VH Dissector: Female Perineum

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.

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.