Lecture 21 - Reproductive Systems: Assigned Male at Birth Flashcards
What are the 3 classifications for the major components of the AMAB reproductive system?
- Gonad-related
- Ducts
- Accessory glands
What are the gonad-related components?
- Scrotum
- Testes
- Epididymis
What are the ducts of the AMAB reproductive system?
- Ductus/Vas deferens
- Ejaculatory ducts
- Urethra
- Penis
What are the accessory glands of the AMAB reproductive system?
- Prostate gland (x1)
- Seminal vesicles (x2)
- Bulbourethral glands (x2)
What is the scrotum?
External component of the genital organ (w/ penis)
What structure of the AFAB is analogous to the scrotum?
Labia majora
What is the structure of the scrotum?
Dual-layered sack suspended from the perineum
What is found in the musculofascial layer?
Tunica dartos muscle
What is the tunica dartos muscle?
Subcutaneous muscle layer
What is the function of the tunica dartos muscle?
Regulate scrotal temperature
How can the tunica dartos muscle regulate scrotal temperature?
By reducing surface area to prevent heat loss (autonomic)
What is the process of sperm production called?
Spermatogenesis
What is the optimal temperature for spermatogenesis?
2-6° below core body temperature
What is the plexus found near the scrotum?
Pampiniform plexus
What is the pampiniform plexus?
A network of small spermatic veins in the spermatic cord
What does the pampiniform plexus drain into?
Testicular vein
What is a varicocele?
Engorgement of blood in the testicular vein due to a back up in the left renal vein
What is the function of the pampiniform plexus?
Regulate the temperature of the testes
How does the pampiniform plexus regulate the temperature of the testes?
By absorbing/dissipating heat from within the testicular artery
What does the spermatic cord do?
Communicates between abdominopelvic cavities and testis in the scrotum via the inguinal canal
Where does the spermatic cord pass?
Through the inguinal canal
What are the contents of the spermatic cord?
- Vas deferens
- Pampiniform plexus
- Testicular a. + v.
- Lymphatics
- Cremaster muscle and a. + v.
- Testicular innervation
What contributes to the layers of the inguinal canal?
Superficial to deep:
1. External oblique
2. Internal oblique
3. Transversus abdominis
4. Transversalis fascia
Where do the gonads develop?
Between the parietal peritoneum and abdominal wall fascia
What occurs to the testes during development?
Testes descend into the scrotum
Why do the testes become external?
To ensure the optimal temperature of the testes
What occurs during the descent of the testes?
- Layers of anterior abdominal wall evaginate
- Testes pulled with them
How does descent occur?
Via the shortening gubernaculum
What is the gubernaculum?
Fibrous tract that becomes the scrotal ligament
What do the AAW layers surround after descent?
They surround the testes spermatic cord
What do the AAW layers surrounding the testes become?
Layers of the spermatic fascia
What does the external oblique become around the testes?
External spermatic fascia
What does the internal oblique become around the testes?
Cremaster muscle
What does the transversalis fascia become around the testes?
Internal spermatic fascia
What does the peritoneum become around the testes?
Tunica vaginalis
What are the internal structures of the testis?
- Seminiferous tubules
- Straight tubules
- Rete testis
- Efferent ductules
- Epididymis
What occurs in the seminiferous tubules?
Site of spermatogenesis (production of spermatozoa)
What occurs in the rete testis?
Collecting chamber
What is the function of the straight tubules?
Connects seminiferous tubules to rete testis
What is the function of the rete testis?
Reabsorption of fluid to increase sperm concentration
Where do the efferent ductules run?
From the rete testis through the capsule to the epididymis
What is the epididymis?
Long coiled duct in the scrotum
What is the role of the epididymis?
Maturation of spermatozoa and storage (2-3 months)
What is characteristic of the head of the epididymis?
Efferent ductules form an enlarged coiled mass
What is characteristic of the body of the epididymis?
Run along the posterolateral aspect of the testis
What is characteristic of the tail of the epididymis?
- Found on the inferior pole of the testis
- Continuous with vas deferens
What is the tunica vaginalis?
Covered by a closed sac of the peritoneum
What is the tunica albuginea?
Thick testicular capsule
What is the vas deferens?
- Long tube conduit
- Made of smooth muscle
What is the function of the epididymis?
Transports spermatozoa from the tail of the epididymis in the scrotum to the ejaculatory duct in the pelvic cavity
How does the spermatozoa go from the epididymis to the ejaculatory duct?
Via the spermatic cord
Where does the vas deferens first travel?
Up the spermatic cord, through the inguinal canal
Where does the vas deferens go at the deep inguinal ring?
- Bends medially around lateral side of the inferior epigastric a.
- Crosses the external iliac v. at pelvic inlet
- Enters the pelvic cavity
Where does the vas deferens pass after entering the pelvic cavity?
Descends medially along the pelvic wall, deep to the peritoneum
What does the vas deferens cross over?
- Crosses over the ureter
- Inferior medially along the base of the bladder
What portion of the vas deferens enlarges?
The ampulla of the vas deferens
What does the vas deferens join?
The seminal vesicle
What does the joining of the vas deferens and seminal vesicle form?
The ejaculatory duct
What are the seminal vesicles?
- Paired accessory glands
- Coiled tubes situated between the bladder and rectum
What is the function of the seminal vesicles at ejaculation?
Secretes most of the fluid that becomes semen
Where are the seminal vesicles located?
Lateral to the ampulla of the vas deferens at the base of the bladder
What other function does the seminal vesicle have?
Provides nourishment to spermatozoa
What is the prostate?
- Unpaired accessory sex gland
- Surrounds the urethra
Where is the prostate located?
- Lies immediately inferior to the bladder
- Posterior to the pubic symphysis
- Anterior to the rectum
What is the shape of the prostate?
Inverted cone (base at the neck of the bladder, tip on pelvic floor)
What is the prostate composed of?
Individual glandular complexes
Where do these glandular complexes empty into?
The urethra through individual openings
What is the function of the prostate at ejaculation?
- Secretes a slightly alkaline fluid into semen
- Helps neutralize the acidity of the vaginal tract
- Promotes survival of spermatozoa
What are the bulbourethal glands?
Small, paired, pea-shaped mucous glands
Where are the bulbourethral glands located?
- Situated in the deep perineal pouch
- Posterior to the urethra
Where do the ducts of glands pass?
Through the perineal membrane
What do the bulbourethral glands drain into?
The urethra at the root of the penis
What is the function of the bulbourethral glands?
Pre-ejaculatory emission of fluid that neutralizes acidic urine that may be present in the urethra and lubricates it
What is the perineal membrane?
- A thick triangular fascial structure attached to inferior rami of the pubic bones
- Free posterior edge
What does the perineal membrane overlie?
The urogenital hiatus
What does the perineal membrane provide?
Attachment for external genitalia and opening for urethra
What is contained in the deep perineal pouch?
- Thin muscular sheet
- Sphincter muscle for urethra
- Bulbourethral glands
Where is the deep perineal pouch located?
Between the perineal membrane and pelvic diaphragm
What are the erectile tissues of the penis?
- Corpora cavernosa (x2)
- Corpus spongiosum (x1)
Where are these erectile tissues located?
Within the thick fascia, Buck’s
What are the 3 parts of the penis?
- Root
- Body
- Glans
What is the root of the penis?
Anchored to the perineal membrane and pubic arch
What are the parts of the penis?
- Crura (2x)
- Bulb (1x)
What is the crura of the root of the penis?
Proximal parts of the corpora cavernosa
What is the bulb of the root of the penis?
Proximal part of corpus spongiosum
What forms the body of the penis?
The “free” parts of corpora cavernosa and corpus spongiosum
What is the glans of the penis?
Expansion of the corpus spongiosum (over the distal end of the corpora cavernosa)
Where are the skeletal muscles of the penis located?
Only associated with the root
What are the skeletal muscles of the penis?
- Ischiocavernosus
- Bulbospongiosus
Where is the ischiocavernosus located?
- Covers crura of the penis
- Anchored to the ischial tuberosity and pubic arch
What is the function of the ischiocavernosus?
Moves blood from the crura into the body of the penis during erection
Where is the bulbospongiosus located?
- Covers the bulb of the penis
- Anchored to the perineal membrane and body
What is the function of the bulbospongiosus?
- Moves blood into distal penis (erection)
- Pulsatile emission of the semen (ejaculation)
- Emptying urethra during urination
What is the innervation of the skeletal muscles of the penis?
Pudendal nerve (S2-S4)
What type of innervation does the pudendal nerve give?
Somatic innervation
What is the arterial blood supply of the penis?
Three paired arteries from the internal pudendal arteries
What are the 3 paired arteries?
- Arteries of the bulb of the penis (to bulb)
- Dorsal penile a.
- Deep penila a.
Where does the dorsal penile a. run?
Along the dorsum of the penis
Where does the deep penile a. run?
Within corpora cavernosa
What is the venous drainage of the penis?
Occurs with 1 unpaired vein
What is the 1 unpaired vein for venous drainage?
Deep dorsal vein
Where does the deep dorsal vein pass?
Under the pubis symphysis
What does the deep dorsal vein join?
The prostatic plexus
What does the deep dorsal vein drain into?
External pudendal v.
What occurs during erection?
- Vasodilation of deep penile arteries
- Engorgement of corpora cavernosa
- Contraction of bulbo and ischiocavernosus
- Blood forced into distal region of penis
- Compression of deep dorsal vein under Buck’s
- Venous outflow inpeded
= Erection
What is the length of the urethra in an AMAB?
20 cm long
Where does the urethra run?
From the bladder to the external urethral orifice
How many bends are in the urethra?
Two bends (when the penis is flaccid)
Where does the urethra pass through?
- Prostate
- Deep perineal pouch
- Perineal membrane
- Penis
What are the parts of the urethra for an AMAB?
- Preprostatic urethra
- Prostatic part
- Membranous part
- Spongy (penile) urethra
How long is the preprostatic urethra?
1 cm long
What surrounds the preprostatic urethra?
The internal urethral sphincter (autonomic)
What is the function of the internal urethral sphincter during ejaculation?
Prevents retrograde movement of semen into the bladder
How long is the prostatic part?
3-4 cm long
What surrounds the prostatic part?
Prostate (where the ejaculatory duct and glandular complex empties)
How long is the membranous part?
~ 1 cm long
What surrounds the membranous part?
External urethral sphincter (somatic)
What does the membranous part of the urethra pass through?
Deep perineal pouch
How long is the spongy urethra?
~ 15 cm long
Where is the spongy urethra located?
- Within the corpus spongiosum
- Ends at the external urethral orifice
What takes place in the spongy urethra?
Bulbourethral glands empty into the bulb region
What is the peritoneum?
Continuation of the parietal peritoneum of the abdominal cavity through the pelvic inlet
What does the peritoneum drape over and form?
Drapes over: Pelvic viscera
Creating: Pouches and folds between viscera
In an AMAB, where does the peritoneum run?
- Drapes over bladder and superior pole of seminal vesicles
- Reflects onto anterior aspect of rectum
What does the peritoneum in an AMAB create?
Rectovesical pouch
What is the rectovesical pouch?
- Space between rectum and bladder
- Represents the lowest part of the peritoneal cavity
What causes an accumulation of fluid in the rectovesical pouch?
Inflammation or infection of the peritoneal cavity
