16 MUSCLES OF THE ABDOMEN 
3. The Internal Oblique Muscle arises from the 
crest of the ilium, from Poupart’s ligament, and 
from the aponeurosis of the transversalis muscle 
anterior to the ilium; its fibres pass obliquely inward 
and anteriorly 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 
ships irom “the under ‘surface of the sposterior ribs 
and, from the region of the’ lumbar vertebrze: the 
fibres pass transversely inward, and end in a thin 
aponeurosis lying beneath the rectus abdominis. 
Dissect off very carefully the rectus abdominis and 
the transversalis,; a thin membrane, 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 imtestines. areccon- 
cealed by a special fold of the peritoneum, ¢he 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. 
