THE MUSCLES OF THE ABDOMINAL WALL. 



477 



RECTUS ABDOMINIS 



The superior part of the aponeurosis covers the insertion of the rectus abdominis 

 muscle on the chest wall, and gives origin to fibres of the pectoralis major. In- 

 teriorly, in the groin, the lower part of the aponeurosis gives rise to the inguinal 

 ligament, the ligamentum lacunare, the two crura of the subcutaneous inguinal 

 ring, the external spermatic fascia and the intercrural fibres, and the ligamentum 

 inguinale reflexum of Colles. 



Lig. Inguinale [Pouparti]. The inguinal ligamentum (O.T. Poupart's ligament) 

 is an aponeurotic band which extends from the anterior superior iliac spine to the 

 tubercle of the pubis, arching over the iliacus, psoas, and pectineus muscles. It repre- 

 sents the inferior margin of the aponeurosis of the obliquus externus abdominis, and 

 it gives attachment below to the iliac portion of the fascia lata of the thigh. Its 

 lateral part affords partial origin to the obliquus internus and transversus muscles, 

 and receives the attachment of the fascia transversalis and fascia iliaca ; the medial 

 part forms the gutter-like floor of the inguinal canal. At its medial end a triangular 

 band of fibres is 

 reflected horizon- 

 tally backwards to 

 the ilio-pectineal 

 line, forming the 

 lig. lacunare [Gim- 

 bernati] (O.T. Gim- 

 bernat's ligament), 

 the lateral edge 

 of which forms 

 the medial bound- 

 ary of the femoral 

 ring. The femoral 

 vessels, enclosed in 

 the femoral sheath, 

 enter the thigh 

 posterior to the 

 inguinal ligament, 



On the anterior Posterior aponeurosis 



surface of the psoas 

 major muscle, and 

 the term super- 

 ficial femoral arch 

 is given to the 

 part of the liga- 

 ment which covers 

 the vessels. 



Annulus In- 

 guinalis Subcu- 



taneus. The subcutaneus inguinal ring (O.T. external abdominal ring), the place of 

 exit of an inguinal hernia, is a split in the aponeurosis of the obliquus externus, 

 just above the tubercle of the pubis. It transmits the spermatic funiculus, or 

 (in the female) the round ligament of the uterus, covered by the cremaster 

 muscle or cremasteric fascia. The opening is of considerable extent, and its 

 edges are drawn together by a thin fascia, strengthened superficially by a number 

 of arched and horizontal fibres, called the intercrural fibres, which arise from the 

 inguinal ligament and sweep medially across the cleft in the aponeurosis. 



The margins of the ring constitute its crura. The inferior eras is narrow, and 

 is formed from that part of the aponeurosis which joins the pubic tubercle, and is 

 continuous with the medial end of the inguinal ligament. The superior eras is the 

 part of the aponeurosis medial to the ring which is attached to the crest and 

 symphysis of the pubis. It is flat and broad. 



The intercrural fibres and the crura of the subcutaneous inguinal ring are 

 continuous with a thin tubular sheath, the intercolumnar or external spermatic fascia, 

 which is attached to the margins of the " ring," and forms an envelope for the 



OBLIQUUS EXTERNUS 



OBLIQUUS INTERNUS 

 TRANSVERSUS 



ABDOMINIS 



Fascia transversalis 

 Peritoneum 



Colon 



Extra peritoneal 

 tissue 



Kidney 



of transversu 

 LATISSIMUS DORSI 



QUADRATUS LUMBORUM 



Psoas fascia % 



Second lumbar 

 vertebra 



PSOAS MAJOR 



Anterior layer of 



lumbo-dorsal 



fascia 



MULTIFIDUS 



SEMISPINALIS 

 DORSI 



Middle layer of lumbo-dorsal fascia 



ILIOCOSTALIS 



Posterior layer of lumbo-dorsal fascia 



LONGISSIMUS DORSI 



FIG. 423. TRANSVERSE SECTION THROUGH THE ABDOMEN, OPPOSITE THE 

 SECOND LUMBAR VERTEBRA. 



