3. The serratus posterior superior (p. 148, and Fig. 73, _l_). Transect
this at about the middle of the muscle-bundles, and reflect it in both
directions.
4. The serratus posterior inferior (p. 148, and Fig. 73, _n_). Transect
and reflect as in the last.
5. The external oblique (p. 153, and Fig. 68, _p_). Transect it by an
incision parallel to its tendon of origin and about an inch from it, and
reflect in both directions.
6. The internal oblique (p. 154, and Fig. 73, _o_). Transect and
reflect as above.
7. The transversus (p. 155, and Fig. 69, _l_). Requires no further
dissection.
8. The rectus abdominis (p. 155, and Fig. 73, _k_). Open its sheath by
a longitudinal incision near the linea alba.
9. The external intercostals (p. 150, and Fig. 73, _m_; Fig. 69, _i_).
To see these, remove the origins of the levator scapulæ and serratus
anterior; also the serratus posterior superior.
10. The internal intercostals (p. 151, and Fig. 69, _k_). To uncover
these, remove the external intercostals from between two or three pairs
of ribs.
11. The transversus thoracis (p. 151). To see this muscle, which lies on
the inner surface of the thoracic wall, it is necessary to cut through
the ribs on one side one or two inches from the sternum, and open the
thorax. The muscle can then be observed directly.
(The levatores costarum will be dissected later.)
VI. MUSCLES ON THE VENTRAL SIDE OF THE VERTEBRAL COLUMN IN THE NECK
REGION (Fig. 72).
Clean the surface of these muscles, removing pharynx, larynx, œsophagus,
and trachea, if this has not been done.