FASCIA 



427 



to the diaphragm. In the region of the iUac fossa the transversalis fascia is reflected from the 

 transversus muscle to the ilio-psoas fascia, with which it usually becomes fused. Sometimes, 

 however, it may be traced as a very dehcate membrane over "the iliac artery and vein. As 

 these vessels pass below the inguinal ligament a process from the transversaUs fascia is usually 

 reflected into their sheath. 



The sheath of the rectus (figs. 384, 407) is formed externally in the upper portion of its 

 extent by the aponeurosis of the external oblique which fuses distal to the costal margin with 

 the external layer of the aponeurosis of the internal oblique. In the lower portion of the abdo- 

 men this fusion takes place nearer the linea alba than in the upper portion. In the lower third 

 of its extent the rectus is covered ventrally by the fused aponeuroses of the two obhque muscles 

 conjoined with that of the transversus. Internally the rectus is covered in the upper two-thirds 

 of the abdomen by the inner layer of the aponeurosis of the internal oblique conjoined with that 

 of the transversus and bj' the transversalis fascia. In the lower third of the abdomen the ap- 

 oneurosis of the internal oblique, together with that of the transversus, passes in front of the 

 rectus, leaving the rectus in this portion of its abdominal surface covered merely by the trans- 

 versaUs fascia and the peritoneum. The line which marks the lower limit of the dorsal ensheath- 

 ment of the rectus by the aponeurosis of the transversus muscle is called the linea semicircularis, 



Fig. 386. — The Muscles attached to the Back of the Sternum. 



Sterno-hyoid 



Sterno-thyreoid 



Transversus 

 thoracis 



Sternal origin jf 

 of diaphragm ,?' 



Costal origin 

 of diaphragm 



Transversus abdominis 



or fold of Douglas. Between the transversalis fascia and the rectus just above the pubis 

 there is a space filled with loose connective tissue or with fat. 



The pyramidalis lies beneath the ventral layer of the sheath of the rectus. From the latter 

 it is sometimes separated by a distinct fascial layer. 



Between the rectus muscles of each side the investing aponeuroses are firmly united into 

 a dense tendinous band, the linea alba (fig. 389). This is broadest opposite the umbilicus. 

 Above this it gradually grows narrower toward the xiphoid process to the ventral surface of 

 which it is attached. From the tip of the xiphoid process it is often separated by a bursa. 

 Toward the symphysis pubis it extends as a narrow line. Just above the symphysis it divides 

 to be attached on each side to the tubercle (spine) of the pubis. Behind it broadens into the 

 adminiculum lineoe albce which is attached on each side to the pubis. The linea alba is composed 

 mainly of the interlacing of the fibres which pass into it from the aponeurotic sheaths of the 

 rectus abdominis. From it and Scarpa's fascia, a few centimetres above the symphysis, there 

 arises a broad elastic band, the f undif or m ligament (superficial suspensory ligament) of the penis, 

 which sends a fasciculus on each side of the penis. Below the penis these fascicuh unite.* At 

 the umbilicus there is a circular opening encircled by dense fibrous tissue and filled with a thick 

 connective tissue, extending from the tela subcutanea to the subserosa. 



* Alex. Hagenton has shown that the linea alba varies much in width. It is relatively wide 

 in fat people and in foetuses. 



