VH Dissector: Male Perineum

Begin with the male skeleton

Add the lateral wall muscles and ligaments.

Using the Highlight tool, identify the following muscles: 

• Piriformis muscle

• Obturator internus muscle

• Sacrotuberous ligament

Note that the sacrospinous ligament was not identified in this cadaver.

Add and identify the levator ani and coccygeus.

Add the bulb of the penis and the bulbospongiosis muscle that overlies it.

Add the left and right crus of the penis and the ischiocavernous muscles that cover them

Add the superficial transverse perineal muscles (not well seen here)

Add the corpus spongiosum.

Add the corpus cavernosum.

Add the glans penis.

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. Note that the left pudendal is not entirely visible in the model.

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 are nicely seen in the model, as are the arteries related to the penis.

Move the cross-section up and down to visualize the extent of the fat-filled ischioanal fossa and its relationship to the obturator internus and levator ani.

Now create an axial section view without the reconstruction that coincides with the level seen in the CT scan below.  Click through the Axial CT stack and try to identify each annotated structure.  Structures you should definitely know are indicated in yellow after you click for the answer.    

Use the highlight tool to identify structures in the cadaver coronal section, then try to identify the same in the CT scan.  

Now create a coronal section view without the reconstruction that coincides with the level seen in the CT scan below.  Click through the CT stack and try to identify each annotated structure.  Structures you should definitely know are indicated in yellow after you click for the answer.    

Use the highlight tool to identify structures in the cadaver coronal section, then try to identify the same in the CT scan.