MALE PROCEDURE
(home)
This is the procedure for the male, for female donor instructions select female instructions
PROCEDURE
1. PRE-WORK
(before lab) review the pelvic
bony landmarks.
(Figure401)
(Netter334)
(Netter337)
Lumbar and sacral vertebra - observe how sharply posterior the sacrum is oriented relative to the lumbar vertebra and that the sacrum consists of multiple vertebrae fused together with remnants of intervertebral disks often visible.
Coccyx - The coccyx is the final segment of the vertebral column articulated to the end of the sacrum.
Sacral promontory - The most anterosuperior ridge of the sacrum is sharply angled and marks the border of the pelvic inlet.
Pubic symphysis - Anteriorly, observe the pubic symphysis at the midline.
Pelvic inlet (or pelvic brim) - The pelvic inlet is an imaginary planar line/sheet between the sacral promontory and the upper margin of the pubic symphysis. Laterally, while not visible with the organs in place, the line passes along the inferior edge of the iliac fossa.
The pelvic inlet defines the boundary of the lesser pelvis (also called the 'true pelvis') inferior to the inlet. The greater pelvis (also called 'false pelvis') consists of the area above the pelvic inlet enclosed by the superior edges of the ilia bone. Primarily this area holds the ileum and sigmoid colon.
2. Using moist paper towels clean any excess fluid or debris from the surface of the peritoneum in the pelvic cavity.
3. Observe the pelvic organs and their position relative to
the pelvic bony architecture.
(Figure402) (Netter348)
(Netter349)
Urinary bladder - Immediately posterior to the pubic symphysis is the bisected urinary bladder. Typically, fluid content has emptied and the bladder is in a completely relaxed state flattened against the anterior wall. The superior and lateral edges of the bladder are practically invisible due to this flattening.
Rectum - Anterior to the sacrum/coccyx will be the rectum. Depending on where your viscera removal cut was made there may be a small length of colon still connected to the rectum. The rectum 'start' approximately the level of the sacral promontory (reference sources vary in the anatomic definition of the start of the rectum, thus it is approximate).
Prostate - The prostate is the dense 'lump' of tissue immediately inferior to the bladder approximately at the level of a line between the pubic symphysis and coccyx. This is a subperitoneal organ and thus too inferior to palpate as you follow the peritoneum surface.
4. Trace the peritoneum from the anterior wall across to
the posterior wall of the abdomen as it 'drapes' over the pelvic organs forming
several spaces/grooves.
(Figure402) (Netter348)
(Netter349)
Begin by sliding fingers down the inner wall of the anterior abdominal wall and across onto the superior surface of the bladder. Due to collapse of the bladder, the demarcation between anterior abdominal wall and bladder lacks a distinct groove.
Supravesical fossa - In the living, contents of the bladder result in the superior surface being more horizontal or bulged. The reflection of the peritoneum off the anterior abdominal wall onto the surface of the bladder forms the small supravesical fossa (space) anterosuperior to the bladder.
Rectovesical fossa (or pouch) - Follow the peritoneum across the bladder where it dips inferiorly before reflecting superiorly up onto the rectum. The space formed by the inferior to superior reflection of peritoneum from the bladder to rectum is the rectovesical fossa.
5. Place fingers on the posterior surface of
the bladder and slide your fingers laterally to each side of the bladder, in the
donor the bladder is fully collapsed and the exact lateral extend difficult to
determine.
(Figure402) (Netter348)
(Netter349)
Paravesical fossa - In the living the bladder is expanded posteriorly as well as superiorly, resulting in a groove along each lateral side of the bladder. This is referred to as 'para' meaning 'beside'.
6. Place your fingers on the anterior
surface of the rectum and slide your fingers laterally to each side of the
rectum and the sigmoid colon.
(Figure402) (Netter348)
(Netter349)
Pararectal fossa - The peritoneum sheet reflects off the rectum onto the posterior wall of the sacrum forming the grooves of the pararectal fossa. This will vary in distinctness depending on the distension state of the rectum.
Sigmoid mesocolon - Posteriorly and superiorly from the rectum, the peritoneum forms the sigmoid mesocolon (examined previously in the abdominal viscera lab and most likely removed during that lab).
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. Return to the aorta where you had identified the
testicular arteries in the previous labs and follow the testicular artery inferiorly
all the way to where it exits at the deep inguinal ring.
(Netter348)
(Netter383)
Recall, in males the specific term for the generic gonadal artery is the testicular artery.
8. At the deep inguinal ring blunt dissect the peritoneum
away from the region of the deep ring working inferomedial to find
the ductus deferens as it emerges from the deep ring.
(Netter348)
9. Using spreading motions with scissors follow the ductus deferens
as it courses from the deep inguinal ring past the inferior epigastric vessels before crossing
anterior
(over) the iliac vessels into the pelvis.
(Netter348)
10. Continue to follow the ductus deferens as it descends along the lateral pelvic walls
until it crosses into contact with the posterior side of the bladder.
(Figure403)
(Netter348)
The stopping point need only be approximate on the posterior side of the bladder as we will examine this area in detail in other courses.
11. Return to the ureters, identified in the previous
sessions and follow them to the edge of the pelvic inlet where you had
previously dissected.
(Netter348)
(Netter383)
The ureter passes posterior to (under) the gonadal vessels.
The ureter is a critical structure for gynecological surgery. Ureteral injury is a serious complication associated with high post-surgery morbidity. The ureter has distinct anatomic associations with reproductive organ structures that help the gynecological surgeon determine where they are.
12. Using spreading motions with scissors free the
ureter from the overlying peritoneum and follow the ureter over the pelvic inlet
into the pelvis.
(Netter348)
(Netter383)
The ureter passes anterior (over) the iliac vessels.
13. Return to the infra-renal section of the aorta and
follow the aorta inferiorly to the bifurcation into the left and right common
iliac arteries approximately L4.
(Netter383)
(Netter266)
This segment of the aorta inferior to the renal arteries and superior the bifurcation is the most likely area for aneurysms to develop.
Numerous mesh like arrangements of nerve fibers of the superior hypogastric plexus will be spread out over the aorta and inferior vena cava in this region that were observed in the previous lab.
The superior hypogastric plexus receives mainly lumbar splanchnic nerves (sympathetic) that emerged from the sympathetic chain in the lumbar region. The inferior hypogastric plexus deeper in the pelvis receives sacral splanchnic (sympathetic) from the continuation of the sympathetic chain in the pelvic region and pelvic splanchnic (parasympathetic) nerves emerging from S2-4.
14. Follow the inferior vena cava from the renal arteries
to the bifurcation into the left and right common iliac veins.
(Netter383)
(Netter266)
15. Remove peritoneum from the common iliac artery and vein
on both sides following those vessels to their branch into the internal and
external iliac vessels.
(Netter383)
(Netter266)
Ensure you have identified the gonadal vessels and ureter so as to avoid damaging those as you expose the iliac vasculature.
The common and external iliac vessels course along the pelvic brim. The internal iliac vessels will 'dive' inferoposterior into the pelvis. Only expose peritoneum sufficiently to observe the branch as we will not be dissecting all the internal iliac vessel branches.
16. Continue to follow the external iliac artery lateral
and inferior to where it passes posterior to the inguinal ligament.
(Netter383)
(Netter266)
You may be able to observe the branching of the inferior epigastric vessels which occurs just prior to the external iliac vessels passing under the inguinal ligament.
As the vessel passes under the inguinal ligament the name changes to the common femoral vessels. Following these further will be part of the "Skin, Bones and Musculature" course in MS2 so stop your dissection as the vessels reach the inguinal ligament.
17. Examine the male external genitalia organization.
(Netter333)
(Photo4026)
Body (shaft) of the penis - The primary phallic shaft formed by three columns of erectile tissue (the corpus spongiosum and the paired corpora cavernosa).
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, 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 tissue.
Opening of the urethra - The urethral opening is located at the tip of the glans penis.
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.
18. Return to the superficial inguinal ring and identify the spermatic cord
emerging from the superficial inguinal ring coursing inferiorly towards the
scrotum.
(Figure437) (Netter369)
The spermatic cord contains the testicular artery, venous return the ductus deferens, small nerves and lymphatic vessels.
Note, the membranous superficial fascia of the abdomen (Scarpa's fascia) is continuous with the membranous superficial fascia of the superficial perineal pouch (Colles' fascia) making the scrotum and penile coverings. This is the same layer with just a name change denoting the different region.
Laterally the membranous superficial fascia (Colles') 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 membranous superficial fascia (Colles') forms a fully enclosed compartment, the superficial perineal pouch, which contains the male external reproductive organs (penis, testes, and associated structures). (Figure442)
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.
SWAP POINT #2: 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.
CHECKLIST
Return to the main pelvis page HERE for the combined male/female checklist