MUSCLES OF THE ABDOMEN. 385 



1. The Obliquus Externus, 



Arises from the eight inferior ribs by muscular and tendinous 

 digitations attached near their anterior extremities. The first 

 head is covered by a slip from the pectoralis major, the five 

 upper heads are interlocked with the origins of the serratus 

 major anticus, and the three inferior with those of the latissi- 

 mus dorsi. The fibres pass obliquely downwards, and termi- 

 nate in a broad thin tendon. This tendon extends over the 

 whole front of the abdomen, from the lower end of the second 

 bone of the sternum to the symphysis of the pubes. 



This muscle is inserted into the whole length- of the linea 

 jilba; into the anterior half or two-thirds of the crista of the ilium, 

 by muscular fibres posteriorly, and tendinous anteriorly; and, 

 from the anterior superior spinous process, the tendon extends 

 to the body and to the symphysis of the pubes, forming thereby 

 the ligament of Poupart, or the Crural Arch. 



In the middle line of the body, the tendons of the three broad 

 muscles, on both sides of the abdomen, unite to form the Linea 

 Alba, which extends from the sternum to the pubes. From 

 two to three inches in the adult, on either side of the linea alba, 

 but more distant from it above than below, is another line, formed 

 by the same tendons, which is the Linea Semilunaris. The 

 navel, which originally was a hole for the passage of the 

 umbilical vessels, and, in the adult, is commonly depressed into 

 a pit, appears in the linea alba as a protuberance composed of 

 a condensed cellular membrane. Just at the navel there is a 

 line crossing the linea alba, and extending from one linea se- 

 milunaris to the other; at the lower end of the Cartilago-Ensi- 

 formis, there is another; and half-way between this and the 

 navel, a third : about half-way between the navel and the pubes 

 is a fourth, but it is generally imperfect. These are the Linear 

 Transversoe, and they are formed foy tendinous matter in the 

 substance of the recti muscles, connecting them to their tendi- 

 nous sheath in front. 



The most interesting insertion of the tendon of the external 

 oblique, is the portion constituting Poupart's ligament, or the 

 Crural Arch. The latter as it gets to the pubes from the ilium, 

 splits so as to leave a hole for the passage of the Spermatic 



VOL. I. 33 



