Biology 122 Spring, 2008

Laboratory 19

Pelvic Autonomics, Lumbosacral Plexus and Pelvic Musculature

OBJECTIVES

At the end of this lab you should:

1. Know the definitions, origins, cell body locations, synaptic relationships and functional components of the lumbar splanchnic nerves, aortic plexus, superior hypogastric plexus, inferior hypogastric (pelvic) plexus and the pelvic splanchnic nerves.

2. Have a detailed understanding of the significance of extension of the sympathetic chain into the pelvis and the distribution of its postganglionic fibers to the lower limb, pelvic organs and blood vessels.

3. Know the name, course, position and general distribution of the lumbar and sacral (lumbosacral plexus) nerves within the pelvis. These include the iliohypogastric, ilioinguinal, genitofemoral, lateral femoral cutaneous, obturator, femoral, sciatic, superior and inferior gluteal nerves and the pudendal nerve.

4. Know the position of the openings through which the nerves of the lumbosacral plexus, and their accompanying vessels, leave or enter the pelvis. These include the inguinal rings, the obturator canal, the muscular and vascular lacunae, and the superior and inferior sciatic foramina.

5. Understand the position and structural organization of the pelvic diaphragm. These parts include the arcus tendineus (tendinous arch of the levator ani), the coccygeus, iliococcygeus, pubococcygeus and puborectalis muscles. The levator ani muscles should be understood as functional group.

PRELAB PREPARATION

1. Review the osteology of the pelvis (M&D, pp357-368).

2. Study those sections of your textbook that deal with the pelvic cavity, its walls and floor (pp. 368-379), and the pelvic nerves (pp. 379-383).

3. Understand the course, distribution and function of autonomic nerves in the pelvis (see Synopsis of Pelvic Nerves on course website).

4. Review the sections of the chapter on the perineum that cover the UG diaphragm and perineal musculature (p. 441).

5. Study the organization of the lumbosacral plexus. Although you were expected to draw diagrams of the brachial plexus this is not necessary for the lumbosacral plexus. You should, however, know the segmental origin of each of the nerves.