6 ABDOMEN. 



ternal oblique is removed from its osseous at- and that of the trarisversalis adhere to it more 



tachments, and raised inwards, it is found to closely than they do externally to that line, and 



cover the internal oblique, with part of the ten- thus a thickened portion of the abdominal 



don of which it is ultimately united as the two aponeurosis is formed, taking the course of the 



tendons approach the linea alba. outer margin of the rectus muscle : this line is 



2. Obliquus internus (obliquus ascendens, called the linea semilunaris, and is that in which 



ilio-abdominal, ilio-lumbo-costi-abdominal) is the operation of paracentcsis abdominis used 



smaller than the preceding muscle, which it formerly to be practised. 



resembles in shape and general characters. The The inferior margin of the obliquus internus 

 direction of its fibres, however, is opposite, is deserving of particular attention. The in- 

 inasmuch as the fibres of the two muscles ferior fibres attached to the external third of 

 decussate with each other, thus adding con- Poupart's ligament in the groove formed in it 

 siderably to the strength of the abdominal wall, pass transversely inwards and parallel to the 

 and forming a great protection against visceral ligament, crossing over the spermatic cord, to 

 protrusions. The external attachments (or, as be inserted into the pubis. Here the muscle is 

 systematic writers call it, the origin of the mus- confounded with the inferior fibres of the sub- 

 cle) is 1. by short fleshy fibres to the tendinous jacent one, the transversalis ; so that it is not 

 expansion covering the lumbar mass of muscles, only difficult to say which muscle passes low- 

 called fascia lumborum, which is formed by est down, but it is difficult, and often impossible, 

 the posterior lamina of the tendon of the trans- to separate the two muscles. Hence the lower 

 versalis abdominis: 2. to the two anterior margins of the fleshy fibres as well as of the apo- 

 thirdsofthe middle portion of the crista ilii, neuroses of these two muscles are constantly 

 between the external oblique and the transver- spoken of conjointly; however, I have several 

 salis as far forwards as the anterior superior times succeeded in separating them distinctly, 

 spine : 3. to the groove in the upper or abdo- and I am decidedly of opinion that the apo- 

 minal surface of Poupart's ligament for about neurosis of the obliquus internus seldom or 

 its external third. The superior fibres pass never descends so low down as that of the trans- 

 upwards and inwards, and are inserted by versalis. The lowest of the fibres of the obliquus 

 fleshy slips into the cartilages of the twelfth, ele- internus are sometimes observed to separate a 

 venth, and tenth ribs, in the intervals between little from the others, so as, instead of a directly 

 which they are either separated from the inter- transverse, to assume a course slightly curved 

 costal muscles by a fibrous intersection, or con- with the concavity upwards and a little outwards, 

 founded with them, and by a tendinous aponeu- lying in front of the cord ; in some cases fibres 

 rosis into the cartilages of the ninth, eighth, and of this kind are observed to lie in front of the 

 seventh ribs as well as into the xiphoid cartilage, spermatic cord, and to descend much lower 

 Lower down, the fibres which arise from the down, taking of course a much more curved 

 crista ilii, as well as those from Poupart's liga- direction, still attached on the outside to Pou- 

 ment, pass inwards, the superior obliquely part's ligament, and on the inside to the pubis, 

 upwards and inwards, the inferior more hori- so that a series of curved fibres are thus found 

 zontally, and the lowest fibres inclining a little to adhere to the anterior surface of the cord and 

 downwards, and are all inserted, like those of of the tunica vaginalis, exhibiting an equal num- 

 the obliquus externus into the outer convex ber of reversed arches. But this disposition is 

 margin of an aponeurotic expansion, which goes rarely seen in its most highly developed state, 

 to be inserted along the middle line. This ten- excepting where some tumour has been con- 

 don passes inwards for a short distance, nearly nected with the cord or testicle, as hernia, 

 as far as the outer margin of the rectus muscle, hydrocele, &c. 



as a single lamina. Along this margin, and as This arched arrangement of muscular fibres 

 low down as the inferior fourth of the rectus in connection with the spermatic cord and 

 muscle, the tendon divides into two laminae, tunica vaginalis testis constitutes the Cremas- 

 of which the anterior adheres to the posterior ter muscle (n^^oiu, suspendo,) the great tenuity 

 surface of the tendon of the external oblique, of which in the natural state of the parts has ren- 

 and the posterior to the subjacent tendon of the dered it difficult to determine its precise attach- 

 trans versalis, both laminae going to be inserted ments, and consequently has given rise to the 

 into the ensiform cartilage and linea alba, the great discrepancy which is observable between 

 one in front, the other behind, the rectus muscle, the descriptions of different writers. When 

 (See Jig. 4, a.) For a distance, however, corres- this muscle is examined in a case of old hernia 

 ponding to the inferior fourth of the rectus or hydrocele, it is found, as Scarpa originally 

 muscle, the tendon of the obliquus internus re- described it, to consist of two bundles ; the first, 

 mains undivided, and does not adhere to that of external to the cord which arises from Poupart's 

 the obliquus externus. It, however, is united, ligament along with the internal oblique, follows 

 although not inseparably, to the tendon of the the course of the spermatic cord, which it ac- 

 transversalis, and both go in front of the rectus companies through the external abdominal ring, 

 to be inserted into the linea alba and pubis : sending at intervals fibres arching in front of 

 these tendons are here called by some the con- the cord to join a similar bundle on the inner 

 joined tendons. Along the line at which the side, as may be seen in the accompanying en- 

 tendon of the obliquus internus divides into two graving from a plate in Sir A. Cooper's work 

 laminae, the aponeurosis of the obliquus externus on the testis (Jig. 3). Inferiorly, this bundle, a 



