Tips on Muscle Dissection

Abdominal muscles – the external oblique, internal oblique, and transversus abdominus are incomplete muscle layers; none of them cover the entire abdominal wall. The best location to find all three layers together is near the leg, away from the midline. See p. 21 of the FPDG (Fetal Pig Dissection Guide).

Intercostal muscles – like the abdominal muscles the intercostal muscles are incomplete layers; they are not found
at every location between every pair of ribs. They are best found away from the midline. See p. 21 of the FPDG.

Neck muscles – most of the neck muscles can more easily be learned if you know four anatomical landmarks: (1) the sternum; (2) the thyroid cartilage of the larynx (the “Adam’s apple” often visible in the human neck); (3) the hyoid bone; (4) the mastoid process (the bony prominence of the temporal bone which you can feel behind your ear). The sternothyroid muscle, therefore, goes from the sternum to the thyroid cartilage. The sternohyoid, thyrohyoid, and sternomastoid can also be readily identified based on the four landmarks. See p. 23 of the FPDG.

Spinodeltoid muscle – The spinodeltoid muscle is very thin; often is just a connective tissue layer with a few muscle fibers. Because of this, it is often removed as being just superficial fascia. See p. 25 of the FPDG.

Brachioradialis & extensor carpi radialis muscles – these two muscles develop together and share a connective tissue membrane in the fetal pig; consequently they look like a single muscle until separated. To separate them, a blunt probe can be used to find the weak point between them. See p. 23 of the FPDG.

Forelimb muscles – Many dissection manuals incorrectly identify some of the forelimb muscles of the fetal pig. The
extensor carpi radialis (separated from the brachioradialis as described above) is sometimes misidentified as the flexor carpi radialis. Sometimes the antebrachial fascia is identified as a muscle. Many of the muscles have two heads, making identification difficult. See pages 25 and 31 of the FPDG.

Semitendinosus muscle – This muscle, found next to the biceps femoris, looks like a large, shiny tendon from a posterior viewpoint, hence the name semitendinosus. See p. 35 of the FPDG.

---