202 MYOLOGY. 



four anterior digitations are received between the corresponding 

 ones of the serratus magnus ; to the fascia of the latissimus dorsi, 

 and superiorly to the lumber fascia ; to the anterior iliac spine 

 and crest ; to the pubis and prepubian tendon, and inferiorly to 

 the linea alba throughout its whole extent. 



Relation. — Externally with the abdominal tunic ; antero- 

 externally with the pectoralis magnus ; internally with the ribs, 

 cartilages, and intercostals, the internal oblique and the rectus; 

 anteriorly with the serratus magnus. 



Action. — To support and compress the abdominal viscera, and 

 assist in defecation, urination, and parturition. It is also a 

 flexor of the vertebral column, and a muscle of expiration. 



APONEUROSIS OF THE OBLIQUUS EXTERNUS. 



The distribution of this aponeurosis being very singular and 

 important, it merits separate consideration. It stretches from 

 the anterior spine of the ilium to the pubis, answers to the 

 fold of the groin, and marks the division between the trunk 

 and hind extremity. Posteriorly it splits into two layers ; one 

 descends internally over the thigh, forming the crural a^poneurosis; 

 the other is reflected upwards, and enters the abdominal cavity, 

 this fold receiving the name of the crural arch or Powpart's 

 ligament. Near the prepubian tendon, and immediately in 

 front of its division, the aponeurosis is pierced by a large oval 

 aperture, the external abdominal ring, which is the external 

 opening of the inguinal canal. 



Crural AjJoneurosis. 



This descends over the fold of the groin to the patella, and 

 internal surface of the thigh, blending outwardly with the fascia 

 lata, and internally becoming less dense in structure ; it covers 

 the sartorius, part of the gracilis, vastus internus, and the crural 

 vessels as they leave the abdomen. 



Poupart's Ligament. 



The Crural Arch or Poupart's Ligament is a ribbon-shaped 

 reflected portion of the aponeurosis of the external oblique, and is 

 attached by its extremities to the anterior spine of the ilium, and 

 anterior border of the pubis. Anteriorly it forms the posterior 



