Lecture 24: Male Reproductive Tract Flashcards Preview

CHI 280: Human Anatomy I > Lecture 24: Male Reproductive Tract > Flashcards

Flashcards in Lecture 24: Male Reproductive Tract Deck (21):

Tell me about the embryonic development
Slide 3

-the proximal mesonephric duct becomes the epididymis
-remainder of mesonephric duct becomes the ductus (vas) deferens and ejaculatory duct.

• Fetal testes produce Mullerian-inhibiting factor (MIF) which suppresses development of Mullerian (future female) ducts.
• 8th week: Leydig cells secreting testosterone.
• Testosterone induces masculine differentiation of mesonephric ducts and external genitalia.


Tell me about the testicular decent

• 7 months: testosterone stimulates descent of testes from pelvis to scrotum.
• Descent guided by gubernaculum extending from testis to floor of scrotal sac.
• Drags supplying blood vessels and nerves along behind => spermatic cord


What is the blood supply and the venous drainage of the penis?

• Blood supply: internal pudendal arteries, external pudendal arteries, dorsal arteries, deep arteries, arteries of the bulb
• Venous drainage: deep and
superficial dorsal veins.
Check out image on slide 14


Describe to me the scrotum "pouch".
Tell me the layers of the scrotum and covering of testis

Layers of scrotum and coverings of testis:
• Skin
• Dartos fascia and dartos
• External spermatic fascia
• Cremaster muscle
• Cremasteric fascia
• Internal spermatic fascia
• Tunica vaginalis (parietal)
• Tunica vaginalis (visceral)
• Tunica albuginea (innermost layer covering testis)
Slide 16


Tell me about the layers surrounding the testis

• Suspended in scrotum by spermatic cord.
• Tunica vaginalis: visceral & parietal layers of peritoneum.
• Tunica albuginea: “white coat” tough fibrous outer surface of testis.
Slide 17 and 18
Tunica albuginea forms septa inside testis.
Mature spermatozoa move from seminiferous tubules through rete testis and efferent ductules to be stored in the epididymis awaiting ejaculation. (Slide 20)


What is the blood supply of the testes?

Arterial supply:
• Testicular arteries
• Artery of ductus deferens

• Venous drainage:
• Pampiniform plexus ➡Right
testicular vein ➡ IVC
• Pampiniform plexus ➡Left testicular vein ➡ Left renal vein.


What lies in the spermatic cord?
What are the 3 coverings of the spermatic cord?

Ductus deferens
• Testicular artery
• Artery of ductus deferens
• Cremasteric artery
• Pampiniform plexus
• Sympathetic nerve fibres
• Genitofemoral nerve
• Lymphatic vessels

Three coverings:
• Internal spermatic fascia (derived from
transversalis fascia).
• Cremasteric fascia (derived from fascia of internal obliques and contains loops of cremaster muscle).
• External spermatic fascia (derived from external oblique aponeurosis and fascia)
• Cremaster muscle innervated by genitofemoral nerves (L1-L2).

The spermatic cord
-Begins at deep inguinal ring lateral to inferior epigastric vessels.
• Exits at superficial inguinal ring.
• Ends in scrotum at posterior pole of testis.



Posterior surface of testis.
• Head.
• Body.
• Tail.
• Efferent ductules of testis transport newly developed sperm from rete testis to epididymis.
Slide 30


Tell me about the ductus (vas) deferens "carrying away"

• Continuation of duct from tail of epididymis.
• Thick muscular walls, minute lumen.
• Primary component of spermatic cord.
• Crosses over external iliac vessels and enters pelvis.
• Ends by joining duct of seminal vesicles to form ejaculatory duct.


The seminal vesicle slide 33

Posterior to bladder.
• Anterior to rectum.
• Superior to prostate.
• Inferior to rectovesical pouch.
• Secrete thick alkaline fluid with fructose and coagulating agent that mixes with sperm as they enter the ejaculatory duct and urethra.


Ejaculatory ducts

Formed by union of ducts of seminal vesicles with ductus deferens.
• 2.5cm long.
• Arise near neck of bladder.
• Pass anteroinferiorly through posterior prostate.
• Opens into prostatic utricle.
• Prostatic secretions join seminal fluid in prostatic urethra AFTER ejaculatory ducts have terminated.


Tell me about the prostate gland?

Largest accessory gland of male reproductive tract.
• Surrounds prostatic urethra.
• Secretion = 1/3 of semen volume; milky, slightly acidic contains citrate and enzymes that activates sperm.
• Enters prostatic urethra via ducts when prostatic smooth muscle contracts during ejaculation.
Slide 35


Tell me about a prostate examination?

Benign hypertrophy of the prostate (BHP) is common after middle age.
• Enlarged prostate projects into urinary bladder and distorts prostatic urethra impeding urination.
• TURP = Transurethral resection of prostate.
Slide 36


Describe to me the bulbourethral gland and its function

Also called Cowper’s Gland.
• Pea-sized glands.
• Posterolateral to the intermediate part of urethra.
• Embedded in external urethral sphincter.
• Open through tiny holes into proximal part of the spongy urethra in bulb of penis.
• Under parasympathetic stimulation: Secrete clear mucous-like fluid during sexual arousal which neutralises traces of acidic urine in the
urethra and lubricates glans penis.


What are the 4 parts of the male urethra?

1. ntramural (pre-prostatic) part [0.5-1.5 cm]
2. Prostatic part [3-4 cm]
3. Intermediate (membranous) part [1-1.5 cm]
4. Spongy urethra [15cm]
Slide 38


Innervation of the interval genital organs of the male pelvis

Ductus deferens, seminal vesicles, ejaculatory ducts and prostate richly innervated by sympathetic fibres.
• Pre-synaptic sympathetic fibres originating from T12-L3 ➡ sympathetic trunk ➡ lumbar splanchnic nerves/hypogastric and pelvic plexuses.
• Pre-synaptic parasympathetic fibres originate from S2-S3 ➡ pelvic splanchnic nerves ➡ inferior hypogastric/pelvic plexuses.
• Synapses with post-synaptic sympathetic/parasympathetic neurons occur within plexuses
Slide 39


Take a look at the picture of the pudendal nerve on slide 41



Tell me the stages of an erection, ie how it comes about?

Parasympathetic stimulation

• Nitric oxide release

• Relaxation (dilation) of vascular smooth muscle

• Engorgement of erectile bodies with blood (compresses drainage veins -> retards blood outflow)


Ejaculation. What happens?

Ducts and glands contract to empty secretions.
• Closure of internal urethral sphincter (sympathetic via lumbar splanchnic nerves)
• Contraction of bulbospongiosus muscles from pudendal nerves.
• Sympathetic stimulation of rapid peristaltic-like contractions of ductus deferens.


Scrotum "pouch"
Layers of scrotum and coverings of testis:

-dartos fascia and dartos muscle
-external spermatic fascia
-cremaster muscle
-cremaster fascia
-internal spermatic fascia
-tunica vaginalis (parietal)
Tunica vaginalis (visceral)
-tunica albuginae (innermost layer covering testi)
Label all then on slide 16


Tell me a bit about the testis
Label the slides of them slide 18 and 19

Suspended in scrotum by spermatic cord
-tunica vaginalis: visceral and parietal layers if peritoneum
Tunica albuginae: white coast tough fibrous outer surface of testis