REGION OF THE.) The external abdominal ring is a triangular opening, situated obliquely ; the superior angle being directed upwards and outwards, and its base, represented by a line uniting the pubic insertions of the two pillars, resting upon the pubis. The superior angle is formed evidently by the separation of the fibres of the aponeu rosis, the primitive direction of which is the same as that of a perpendicular from the apex to the base of the triangle, viz. downwards and in wards, (sacrad and pubad.) This separation, however, is strengthened, and the angle round ed by some tendinous fibres which inter sect the oblique ones nearly at a right angle, arising as a cord of variable thickness from Poupart's ligament, and passing upwards and inwards over the apex of the ring, gradually separating into several tendinous fibres. These fibres are sometimes very strong, at other times very feeble and scarcely perceptible ; but it rarely, if ever, happens that they are completely absent ; they have been termed intercolumnal bands. I have seen them so strong that they could be distinctly dissected off the external oblique aponeurosis, like a separate tendinous expansion; but most fre quently they are so united to the aponeurosis as to render it impossible to remove them without injury to it. These fibres are evi dently intended, as Scarpa expresses it, " to fix the limits of the inguinal ring, and to oppose the further divergence of the tendi nous pillars towards the side." They are equally met. with, although not nearly so much developed, in women and children as men ; and Mr. Lawrence asserts that in old herniae they are particularly strong. I cannot confirm this remark from my own observation, as in my dissections of old herniae, I have not found them particularly developed; nor is it con sistent with the general result of pressure from within on tendinous fibres to believe that such pressure would produce an increase of deve lopment in them.
The size of the external abdominal ring is greatest in the male subject, but here it varies considerably, sometimes closely embracing the cord as it passes through it, and at others appearing much too large for it. In the male the parts which pass through it are the sper matic cord, enveloped in its proper tunic, and in one of condensed cellular membrane pro longed from the fascia transversalis, a branch of the genito-crural nerve, the cremaster mus= cle, the cremasteric artery, and the spermaticus superficialis nerve. In the female, we find
the round ligament of the uterus, covered and accompanied by similar parts, excepting the cremaster. From the margin of the external abdominal ring, a cellular expansion or fascia is carried over the cord or round ligament, and has been denominated spermatica. This fascia consequently forms a covering of any hernia that may be protruded through the external ring; and, accordingly, in old herniae we find it greatly thickened. Its formation is simply in accordance with what we find oc curring in all parts of the body, viz. that when any part passes through an opening in a fibrous membrane, it carries with it a cellular expan sion from the margin of that opening. This we observe in the passage of the vena cava through the diaphragm, of the urethra through the triangular, ligament or deep perineal fascia. This view confirms the opinion of Sir A. Cooper, that this fascia is a production from the margin of the ring itself.
The external oblique muscle is covered in all its extent by the superficial fascia ; its costal margin is related to the serrates magnus, and to the latissimus dorsi, with which muscle it is also in close relation by its posterior margin, being sometimes slightly overlapped by the anterior margin of the latissimus, but at others separated from that muscle by a triangular interval through which the fibres of the obliquus inter nus appear : inferiorly the fascia lata of the thigh is related to the margin of the external oblique muscle, both as it covers the glutoei, and as it lies in front of the thigh. Along the middle line the aponeuroses of opposite sides meet at the linea alba, and superiorly the mus cular fibres are related to and sometimes con nected by a fleshy slip with those of the pecto ralis major, and the aponeurosis is continuous with that of the same muscle.* When the ex ternal oblique is removed from its osseous at tachments, and raised inwards, it is found to cover the internal oblique, with part of the ten don of which it is ultimately united as the two tendons approach the linea alba.