PROCEDURE
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This is the procedure for the male, for female donor instructions select female instructions

1. Turn your donor to the supine position and move the lower limbs to the sides to allow view of the external genitalia.

2. Examine the male external genitalia organization.
    (Netter333) (Photo4026)

Body (shaft) of the penis - The primary muscular shaft formed by three columns of erectile tissue (corpus spongiosum and paired corpora cavernosa structures which we will examine later in the lab).

Under the skin the corpus spongiosum anchors to the perineal membrane at the midline while the corpora cavernosa 'split' at the base of the penis and run extend under the skin along the perineum parallel to the inferior pubic rami nearly the full length of the rami.

Foreskin - A double-layered fold of skin that covers and protects the glans penis. The outer surface is typical thin skin which transitions to a mucus membrane surface on the inner side of the foreskin.

The foreskin in some males may be absent as a result of surgical removal (circumcision) during infancy or later, typically performed due to familial or cultural choice by parents. 

Glans penis - A bulbous structure at the end of the penis partially or completely covered by foreskin (when present). The glans penis is an extension/cap of the corpus spongiosum erectile tissue.

Opening of the urethra - The urethral opening is located at the tip of the glans penis.

The urethral opening is the entry point for a Foley catheter, to access the bladder for drainage.

Scrotum - The scrotum is a dual chambered protuberance of skin, fascia, and muscle tissue that are contiguous extensions of the superficial abdominal wall layers. The scrotum is separated by a septum into a left and right chamber containing respectively the left and right testis.

The male superficial perineal pouch is a fully enclosed compartment containing the external genitalia (penis, testes, and associated structures).

3. Starting at the superficial inguinal ring push your finger inferiorly along the spermatic cord to lift the skin and superficial fascia (both sides of the donor, unless otherwise stated the procedures below are bilateral). 

4. Using scissors cut through the skin and superficial fascia anterior to the spermatic cord working your way inferiorly across the anterior surface of the scrotum to expose the testes.
    (Figure437) (Figure442) (Netter369) (Photo4043)

Note that the membranous superficial fascia of the abdomen (Scarpa's fascia) is continuous with the membranous superficial fascia of the superficial perineal pouch (Colles' fascia). This is the same layer with a name change denoting the different regions. 

Laterally, the fascia firmly attaches along the margins of the pubic rami, extends around the shaft of the penis, and continues posteriorly to join the inferior fascia of the urogenital diaphragm. Thus, the fascia forms a fully enclosed compartment, the superficial perineal pouch, which contains the male superficial genitalia.

The enclosed superficial perineal pouch is clinically important as bleeding or urine flow from testicular/penile injury will fill this space extending up the abdominal wall between the fascia layers, but cannot extend onto the thighs or anal triangle.

The fatty superficial fascia of the abdomen (Camper's) is also continuous inferiorly between the skin and membranous fascia as a thin fat-free layer of smooth muscle fibers. Across the superficial perineal pouch it is called the dartos muscle. When cold, contraction of the dartos muscle fibers wrinkles the skin and assists drawing the testes close to the body to maintain temperature. These fibers are not visible to the eye.

5. Push your fingers into the scrotum on each side and feel for the scrotal septum separating the sac into left and right chambers.
    (Figure437)

You may also feel a small ligament, the scrotal ligament, which connects the inferior pole of the testes to the scrotum.

The scrotal ligament is the embryological remnant of the gubernaculum which functioned as a 'string' to pull the testes out of the body during development.

6. Push a probe between the testis and the scrotal septum to pull the testes anteriorly out of the scrotum severing the sctotal ligament leaving the testis attached only by the spermatic cord.
    (Photo4044)

SWAP POINT #1: At this point, swap with your pre-identified table (Laboratory Swap Map). containing a donor of the opposite sex and go through the steps on the appropriate instruction set until you reach the swap point in those instructions. Then return to your donor to continue steps below.

7. With a sharp probe penetrate the outer covering of the testes on the anterolateral surface and with scissors open the sac along the entire lateral surface to expose the testis and epididymis.
    (Figure437) (Netter369) (Photo4045)

Each testis is covered by the tunica vaginalis, a serous sac consisting of a visceral and parietal layer with a thin film of fluid between. As you open this sac observe how the testes can 'slide' within the space formed by this sac.

Observe that the epididymis lies along the posterior side of the testes. There is typically a distinct shallow groove between the testes and epididymis assisting identification.

8. Blunt dissect along the epididymis to the inferior pole of the testis, where the epididymis makes a 180 degree turn to return in the superior direction.
    (Netter369) (Netter372) (Photo4046)

The region of the epididymis connected to the superior pole of the testis is the head, the region you followed inferiorly is the body, and the turn to a superior direction is the tail. The tail becomes continuous with the ductus deferens which will be examined below.

9. With a sharp probe or scissors follow the tail of the epididymis superiorly where it becomes the tubular ductus deferens coursing within the core of the spermatic cord.
    (Figure437) (Netter369) (Photo4047)

10. Dissect several inches along the spermatic cord to examine the features of the ductus deferens.
    (Netter369) (Photo4047)

The ductus deferens, when rolled between the fingers, feels like a hard cord. The region you are examining is the most common location for removal of part of the ductus deferens in vasectomy. Thus, if your individual has had a vasectomy, there may no longer be a distinct ductus deferens to follow into the spermatic cord. 

 The testicular artery has a tortuous (coiled/looped) path and has a smaller diameter than the ductus deferens. Recall that the testicular artery arose from the abdominal aorta and traveled to the testes via the inguinal ring. If intact, you can observe in the abdominal cavity the course from the inguinal ring as far as its origin at the abdominal aorta.

Surrounding the testicular artery and ductus deferens is a dense network of pampiniform veins that can be difficult to identify in a donor. The heavily intertwined venous plexus drains into the testicular vein and back to the inferior vena cava via the inguinal ring.

11. With a scalpel bisect the testes along the anterior mid-sagittal plane from the superior to inferior pole.
    (Figure439) (Netter372) (Photo4048)

12. Using the epididymis as a hinge open the hemisected testis to examine the internal structure.
    (Figure439) (Netter372) (Photo4048)

Deep to the visceral layer of the tunica vaginalis is the dense connective tissue capsule of the testis, the tunica albuginea which gives rise to septa of connective tissue dividing the testis into lobules.

Observe the highly coiled seminiferous tubules that fill the space between the septa of the testicular lobules. If the testis is well preserved you may be able to 'unravel' some of the tubular coils.

The seminiferous tubules empty into the rete testis in the thickened hilar stroma just inferior to the exit ducts to the epididymis. 

When finished examining the testis, leave it attached via the spermatic cord and reflected away from the urogenital region so you can dissect deeper structures without damaging the testis/spermatic cord.

13. Transect the penis approximately half way along its length leaving the skin on one side intact to serve as a 'hinge' and examine the cut surface to observe the following.
    (Figure441) (Figure442) (Netter363) (Photo4049)

Corpus spongiosum - On the ventral side of the penis is a single column of erectile tissue (cut in cross section by transecting the penis).

Urethra - In the middle of the corpus spongiosum is the urethra.

Corpora cavernosa - Laterally are the paired corpora cavernosa columns of erectile tissues (also cut in cross section by transecting the penis). In the middle of the corpora cavernosa tissues is the deep arteries of the penis, which provides blood during erection. This artery may not be apparent depending on the preservation state of the donor. 

Tunica albuginea - The erectile tissue shafts within the penis are surrounded by a strong connective tissue wrapping around each column of erectile tissue. The tunica albuginea fuses in the spaces between the corpora cavernosa and corpus spongiosum to form a septum separating the erectile tissue columns. 

Dorsal nerve, artery, and vein of the penis - At the dorsal side of the penis at the midline are paired dorsal arteries of the penis, paired dorsal nerves of the penis, and a single dorsal vein of the penis. These are not always visible with the naked eye in a cadaver, but you may with a magnifier (special tools box) be able to see the cross sections of the dorsal vessels.

Deep fascia of the penis (penile fascia) - The shaft of the penis is covered by a fascia sheath (Buck's fascia). The superficial membranous fascia of the superficial perineal pouch fuses to the penile fascia near the base of the penis, thus the superficial perineal pouch does not extend along the full length of the penile shaft.

The penis is also stabilized by a suspensory ligament spanning from teh base of the dorsal penis to the pubic ramus, providing support for the penis when erect. There is a suspensory ligament of the clitoris in female, although the shorter clitoral elective tissue does not require extensive structural support.

SWAP POINT: At this point, swap with your pre-identified table (Laboratory Swap Map) containing a donor of the opposite sex and review through the steps on the appropriate instruction set until you reach the swap point in those instructions (note the dissection will have been performed by the other table so you will be examining the exposed structures at their table). Then return to your donor to continue steps below.

PROCEDURE - PUDENDAL

14. Turn the donor over to prone position

15. Partially spread the donor's lower extremities as this will make access into the anal triangle easier.
    (Figure549)

Placing the wood block between the legs may assist in keeping the donor's lower extremities spread while working in this region.

The anal triangle is an region formed by imaginary lines from the left and right ischial tuberosity and the midline coccyx. The anus, ischiorectal fat, and inferior rectal branches of the pudendal neurovascular bundle are the important structures in the region.

16. Identify the sacrotuberous ligament between the hard point of the ischial tuberosity and the edge of the sacrum.
    (Figure504) (Netter493) (Photo5048)

Pressing your fingers onto the ligament you will feel a slight 'bounce' to the tight ligament which can give a guide to where the ligament is positioned.

The triangularly shaped sacrotuberous ligament is attached to the ischial tuberosity and spans to the sacrum. Only limited movement is possible between these bony points. The ligament primarily serves to stabilize the sacroiliac joint and as a shock absorber during locomotion.

17. Clean any remaining fascia from the posterior surface of the sacrotuberous ligament to define the borders of the ligament.
    (Figure504) (Netter493) (Photo5048)

The pudendal nerve courses deep to the sacrotuberous ligament, which must be severed in order to view the nerve.

18. Insert a blunt probe just deep to the sacrotuberous ligament passing from superior to inferior.
    (Photo4020)

19. Using the blunt probe as a guide, transect the sacrotuberous ligament in the middle.
    (Photo4031)

Transecting the sacrotuberous ligament exposes the area of the lesser sciatic foramen where we will observe the pudendal branches.

20. Reflect the cut ends of the ligament laterally and medially exposing the fascia below.

21. Blunt dissect into the fascia below the sacrotuberous ligament to find the pudendal neurovascular bundle.
    (Figure503) (Netter493) (Photo4021)

The pudendal neurovascular bundle (nerve, artery and vein) exits the pelvis through the greater sciatic foramen, inferior to the piriformis muscle and medial to the sciatic nerve. 

The pudendal neurovascular bundle travels deep to the sacrotuberous ligament and superficial to the sacrospinous ligament (i.e. through the lesser sciatic foramen you opened by cutting the sacrotuberous ligament).

The pudendal neurovascular bundle bifurcates into rectal (to the anus) and perineal (to the perineum) branches as it passes out from under the sacrotuberous ligament. 

We will not dissect the nerve further than the nerve's passage deep to the sacrotuberous ligament. This location, as the nerve courses towards the perineum/anal regions, is a common target for local anesthesia for OBGYN procedures.

The bifurcation of the nerve can occur prior to emerging from the greater sciatic foramen, in which case you will see two neurovascular bundles passing deep to the sacrotuberous ligament (one turns to the anus and a second towards the perineum).

The perineal branch continues anteriorly to the medial side of the ischial tuberosity and then to the perineum. The location just distal to the ischial tuberosity is the approximate target for injecting anesthesia in a pudendal nerve block. Most commonly, the needle approach is from the inferior aspect using the ischial spine as a palpable landmark. The needle is inserted parallel to the plane of the urogenital triangle in order to anesthetize the main branch of the pudendal nerve innervating the urogenital region. (Figure444)

22. Place the excised reproductive organs into the biohazard bag with the heart/lungs in the organ box when complete for the day.

CHECKLIST

Return to the main perineum page HERE for the combined male/female checklist.