Chapter V: Muscles of the Wall of the Thorax and of the Abdomen

1. The scalenus (p. 141, and Fig. 73, _f_-_f‴_). To trace its cervical portion, cut the trachea and œsophagus just craniad of the first rib, cut the pharynx and hyoid free from the ventral side of the head and neck, and remove the pharynx, larynx, œsophagus, and trachea (these should be preserved for future study of the larynx).

2. The transversus costarum (p. 150, and Fig. 73, _j_).

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.)