THE TRAN8VEM8ALIB MUSCLE. 1045 



of the external abdominal ring and in front of the conjoined tendon, and interlaces 

 with the ligament of the other side at the linea alba. 



The Internal oblique muscle has been previously described (page 360). The 

 part which is now exposed is partly muscular and partly tendinous in structure. 

 Those fibres which arise from Poupart's ligament, few in number and paler in 

 color than the rest, arch downward and inward across the spermatic cord, and, 

 becoming tendinous, are inserted, conjointly with those of the Transversalis, into the 

 crest of the us pubis and pectineal line, forming what is known as the conjoined 

 tendon of the Internal oblique and Transversalis. This tendon is inserted imme- 

 diately behind the inguinal canal and external abdominal ring, serving to protect 

 what would otherwise be a weak point in the abdominal wall. Sometimes this 

 tendon is insufficient to resist the pressure from within, and is carried forward in 

 front of the protrusion through the external ring, forming one of the coverings of 

 direct inguinal hernia, or the hernia forces its way through the fibres of the con- 

 joined tendon. 



The Cremaster is a thin muscular layer composed of a number of fasciculi 

 which arise from the middle of Poupart's ligament at the inner side of the Internal 

 oblique, being connected with that muscle and also occasionally with the 

 Transversalis. It passes along the outer side of the spermatic cord, descends with 

 it through the external ring upon the front and sides of the cord, and forms a 

 series of loops which differ in thickness and length in different subjects. Those 

 at the upper part of the cord are exceedingly short, but they become in succession 

 longer and longer, the longest reaching down as low as the testicle, where a few 

 are inserted into the tunica vaginalis. These loops are united together by areolar 

 tissue, and form a thin covering over the cord and testis, the fascia cremasterica. 

 The fibres ascend along the inner side of the cord, and are inserted by a small 

 pointed tendon into the crest of the os pubis and front of the sheath of the Rectus 

 muscle. 



It will be observed that the origin and insertion of the Cremaster is precisely 

 similar to that of the lower fibres of the Internal oblique. This fact affords an easy 

 explanation of the manner in which the testicle and cord are invested by this muscle. 

 At an early period of foetal life the testis is placed at the lower and back part of the 

 abdominal cavity, but during its descent toward the scrotum, which takes place 

 before birth, it passes beneath the arched border of the Internal oblique. In its 

 passage beneath this muscle some fibres are derived from its lower part which 

 accompany the testicle and cord into the scrotum. 



It occasionally happens that the loops of the Cremaster surround the cord, some 

 lying behind as well as in front. It is probable that under these circumstances 

 the testis in its descent passes through, instead of beneath, the fibres of the Internal 

 oblique. 



In the descent of an oblique inguinal hernia, which takes the same course as 

 the spermatic cord, the Cremaster muscle forms one of its coverings. This muscle 

 becomes largely developed in cases of hydrocele and large old scrotal hernias. No 

 such muscle exist in the female, but an analogous structure is developed in those 

 cases where an oblique inguinal hernia descends beneath the margin of the Internal 

 oblique. 



The Internal oblique should be detached from Poupart's ligament, separated from the 

 Transversalis to the same extent as in the previous incisions, and reflected inward on to the 

 sheath of the Rectus (Fig. 581). The deep circumflex iliac vessels, which lie between these two 

 muscles, form a valuable guide to their separation. 



The Transversalis muscle has been previously described (page 362). The part 

 which is now exposed is partly muscular and partly tendinous in structure ; it 

 arises from the outer third of Poupart's ligament, its fibres curve downward and 

 inward, and are inserted, together with those of the Internal oblique, into the lower 

 part of the linea alba, into the crest of the os pubis and the pectineal line, form- 

 ing what is known as the conjoined tendon of the Internal oblique and Trans- 



