MUSCLES OF THE ABDOMEN. 387 



muscle, in general, decussate the fibres of the external oblique, 

 all of them do not; for the lower are brought gradually to pur- 

 sue the same direction towards the symphysis of the pubes. 



Near the Linea Semilunaris, the muscular fibres cease, and 

 the tendon begins. 



It is inserted, by condensed fibrous cellular membrane, into 

 the cartilages of the seventh, eighth, and ninth ribs; and by 

 flesh into the tenth, eleventh, and twelfth. It is inserted also, 

 membranous, into the side of the ensiform cartilage, its whole 

 length; and into the linea alba, from the sternum to the pubes. 



The tendon of this muscle divides into two laminae, which 

 enclose the rectus muscle, and thereby form a sheath for it, 

 imperfect, however, at the lower posterior part near the pubes. 



Its use is the same as that of the External Oblique.* 



3. The Transversalis Abdominis, 



Arises from the transverse processes of the last dorsal, of the 

 four upper lumbar vertebra, and from the back part of the 

 crista of the ilium by the Fascia Lumborum. It also arises, 

 fleshy, from the anterior two-thirds of the spine of the ilium, 

 and from the exterior half of Poupart's ligament; and tendinous 

 and fleshy alternately, from the inferior margin of the thorax, 

 formed by the cartilages of the six or seven inferior ribs, at 

 their inner surfaces, where they are concerned in the origin of 

 the diaphragm. 



The fleshy part of this muscle occupies about one-third of 

 its extent. It is inserted into the side of the ensiform cartilage; 

 filling up the vacancy between it and the cartilages of the sixth 

 and seventh ribs; and into the linea alba, from the extremity of 

 the sternum to the pubes. The Transversalis and the Internal 

 Oblique also form below a common tendon, which is inserted 

 for an inch into the crista of the pubes, behind the insertion of 

 Gimbernat's Ligament; into the spine of the pubes; and into 

 that part of the body of the pubes which forms the lower pos- 

 terior boundary of the external abdominal ring. Just above 

 this insertion the common tendon alluded to splits into two la- 



* Varieties. It is sometimes defective at its lower part, and on other occa- 

 sions redundant. 



