l6 MUSCLES OF THE ABDOMEN 



3. The Internal Oblique Muscle arises from the 

 crest of the iHum, from Poujjart's ligament, and 

 from the aponeurosis of the transversalis muscle 

 anterior to the ilium ; its fibres pass obliquely inward 

 and anferiorly to end in a thin aponeurosis which meets 

 its fellow in the mid-line, and lies immediately below 

 that of the external oblique, the two being separated 

 with some difficulty. 



4. The Rectus Abdominis Muscle is a straight 

 band of fibres arising anteriorly from the sternum 

 and the cartilaginous portions of the posterior ribs, 

 and inserted at the symphysis pubis. Several zigzag 

 lines of fibrous tissue pass transversely across the band 

 of fibres in their course, making it in reality a poly- 

 gastric muscle. 



5. The Transversalis Abdominis arises by fleshy 

 slips from the under surface of the posterior ribs 

 and from the region of the lumbar vertebrae ; the 

 fibres pass transversely inward, and end in a thin 

 aponeurosis lying beneath the rectus abdominis. 



Dissect off very carefully the 1-ectiis abdominis and 

 the transversalis ; a thin 7nembrane, the peritoneum, 

 will be exposed covering over the abdominal organs. 



THE ABDOMINAL VISCERA. 



After removal of the peritoneum the abdominal 

 viscera are exposed in situ. The intestines are con- 

 cealed by a special fold of the peritoneum, the great 

 omentum, which hangs down from the stomach. The 

 omentum is loaded with fat, and if held up against 

 the light it will be found to be penetrated by a num- 

 ber of minute holes. 



