THE TRANSVERSALIS ABDOMINIS MUSCLE. 333 



and inferiorly, where that aponeurosis passes entirely in front of the rectus, it takes 

 a similar position in relation to that muscle. 



The posterior aponeurosis of the transversalis springs by strong fibrous bundles 

 from the tips of the transverse processes of the lumbar vertebrae, and extends out- 

 wards to the commencement of the fleshy fibres, being placed between the erector 

 spinae and quadra tus lumborum muscles. Superiorly it is attached to the lower 



Fig. 295. LATERAL VIEW OF THE TRUNK, 



SHOWING THE SERRATUS MAGNUS AND 

 TRANSVERSALIS ABDOMINIS MUSCLES. 



(Allen Thomson.) \ 



For the explanation of the references 

 in the upper part of the figure see the 

 description of fig. 230, p. 212. 



e, placed on the pubis, points to the 

 insertion of Gimbernat's ligament ; YI, 

 XII, sixth and twelfth ribs ; L 1 , first 

 lumbar vertebra ; 5, costal origins of the 

 transversalis abdominis ; 6, origin of the 

 muscle from the transverse processes of 

 the lumbar vertebras by the lumbar apo- 

 neurosis ; 6', part arising from the crest 

 of the ilinm ; 7, lower portion arising 

 from the outer part of Poupart's liga- 

 ment ; 8, sheath of the rectus muscle 

 opened in its upper part by removing the 

 aponeurosis of the oblique muscles ; 9, 

 the same in its lower part left entire at 

 the place where the tendons pass wholly 

 in front of the rectus muscle ; 10, inter- 

 spinales muscles ; 11, gluteus minimus ; 

 12, pyriformis. 



border of the last rib, and infe- 

 riorly to the ilio-lumbar ligament 

 and the adjoining part of the 

 iliac crest. This membrane con- 

 stitutes the middle layer of the 

 lumbar fascia ; it is joined be- 

 hind, at the outer edge of the 

 erector spinae, by the posterior 

 layer, and in front, more exter- 

 nally, at the outer edge of the 

 quadratus, by the anterior layer 

 of that structure. 



Relations. Between the outer 

 surface of this muscle and the in- 

 ternal oblique are placed the lower 

 intercostal nerves and a branch of the 

 circumflex iliac artery : its inner sur- 

 face is lined throughout by the trans- 

 versalis fascia, which separates it from the subperitoneal tissue and the peritoneum. The highest 

 part of the transversalis is continued into the triangularis sterni muscle of the thorax. 



Varieties. The transversalis has been found fused with the internal oblique, or entirely 

 absent. The spermatic cord has been seen to pierce its lower border. Slender muscular slips 

 have been observed arising from the ilio-pectineal line behind the conjoined tendon, and 

 inserted into the transversalis fascia, the aponeurosis of the transversalis muscle ^bo-trans- 

 n-rsalis, Luschka), or the outer end of the semilunar fold of Douglas. 



The rectus abdominis is a long flat muscle, consisting of vertical fibres, 

 situated at the fore part of the abdomen, within a tendinous sheath formed in the 

 manner already described in the account of the aponeurosis of the internal oblique 



