Anatomy - 47 - Male Pelvis

Examination of an elderly man with prostatitis reveals that his seminal colliculus is infected. Which of the following structures is likely to be affected? A. Ducts of the prostate gland B. Prostatic utricle C. Ducts of the bulbourethral glands D. Ejaculatory ducts E. Ducts of the seminal vesicles

D. The ejaculatory ducts sit very near the seminal colliculus (they open on the colliculus).

What are the branches of the posterior branch of the interior iliac artery (male)?

Iliolumbar artery, lateral sacral artery, superior gluteal artery.

What is micturation?

Another name for urination.

Where does the ureter generally cross the iliac artery?

At the division of the iliac artery into the internal and external iliac arteries.

Where does the urethra exit the male bladder?

At the urethral oriface of the inferior part of the bladder.

A 48-year-old football coach undergoes a radical prostatectomy. Following surgery, he is incapable of an erection. Which of the following nerves is most likely damaged during the surgery? A. Sacral splanchnic nerve B. Pelvic splanchnic nerve C. Pudendal nerve D. Dorsal nerve of the penis E. Posterior scrotal nerve

B. Pelvic splanchnic nerve. The pelvic (p for parasympathetic) splanchnic nerve carries the parasympathetic fibers that enable erections.

How is the prostate divided into anatomical lobes?

Based on the position of the urethra and ejaculatory ducts. These lobes are: anterior lobe, posterior lobe, and middle lobe. the middle lobe is between the urethra and the ejaculatory ducts.

A 44-yo man is diagnosed as having a cancerous growth in his testes. Which lymph nodes should be biopsied to determine if the growth is metastatic? A. Superficial inguinal B. Internal iliac C. Lumbar D. Deep inguinal E. Sacral

C. Lumbar. Embryologically, the testicles developed superior to their final location. They descend through the action of the gubernaculum. Because they originally sat superior to their final location, they retain lymph drainage that is superior to much of the rest of the pelvis.

A stab wound immediately superior to the pubic symphysis would likely injure which visceral organ first? A. seminal vesicles B. rectum C. prostate D. bladder E. heart

D. Bladder. The bladder sits immediately behind the pubic symphysis. In individual with some urine within the bladder, the bladder will rise above the pubic symphysis.

True or false: bulbourethral glands and the ejaculatory ducts enter the urethra through the same opening.

False. The bulbourethral glands enter the penis distal to the ejaculatory ducts.

What are the branches of the anterior branch of the interior iliac artery (male)?

Obturator artery, umbilical artery, inferior vesicular artery, internal pudendal artery, middle rectal artery.

Where do the ureters enter the male bladder?

On the posterior surface at the ureteric orifaces.

Which fibers, sympathetic or parasympathetic, carry the afferent fibers that signal a full bladder? How is this significant?

Parasympathetic fibers. It is rare for parasympathetic fibers to carry afferent messages. The parasympathetic message (indicating a full bladder) works in opposition to the sympathetic reflex of keeping the sphinctor closed.

What nerve fibers are most at risk during a prostate surgery?

Pelvic splanchnic nerves. These are parasymphathetic nerves that run very near to the prostate.

What fibers control the internal urethral sphinctor? Are these nerves at risk during prostatectomy? If not, which nerves are at risk?

Symphathetic nerves. These sympathetic nerves run into the penis and surrounding tissues via blood vessels. This is unlike the parasympathetic nerves, which run into the area near the prostate. Cutting the sympathetic nerves would tend to cause urinary incontinence; however, these should remain un-damaged in a prostatectomy. Parasympathetic nerves; however, are at significant risk during prostate surgery. These nerves do not control urinary function. They do, however, contribute to the ability to have an erection and other functions.

Describe the location of the seminal vesicles and Vas Deferens relative to the bladder on the posterior (dorsal) side.

The Vas Deferens and seminal vesicles come from each side of the bladder, and wrap around it, running posteriorly and medially. See the attached (pink tubes and tortuous green tubes).

Describe where the male bladder sits within the pelvis.

The bladder just superior to the pubic symphysis. When the male bladder is empty, it rarely extends above the pubic symphysis/pelvic brim. When the male bladder is full, it often extends into the space above (superior and slightly posterior to) the pubic symphysis and pelvic brim.

Describe the position of the male bladder relative to the prostate and urogenital hiatus.

The bladder sits superior to the prostate. The bladder/prostate sit immediately superior to the urogenital hiatus. In the attached image, the urogenital hiatus is noted with a small, red star.

What are the bulbo-urethral glands (male)? What is their purpose?

The bulbo-urethral glands secrete a salty solution meant to clear the last of the urine out of the urethra prior to ejaculation. For this reason, these glands are located distally (nearer to the tip of the penis) relative to the ejaculatory ducts. The anatomical location of these glands (in the urethra) are important for generating viable ejaculate.

The ductus deferens and the seminal vesicles meet just prior to which duct?

The ejaculatory duct.

Which sphinctor is essential in allowing bladder filling? What nerve type innervate this sphinctor?

The external sphinctor of the bladder. This sphinctor is under the control of both sympathetic and somatic innervation.

What blood vessels run through the lateral umbilical ligament?

The inferior epigastric vessels.

What artery (a branch of the anterior internal iliac) often gives off branches to the prostate?

The inferior vesicular artery.

In which lobe of the prostate do most cancers arise? How does this present symptomatically?

The middle lobe of the prostate is the location for the beginning of most prostate cancers. The middle lobe of the prostate is the superior lobe and is proximal to the bladder. Growth of the middle lobe of the prostate will put pressure on the bladder, leading to increased urinary frequency.

In males, what is the rectovesicular pouch?

The organs and structures located in the male pelvis are covered with a layer of peritoneum. The rectovesicular pouch sits between the bladder and the rectum and is the most inferior part of the abdomino-rectal cavity. This is where any fluid, abcess, etc. within the abdominal cavity will end up.

What is the urogenital hiatus? What are its borders? What passes through it?

The urogenital hiatus is a structure (opening) formed as a gap between the medial borders of the levator ani (particularly the puborectalis). The urogenital hiatus is the location at which the urethra and (in females) vagina passes through the levator ani.

The tendonous arch of the pelvis is the point where the obturator internus muscle meets which muscle group?

The pelvic diaphragm. He has really stressed the attached image/slide. It has appeared more than once during the last few lectures.

What three openings are present at the seminal colliculus? Describe the location of the seminal colliculus.

The seminal colliculus is a specific portion of the urethral crest. Specifically, the seminal colliculus is located in the region where the urethra passes through the prostate. There are openings at the seminal colliculus: the ejaculatory ducts and the orifice of prostatic utricle. Orifice of the prostatic utricle - In males, it is a vestigial structure that would have become the vagina. In males, it's a blind hole. Ejaculatory ducts - There are two openings where sperm enters the urethra. They are lateral to the prostatic utricle.

What area of the bladder contains a large number of stretch receptors?

The trigone area of the bladder. This portion of the bladder contributes significantly to our bodies ability to sense a fully bladder.

What is the trigone of the bladder? What is its significance?

The trigone is a smooth, roughly triangular portion on the inferior surface of the bladder. The trigone connects the two ureteric orifaces to the urethral oriface. The trigone has a mesoendodermal origin, whereas the rest of the bladder has a endodermal origin.

What is the urethral crest? Where is it found?

There is a thickening in the urethra as it runs through the prostate gland. This is the urethral crest. There are openings on the seminal colliculus (within the urethral crest) that are very important: ejaculatory ducts.