In this section we will start with the model that we built of the pelvic floor ligaments and musculature, then build the components of the female perineum, first focusing on the Urogenital Triangle, and then the Anal Triangle.
Begin where we ended the ligament and muscle build from the last set up labs.
From this view we can review the landmarks we will use to visualize our urogenital and anal triangles of the perineum.
Highlight the bones and ligaments of the pelvis to make it easier to appreciate the outline of the perineum. Imagine a line connecting between the two ischial tuberosities dividing the diamond shaped opening created by the bones and ligaments into an anterior (urogenital) and posterior (anal) triangle.
Add the perineal body
Add the superficial transverse perineal muscle
Add the vaginal orifice
Add the urethral sphincter
Add the corpus cavernosum of the clitoris
Add the fascia of clitoris. Unfortunately, the bulb of the vestibule and greater vestibular gland are not visible on this cadaver. Reference the drawing for the location of these structures.
On top of this membrane sits the erectile tissues of the urogenital triangle.
The erectile tissues are covered by ischiocavernosus and bulbospongiosus muscles as follows:
Add the ischiocavernosus muscles which cover the corpus cavernosi. The corpus cavernosi joins at the midline to form the glans clitoris.
Add the bulbospongiosus muscles which cover and surround the remaining components of the vestibule.
Note that the urethral orifice is just posterior to the glans clitoris.
Add the external anal sphincter.
Now we will focus on the neurovasculature of the anal triangle, specifically the structures that pass through the ischioanal fossa.
Add the pudendal nerve and trace its path from the sacrum to the pelvic diaphragm. You will have to rotate the pelvis in order to see its origin and where it ends in the perineum.
We have also added to the model the entire sacral plexus so you can see the origin of the pudendal nerve from S2-S4 and its passage through the greater sciatic foramen to leave the pelvis, and entrance into the lesser sciatic foramen in order to reach the ischioanal fossa. In this particular individual the pudendal nerve passes underneath both sacrotuberous and sacrospinous ligaments, whereas its usual pathway is between the two.
Add the internal pudendal artery and trace its path from its origin from the internal iliac artery to the pelvic diaphragm. Again, you will have to rotate the pelvis in order to see its origin and where it ends in the perineum.
The inferior rectal branches of the internal pudendal artery cannot be seen in the model, but realize that these supply the lower anal canal below the pectineal line, and the anal sphincter.
VH Dissector steps modified for Drexel Dissector by Dr. Haviva Goldman from original website activity created by Jeffrey Fahl, MD, Kyle Petersen, PhD, Richard Drake, PhD, Alesha Petitt, MA, Claira Ralston, MS and Kim Price, MA and modified by Jeffrey Fahl, MD, Michael Smith, PhD, Albany Medical College.