Chap. 12.] Abdominal Mufcles. 161 



formed by ; a mufcle, which from its fituation and the 

 direction of its fibres is called the obliquus defcendens 

 externus. This mufcle rifes by as many heads from 

 eight or nine of the loweft ribs ; its notches" always mix 

 with thofe of the ferratus major anticus, and generally 

 adhere to the pectoralis major, intercoftals, and latirfi- 

 mus dorfi. It proceeds obliquely downwards and for- 

 wards, and is attached partly to 'the linea alba and 

 partly to the fpine of the ileum. Its tendinous fub- 

 ftance, which forms part of the linea alba, divides be- 

 low into two columns, which leave between them a 

 flit named the ring of the abdomen j of thefe columns 

 the inferior is inferted into the os pubis of the fame fide, 

 the fuperior decurTates its fellow, and paries over to be 

 inferted into the os pubis of the other fide. That part 

 of the external oblique mufcle, which is connected with 

 the fpine of the ileum, is ftretched from the anterior 

 fpinous procefs of that bone towards the os pubis, 

 forming what is called Poupart's or Fallopius's liga- 

 ment. This tendon is united with the ftrong tendi- 

 nous expanfion of the thigh, called fafcia lata, which 

 involves and meaths the mufcles of the thigh, and, pro- 

 ceeding to the kg, performs there the fame office. 



The opening, called the ring of the abdomen, formed 

 by the tendons of this mufcle, gives paffage to the 

 fpermatic veffels in men, and the round ligaments of 

 the uterus in women. The contents of the abdomen, 

 getting through this opening, form the inguinal hernia* 

 Under Poupart's ligament pafs the great veffHs of the 

 thigh, and this is the feat of the crural or femoral her- 

 nia. This mufcle affifts in the exclufion of the fasces 

 and urinej and in expiration, and bends the body for- 

 wards. 



The fecond layer is formed by the obliquus afcen- 

 dens internus. This mufcle ariies from the fpinous 

 and tranfverfe procefles of the three uppermpft lumbar 



VOL, III. M vertebrae, 



