The dissection of the perineum is first approached posteriorly (anal triangle) and then inferiorly (urogenital triangle) by putting the cadaver in the lithotomy position.

Basic concepts:
You may wish to review the basic concepts for the upper limb at this time. The link opens a new window which you will need to close to return to this page.

Specific Learning Objectives:

1. Know the bony/ligament components and understand sexual differences in these components.
2. Understand how the greater and lesser ischiadic foramina are formed.
3. Know the branches of the lumbar-sacral plexus and the segmental contributions to each (e.g., pudendal - S2,3,4).
4. Understand the relationships of viscera. Know the sexual differences.
5. Know that the perineum is divided into anal and GU triangles (regions).
6. Learn the relationships of structures in the superficial and deep pouches.
7. Visualize the parts of the urethra. What are sexual differences.
8. Understand how different fascial layers (e.g., Colle's fascia) contribute to the compartmentalization of the region.
9. Understand the importance of the pectinate line with respect to the vasculature and lymphatic drainage of the rectum and anal canal.
10. Know the contents of the superficial and deep perineal pouches. What are the sexual differences.
11. Learn the nerve supply and vascularization of the perineum.
12. Identify anatomic structures in radiographic studies including X-ray, CT scans and MRI films.

Difficult parts of the dissection:

1. Dissecting the anal triangle is difficult only because it requires removing lots of fat. You must remain oriented which requires palpation of the bony boundaries (i.e., ischial tuberosity, sacrum, sacrotuberous ligament, etc). Use a rolled paper towel as a tampon inserted into the anal canal to provide support and prevent spillage. See Step 1.
2. Demonstrating structures in the urogenital triangle is easier in the male simply because everything is larger. However, you are expected to understand the anatomy in both males and females. Be sure and get around to other dissections.