ABDOMEN. 



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. 



2. Obliquus internus (obliquus ascendens, 

 ilio-abdominal, ilio-lumbo-costi-abdominal) is 

 smaller than the preceding muscle, which it 

 resembles in shape and general characters. The 

 direction of its fibres, however, is opposite, 

 inasmuch as the fibres of the two muscles 

 decussate with each other, thus adding con- 

 siderably to the strength of the abdominal wall, 

 and forming a great protection against visceral 

 protrusions. The external attachments (or, as 

 systematic writers call it, the origin of the mus- 

 cle) is 1. by short fleshy fibres to the tendinous 

 expansion covering the lumbar mass of muscles, 

 called fascia lumborum, which is formed by 

 the posterior lamina of the tendon of the trans- 

 versalis abdominis : 2. to the two anterior 

 thirds of the middle portion of the crista ilii, 

 between the external oblique and the transver- 

 salis as far forwards as the anterior superior 

 spine : 3. to the groove in the upper or abdo- 

 minal surface of Poupart's ligament for about 

 its external third. The superior fibres pass 

 upwards and inwards, and are inserted by 

 fleshy slips into the cartilages of the twelfth, ele- 

 venth, and tenth ribs, in the intervals between 

 which they are either separated from the inter- 

 costal muscles by a fibrous intersection, or con- 

 founded with them, and by a tendinous aponeu- 

 rosis into the cartilages of the ninth, eighth, and 

 seventh ribs as well as into the xiphoid cartilage. 

 Lower down, the fibres which arise from the 

 crista ilii, as well as those from Poupart's liga- 

 ment, pass inwards, the superior obliquely 

 upwards and inwards, the inferior more hori- 

 zontally, and the lowest fibres inclining a little 

 downwards, and are all inserted, like those of 

 the obliquus externus into the outer convex 

 margin of an aponeurotic expansion,, which goes 

 to be inserted along the middle line. This ten- 

 don passes inwards for a short distance, nearly 

 as far as the outer margin of the rectus muscle, 

 as a single lamina. Along this margin, and as 

 low down as the inferior fourth of the rectus 

 muscle, the tendon divides into two laminae, 

 of which the anterior adheres to the posterior 

 surface of the tendon of the external oblique, 

 and the posterior to the subjacent tendon of the 

 transversalis, both laminae going to be inserted 

 into the ensiform cartilage and linea alba, the 

 one in front, the other behind, the rectus muscle. 

 (Seej%. 4, a. ) For a distance, however, corres- 

 ponding to the inferior fourth of the rectus 

 muscle, the tendon of the obliquus internus re- 

 mains undivided, and does not adhere to that of 

 the obliquus externus. It, however, is united, 

 although not inseparably, to the tendon of the 

 transversalis, and both go in front of the rectus 

 to be inserted into the linea alba and pubis : 

 these tendons are here called by some the con- 

 joined tendons. Along the line at which the 

 tendon of the obliquus internus divides into two 

 laminae., the aponeurosis of the obliquus externus 



and that of the trausversalis adhere to it more 

 closely than they do externally to that line, and 

 thus a thickened portion of the abdominal 

 aponeurosis is formed, taking the course of the 

 outer margin of the rectus muscle : this line is 

 called the Linea semilunaris, and is that in which 

 the operation of paracentesis abdominis used 

 formerly to be practised. 



The inferior margin of the obliquus internus 

 is deserving of particular attention. The in- 

 ferior fibres attached to the external third of 

 Poupart's ligament in the groove formed in it 

 pass transversely inwards and parallel to the 

 ligament, crossing over the spermatic cord, to 

 be inserted into the pubis. Here the muscle is 

 confounded with the inferior fibres of the sub- 

 jacent one, the transversalis ; so that it is not 

 only difficult to say which muscle passes low- 

 est down, but it is difficult, and often impossible, 

 to separate the two muscles. Hence the lower 

 margins of the fleshy fibres as well as of the apo- 

 neuroses of these two muscles are constantly 

 spoken of conjointly ; however, I have several 

 times succeeded in separating them distinctly, 

 and I am decidedly of opinion that the apo- 

 neurosis of the obliquus internus seldom or 

 never descends so low down as that of the trans- 

 versalis. The lowest of the fibres of the obliquus 

 internus are sometimes observed to separate a 

 little from the others, so as, instead of a directly 

 transverse, to assume a course slightly curved 

 with the concavity upwards and a little outwards, 

 lying in front of the cord ; in some cases fibres 

 of this kind are observed to lie in front of th^ 

 spermatic cord, and to descend much lower 

 down, taking of course a much more curved 

 direction, still attached on the outside to Pou- 

 part's ligament, and on the inside to the pubis, 

 so that a series of curved fibres are thus found 

 to adhere to the anterior surface of the cord and 

 of the tunica vaginalis, exhibiting an equal num- 

 ber of reversed arches. But this disposition is 

 rarely seen in its most highly developed state, 

 excepting where some tumour has been con- 

 nected with the cord or testicle, as hernia, 

 hydrocele, &c. 



This arched arrangement of muscular fibres 

 in connection with the spermatic cord and 

 tunica vaginalis testis constitutes the Cremas- 

 ter muscle (K^^atu, suspendo,} the great tenuity 

 of which in the natural state of the parts has ren- 

 dered it difficult to determine its precise attach- 

 ments, and consequently has given rise to the 

 great discrepancy which is observable between 

 the descriptions of different writers. When 

 this muscle is examined in a case of old hernia 

 or hydrocele, it is found, as Scarpa originally 

 described it, to consist of two bundles ; the first, 

 external to the cord which arises from Poupart's 

 ligament along with the internal oblique, follows 

 the course of the spermatic cord, which it ac- 

 companies through the external abdominal ring, 

 sending at intervals fibres arching in front of 

 the cord to join a similar bundle on the inner 

 side, as may be seen in the accompanying en- 

 graving from a plate in Sir A. Cooper's work 

 on the testis (fig. 3 ). Inferiorly, this bundle, a 



