Velpeau observes, may be regarded as the centre in which all the fibrous elements of the abdomen terminate. Just above the symphysis pubis, the decussating fibres are not inter- mixed in the same manner as in other parts of the linea alba : there the bundle of one side . crosses anteriorly or posteriorly to that of the other, without any union of fibres, to be in- serted into the pubis of the side opposite to that from which it came. A little above and external to the pubis, a separation of the fibres of the tendon of the obliquus externus takes place, leaving an opening which is denominated the external abdominal ring, through which the rounded bundle composed of the spermatic vessels and duct (the spermatic cord) passes in the male, and the round ligament of the uterus in the female. The aponeurotic fibres which form the immediate boundaries of this opening are termed the pillars of the ring, of which one is superior, internal, and anterior, the other is in- ferior, external, and posterior, and passes behind the cord. External and inferior to this opening, we observe that the aponeurosis of the external oblique muscle is extended from the pubis to the anterior superior spine of the ilium. On the pubic side, the fibres, which are the same that form the inferior pillar of the ring, are in- serted into the spine of the pubis, and being