THE VENTRAL MUSCLES. 



523 



In the lower part of the anterior abdominal wall the lowermost fibres of the 

 abdominal aponeurosis — those extending between the anterior superior spine of the 

 ilium and the pubic spine — form a strong ligamentous band, the ligament of Pou- 

 part ( liganientum inguinale) (Figs. 524, 530J, the outer portion of which gives rise to 

 some of the fibres of the internal oblique and transversalis muscles, while the fascia 

 lata of the thigh is attached to it below. Near its medial end some of its fibres pass 

 inward to be attached to the ilio-pectineal line of the pubis, forming a horizontal trian- 

 gular sheet whose free concave lateral border forms the medial boundary of \^\^ femo- 

 ral ri?ig (annulus femoralis) through v/hich the femoral hernias make their exit from 

 the pelvis. This reflection (Fig. 531 ) is the ligament of Gimbernat (ligamentum 

 lacunare). Furthermore, a sheet of fibres, variable in its development and termed the 

 tri angular fascia (ligamentum inguinale retlexum), or ligament of Colles (Fig. 1485), 

 is reflected upward and medially from the inner portions of Poupart's and Gimbernat' s 

 ligaments in front of the lower medial portions of the aponeuroses of the internal 

 oblique and transversalis muscles to the anterior layer of the sheath of the rectus. 



The Inguinal Canal. — At an early stage in the development of the foetus an 

 outpouching of the lower part of the abdominal wall occurs on each side to form the 

 genital swellings, which later become the scrotum in the male and the labia majora 



Transversalis muscle 



Fig. 529. 



A 



Transversalis fascia 



Peri- Division of aponeurosis of internal oblique 



toneum / Posterior shealh , — Rectus- 



External oblique 



Internal oblique^ — ~y-~~-~~./-. 



Skin / 



Aponeurosis of internal oblique 



Linea alba 



/ Anterior sheath of rectus 

 Superficial fascia 



.Aponeurosis of external oblique 



Transversalis muscle 

 Internal obi 



External 

 oblique 



Superficial fascia 



Transversalis fascia 



Peritoneum Rectus Linea alba 



: fusion / / -^ / 



Rectus 





Aponeurosis of external oblique Anterior sheath of rectus 



Diagrams showing constitution of sheath of rectus muscle. A, in upper three-fourths; B, in lower fourth. 



in the female. The points at which the outpouchings occur are those at which the 

 lower ends of a ligament descending from the primitive kidneys (mesonephri) are 

 attached to the abdominal wall, and these ligaments, consequently, are carried through 

 the length of the outpouching beneath its peritoneal lining to attach to the walls of 

 the scrotum or the labia. In the female the ligaments become in part the round 

 ligaments of the uterus, but in the male the relations of the outpouchings become 

 more complicated. Owing to the descent into them of the testes (page 2040), the 

 ligaments are drawn completely into the pouch, forming the gubernacula of the testes, 

 while the vasa deferentia and the vessels and nerves of the testes are also carried 

 Into the pouch, uniting to form the spermatic cord. There are, consequently, pass- 

 ing from the abdominal cavity into each pouch, in the female the round ligaments of 

 the uterus and in the male the spermatic cord. 



At first, and in the male for a considerable time after birth, the communication of 

 the pouch with the abdominal cavity is widely open ; but later, in the upper part of the 

 pouch in the male and throughout its entire length in the female, the lumen becomes 

 reduced, and finally is completely obliterated by the union of its walls to the sper- 

 matic cord or the round ligament, its lower portion persisting in the male as the space 

 which exists between the visceral and parietal layers of the tunica vaginalis testis. 



