ABDOMEN. 



Fig. 3. 



c, the internal oblique ; e, the descending fibres ; /, 

 point, of insertion into the pubis ; h, one of the re- 

 versed arches ; d, conjoined tendons ; a, rectus 

 muscle. 



good deal diminished in size, crosses over the 

 inferior and anterior portion of the tunica vagi- 

 nalis testis, and begins to ascend along the inner 

 side of the testicle and cord, keeping more pos- 

 teriorly : this constitutes the second bundle ; it 

 gradually increases in size as it ascends by re- 

 ceiving the transverse fibres from the bundle of 

 the opposite side, and it is inserted, sometimes 

 by a distinct tendon, into the pubis near its spine. 

 In some cases I have totally failed, even after 

 the most careful dissection, in detecting a conti- 

 nuity by muscular fibre between these two bun- 

 dles, insomuch as to lead me to imagine that 

 they may be connected by a very condensed cel- 

 lular tissue or thin aponeuro^c lamella after the 

 manner of the digastric musaj^s. . In general the 

 external bundle is largej^han the internal, but 

 Cloquethas seen the re^K three times ; and on 

 referring to my notes, I mjd I have seen two 

 instances in which the internal bundle exceeded 

 the external in size. V 



Many anatomists have notic^ed only the ex- 

 ternal bundle of the cremaster? and altogether 

 overlooked its reversed arches, which is not to 

 be wondered at when we remember that even 

 where the lateral bundles are strong and well 

 developed, the arched fibres are sometimes pale 

 and thin. However, the description now 

 given is pretty generally admitted as the true 

 one, and is sanctioned by such observers as 

 Scarpa, Cloquet, Cooper, Velpeau, and I may 

 add that I have seen this arrangement in cases 

 where both testicle and cord were healthy. It 

 would appear that its formation is effected by 

 the testicle in its descent, for before that takes 

 place the muscle does not exist ; at least such is 

 the result of Cloquet's observations on a con- 

 siderable number of foetuses before, during, and 

 after the descent of this organ. Before the de- 

 scent the gubernaculum testis occupies the 

 inguinal canal, and is covered by the fibres of 

 the internal oblique, which adhere to it : when 



the gubernaculum is drawn down, these fibres 

 descend with it, forming a series of reversed 

 arches. 



In some female subjects we see an arrange- 

 ment of the inferior fibres of the internal oblique 

 as they cross over the round ligament, which 

 resemble a rudimentary state of the cremaster 

 muscle. 



A thin layer of cellular tissue, sometimes 

 containing a small quantity of fat, is interposed 

 between the anterior surface of the obliquus 

 internus and the obliquus externus. At the infe- 

 rior edge of the obliquus internus the spermatic 

 cord is seen emerging from the abdomen and 

 passing obliquely inwards and a little down- 

 wards to the external abdominal ring. Here it lies 

 in a groove or channel, called the inguinal canal, 

 which extends from the point at which the 

 spermatic cord emerges from the abdomen, (the 

 opening in the fascia transversalis called in- 

 ternal abdominal ring) to the external abdo- 

 minal ring. This canal is bounded or covered 

 anteriorly by the tendon of the obliquus 

 externus; posteriorly by the fascia trans- 

 versalis and some fibres of the tendon of the 

 transversalis muscle towards the inner side ; 

 superiorly by the margin of the obliquus in- 

 ternus and transversalis muscles ; and inferiorly 

 by the groove of Poupart's ligament.* (A full 

 description of this canal will be found in the 

 article GROIN, REGION OF THE.) 



3. Transversalis ( lumbo-abdominal, lumbo- 

 ili-abdominal). This muscle is immediately 

 under cover of the obliquus internus ; its name 

 is derived from the transverse direction of its 

 fibres. In its general character it resembles 

 the obliqui, being like them a muscular lamella, 

 inserted into a tendinous expansion, which 

 again is inserted into the linea alba. Supe- 

 riorly the fleshy fibres of this muscle are attach- 

 ed by distinct bundles to the internal surface 

 of the cartilages of the ribs forming the lower 

 margin of the thorax, where these bundles in- 

 digitate with those of the diaphragm : 2dly, in 

 the interval between the last rib and the crista 



Fig. 4. 



* " The obliquus internus corresponds to the in- 

 ternal intercostals by the direction of its fibres, 

 by its being situated under cover of the obliquus 

 externus, and because its fleshy fibres extend much 

 further forwards than those of the last-named mus- 

 cle. " 



