THE ABDOMEN 



657 



Nerve-supply. — ^This is similar to that of the internal oblique. 



Action. — ^To diminish the capacity of the abdominal cav-ity, and 

 so compress the viscera. To a limited extent the two muscles aid 

 the external and internal oblique muscles in elevating the pelvis, 

 flexing the thorax, and depressing the ribs. 



The most of the fibres pass transversely for^vards, and terminate 

 in the anterior aponeurosis. The Poupart fibres, however, pass 



-Posterior Wall of Sheath 

 of Rectus 



Posterior Aponeurosis of r 



Tranversalis Abdominis ~^ 



Semilunar Fold of 

 Douglas 



Band of Hei.le 



Rectus Abdominis (cut) 



Fig. 285. — The Transversalis Abdominis Muscle. 



flownwards and inwards, and join the corresponding fibres of the 

 internal oblique to form the conjoined tendon. The anterior 

 aponeurosis is narrow above, but broad below. Over about the 

 upper three-fourths of the rectus abdominis it passes behind the 

 mascle, but over about the lower fourth it passes in front of it. 

 The transversalis abdominis is continuous superiorly with the 

 triangularis sterni muscle, and its lower border is free where it 

 arches over the spermatic cord, or the round ligament of the uterus. 



42 



