41. The tarsal muscles (p. 215). The overlying ligaments must be removed
in order to expose the scaphocuneiform.
IX. THE DIAPHRAGM AND THE MUSCLES ON THE VENTRAL SIDE OF THE VERTEBRAL
COLUMN IN THE LUMBAR AND PELVIC REGIONS.
Remove the ventral and lateral walls of the thorax completely, as far
back as the diaphragm,--leaving only a ring attached to the margin of
the diaphragm. Remove the abdominal walls in the same way, as far back
as the pubis, leaving the diaphragm in position. Remove the thoracic
viscera (the heart and lungs may be preserved for future study). Remove
also the abdominal viscera as far back as the beginning of the pelvis,
cutting the large intestine where it passes into the pelvis. The dorsal
wall of the abdominal cavity should be cleared of fat, blood-vessels,
etc., without injury to the crura of the diaphragm.
1. The diaphragm (p. 151, and Fig. 74). Study by transmitted light, to
see the tendons, etc.
2. The psoas minor (p. 139, and Fig. 162, 9, p. 398). Find its tendon
and separate it from the iliopsoas (Fig. 162, 8) as far craniad as this
can be done without tearing the fibres.
3. The iliopsoas (p. 193, and Fig. 162, 8). Find both portions; isolate
them as far as it can be done.
4. The quadratus lumborum (p. 139). Free the lateral edge of the
iliopsoas from the abdominal wall and turn the whole muscle mediad as
far as possible. The bundles of the quadratus lumborum will be found
beneath it, against the transverse processes of the lumbar vertebræ.
With a heavy cartilage-knife separate the two innominate bones along the
pelvic symphysis. This is easily done if the knife is inserted exactly
into the line of junction of the two bones. Divaricate the edges some
distance, so as to make a ventral opening into the pelvic cavity. If
necessary, part of the innominate bone of one side may be removed to
make the opening larger.
Find the thin sheet of fibres forming the levator ani muscle (Fig. 162,
11) at the side of the rectum, attached to the edge of the symphysis.
Carefully free the rectum and urogenital organs from this and remove
them as far as the anus, leaving the levator ani intact.