Anatomy of the Male Pelvis and Perineum

Question 1

Give 4 pointers about the male pelvis

Answer 1

• Classic male shape pelvis is heart shaped
• As you pass through the outlet the male is narrowed to the lateral sides
• Narrow pelvic outlet
• The two pubic rami form a very acute angle

Question 2

Give 4 pointers about the female pelvis

Answer 2

• Classic female shape pelvis is oval shaped
• As you pass through the outlet the female is not narrowed
• Wide broad pelvic outlet
• The two pubic rami form a much more obtuse and broad angle

Question 3

What is the sub pubic angle in males and females?

Answer 3

50-60 vs 80-85

Question 4

Define Gynaecoid

Answer 4

• Gynaecoid – type allocated to normal female form. It has a round, transverse oval shape pelvic brim. It has a wide sub-pubic arch and sacrum is inclined posteriorly

Question 5

How is the male pelvis positioned?

Answer 5

• In males the sacrum can be tilted forward further forward, but in females the sacrum can’t tilt forward that much as you will disturb the pelvic outlet shape

Question 6

What is the scrotum?

What is its surface area changed by?

Why does one teste lie lower than the other?

Answer 6

• Suspended sack of skin and smooth muscle
• Surface area can be changed by contraction of dartos and cremaster muscle to help control temp.
• One testis lies at a lower level in the scrotum than the other to avoid compression

Question 7

What is the function of the testes?

Answer 7

• Spermatogenesis – at temp. approx. 3° lower then abdo. Cavity
• Production of spermatozoa takes place in the 400-600 seminiferous tubules

Question 8

What is the function of the Bulbourethral glands?

Answer 8

Lubricate the spongy urethra

Question 9

What is the function of the prostate and seminal vesicles?

Answer 9

Secretions from the prostate, together with secretions from the seminal vesicles contribute to the formation of semen
Lies at the neck of the bladder

Secretions contribute to the volume of ejaculatory semen

Question 10

Label the seminal vesicles, scrotum, prostate gland, testes, bulbourethral glands

Answer 10

On image

Question 11

Describe the decent of the testes

If the process is stopped what is it called?

Answer 11

• Development of the testes begins on the posterior abdominal wall
• Throughout embryological development the testes descend down the posterior abdominal wall and pushes through the layers of the wall to reach the scrotum
• To do this is passes through a pathway called the inguinal canal
• Structures therefore transmit from the scrotum back into the abdominal cavity
1. The testes start on the posterior abdominal wall
2. They develop between the perinatal peritoneum and transversalis fascia
3. They descend and are pulled down inferiorly by the gubernaculum (Cord like structure made of mesenchymal tissue)
4. The testes transverse through the anterior abdominal wall by passing through the inguinal canal at 20 weeks and by 32 weeks are in scrotum
5. If the process is stopped at any point it is called cryptorchidism (undescended testes) which can become maglignant/ high risk of subfertility

Question 12

What does the scrotum contain?

What are the layers of the scrotum?

What are the layers of the scrotum and what do they form from?

Answer 12

• The scrotal sac contains the testes, the epididymis and lower end of spermatic cord
• The remnant of the process vaginalis
• To help descend the testes the gubernaculum will pass from the developing testes down through the inguinal canal into the scrotum, the testes follow this pathway
• Underneath the skin is a superficial fascia, campus fascia and scarpus fascia and contribute to the scrotum
• Campus fascia enters, loses its fatty layer and replaced by a muscle layer called the dartos muscle which enter the wall of the scrotum
• Scarpa fascia is deep to campus fasica and will contribute towards the testes, it then enters the wall of the scrotum
• So you have the skin, superficial fascia’s, then the 3 layers of abdominal wall
• The scrotum develops with these three layers
• The internal spermatic fascia comes from the transversalis fascia, the cremasteric muscle coming from the internal oblique muscle and the external spermatic fascia from the external oblique muscle (aponeurosis)

Question 13

What structures descend into the scrotum?

Answer 13

• The superficial opening of the inguinal canal is called the superficial ring, the spermatic cord contains the vas deferens and testicular arteries will descend into the scrotum

Question 14

What layers do the testes aquire?

Answer 14

o Peritoneal diverticulum called processus vaginalis from L1 through abdominal wall acquiring a tubular sheath from each layer
o Through external oblique aponeurosis - creates superficial inguinal ring = external spermatic fascia around spermatic cord and testes
o Passes through internal oblique = cremaster muscle (fascia) (surrounds scrotum and retracts the testes)
o Under transversus abdominis = no covering from this layer, does not form part of the spermatic cord or testes.
o Passes through deep inguinal ring (transversalis fascia) = internal spermatic fascia

Question 15

What are the 5 structures found within the spermatic cord?

Answer 15

1. Vas deferens = cordlike muscular duct which transports spermatozoa from the epididymis to the urethra
2. Testicular artery = L2 branch of the aorta supplies the testes and epididymis
3. Testicular veins = pampiniform plexus from the border of the testis forms a single vein at the level of the deep inguinal ring
4. Lymph vessels = to para-aortic nodes at root of testicular artery
5. Autonomic nerves = sympathetic on artery from renal or aortic plexuses

Question 16

What other 4 structures are found in the spermatic cord?

Answer 16

6. Cremasteric artery (from inf epigastric) to cremaster fascia
7. Artery of the vas deferens (from inf vesical)
8. Genital branch of the genitofemoral nerve which supplies the cremaster muscle
9. Remnant of processus vaginalis, Tunica vaginalis

Question 17

Label the spermatic cord structures

Answer 17

On image

Question 18

What is the function of the testes?

What tubules are found within the testes?

Answer 18

• Creates sperm
• Composed of seminiferous tubules which produce sperm (400-600)
• Modified at each end – ‘straight tubules’ which are connected to rete testis – collecting chamber called rete testis
• From the rete testis there are 12-20 efferent ductules originate from upper end of rete testis, penetrate capsule and connect with epididymis

Question 19

What is the function of the epididymis?

Answer 19

• Single, long, coiled duct on posterior surface of testes
• Efferent ductules form an enlarged mass on posterior superior pole of testis – head
• Drain into body
• Body enlarges at the tail, which is continuous with the ductus deferens
• The tail then forms the vas deferens within spermatic cord.
• Sperm then follows the pathway to enter into the prostatic urethra

Question 20

Where does the Ductus (Vas) Deferens travel?

Answer 20

The anatomical course of the vas deferens:

1. It is continuous with the tail of the epididymis.
2. Travels through the inguinal canal, as part of the spermatic cord.
3. Moves down the lateral pelvic wall close to the ischial spine.
4. Turns medially to pass between the bladder and the ureter and then travels downward on the posterior surface of the bladder.
5. The inferior narrow part of the ampulla joins the duct from the seminal vesicle to form the ejaculatory duct.
6. Vas deferens passes over ureters

Question 21

Label the ductus deferens

Answer 21

On image

Question 22

What forms the ejaculatory ducts?

Answer 22

• We can see the vas deferens passes and joins with the duct of the seminal vesicles to form the ejaculatory ducts
• They then enter the posterior aspect of the prostate and open into the prostatic urethra

Question 23

Where do the seminal vesicles lie in relation to the bladder?

What is there function?

Describe there size

Answer 23

• The seminal vesicles are paired tubular glands posto-inferior to the urinary bladder
• Provide a huge proportion of the total volume of semen, about 70% of the total volume of semen
• Each seminal vesicle spans approx. 5cm, though uncoiled is approx. 10-15cm in length

Question 24

Where does the prostate gland lie and function?

Answer 24

• Sits at the base of the bladder and on the pelvic diaphragm
• Fibromuscular glandular organ - produces secretions that themselves constitute about 30% of the volume of an ejaculate

Question 25

What supports the prostate?

Answer 25

• Supported by the puboprostatic ligament anteriorly and by the levator prostatae of the pelvic diaphragm inferiorly

Question 26

Where does the ejaculatory ducts open up in relation to the urethra?

What is the summit of the urethral crests called?

Answer 26

• Ejaculatory ducts open on either side of the urethral crests. The urethral crest reaches a summit called the seminal colliculus, with a pit at the apex called the prostatic utricle (remnant of paramesonephric duct

Question 27

What are the 3 zones of the prostate?

Answer 27

• The central zone (red) – which forms the base of the gland which that surrounds the ejaculatory ducts
• Transitional zone (green) – small glandular zone that surrounds a portion of the urethra between the urinary bladder and seminal colliculus
• Peripheral zone (blue) – largest zone making up 70% of gland and surrounds most of the central zone and partially surrounds the distal part of the prostatic urethra

Question 28

What are the lobes of the prostate?

Answer 28

• The median lobe of the prostate is small
• Posterior lobe
• Lateral lobes
• Anterior lobes

Question 29

Label the prostate

Answer 29

On image

Question 30

What is the prostate gland supported by anteriorly and inferiorly?

Label these

Answer 30

• Anteriorly: supported by the puboprostatic ligament

* Inferiorly: supported by levator prostatae of the pelvic diaphragm

Question 31

What is a prostatic enlargement?

What does it cause?

How is it assessed?

Answer 31

• The sphincter vesicae passes around the neck of the bladder area
• The median lobe enlarges as males get older, which can occlude the urethra causing urinary symptoms from this process called begin prostatic hyperplasia
• The median lobe passes through the neck of the bladder area keeping open the sphincter vesicae so urine is released from the neck of the bladder

 May affect all, or part of the prostate
 May be benign or malignant
 Commonly seen in the DR (males aged 50+)
 Assessed with ultrasound by a trans-rectal approach and by trans-rectal biopsy of the prostate gland

Question 32

What are the causes, symptoms, diagnosis and complications of testicular torsion?

Answer 32

• Causes
o inadequate fixture of testis to scrotum – inadequate attachment of the testes via the scrotal ligament (previously the gubernaculum)
o excessively large tunica vaginalis –
o activity that causes rotation of the testes
• Symptoms
o severe pain in the scrotum, extending up through the inguinal region
o Testis higher up than normal position
o Can produce fever
o Absence of cremasteric reflex
• Diagnosis
o Presenting signs and symptoms
o Ultrasound if diagnosis is unclear (Doppler ultrasound scan)
• Complications: If not treated quickly, testicular artery may become occluded, leading to ischaemia and eventually necrosis of the testis

Question 33

What is a Varicocele?

Answer 33

Develop as a result of dilatation and tortuosity of veins of the pampiniform plexus

Enlarge of the pampiniform plexus (venous system of testes)

In a varicocele the valves do not function correctly within the veins causing blood to pool and enlarge the vein

Question 34

What are the symptoms, diagnosis and treatment for a Varicocele?

Answer 34

• Symptoms
o ‘Bag of worms’ appearance.
o May experience pain that gets worse when standing or during physical activity, become more intense as the day goes on.
o May have problems with fertility.
• Diagnosis:
o Presenting signs and symptoms.
o Ultrasound if diagnosis is unclear (Doppler ultrasound scan) or via a venogram.
• Treatment:
o Catheter-directed embolization: Blocks blood flow using a coil or sclerosants. Complications: may not go away or comes back/the coil moves.
o Varicocelectomy: Veins tied off with sutures. Complications: may not go away or comes back, build up of fluid in the testicles (hydrocele), injury to the testicular artery.

Question 35

What is the penis made of?

Answer 35

The penis is composed mainly of two corpora cavernosa and the single corpus spongiosum

Question 36

What forms the root and the body of the penis?

What does the urethra pass through?

What are the 3 arterial supplies to the penis?

Answer 36

• The root (purple) (attached to perineal membrane) consists of two crura, which are the proximal parts of the corpora cavernosa attached to the pubic arch
• The bulb of the penis is the proximal part of the corpus spongiosum, anchored to the perineal membrane
• The body is formed by tethering of the two proximal free parts of the corpora cavernosa and the related free part of the corpus spongiosum
• The urethra passes through the corpus spongiosum and the corpus spongiosum is expanded distally to form the glans penis. The urethra orifice opens to the distal aspect of the glans penis
• The spongiosum become dilated with blood causing it to become erect. There are 3 pairs of arteries supplying the penis:
o Two deep arteries running through the corpora cavernosa and two corpus spongiosum. These arise from the pudendal artery

Question 37

Label the external male genitalia

Answer 37

On image

Question 38

What does the:

• Ischiocavernosus muscles
• Bulbospongiosus muscle:

do?

Answer 38

• Ischiocavernosus muscles:
o Surround the erectile tissue of crura which are the proximal parts of the corpora cavernosa
• Bulbospongiosus muscle:
o Surrounds the erectile tissue of the bulb of the penis which is the proximal part of the corpus spongiosum

Question 39

Label and name the fundiform ligament

Answer 39

• As the root of the penis passes anteriorly and joins together to form the body it is supported by the thickening of fascia coming from the anterior abdominal wall tethers the body of the penis to the body called the fundiform ligament (tethers body of the penis up towards the abdominal wall)