Male Reproductive System Flashcards
[3-minute video]: applied anatomy - Surgical emergency: Testicular Tortion
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Click on Answer for images and diagrams on the cross-sectional anatomy of the penis.
What are the parts of the penis?
- Root/radix
- Body/corpus
The root of the penis comprises three masses of erectile tissue: two crura and the bulb of the penis. Each crus is covered by the ____(a)____ muscle, and the bulb is covered by the ____(b)____ muscle. State the function of each of the stated muscles (c).
(a) ischiocavernosus
(b) bulbospongiosus
(c) Functions:
Ischiocavernosus: it helps stabilize the erect penis by compressing the crus penis and retarding the return of blood through the veins, thus maintaining penile erection.
Bulbospongiosus: it facilitates urination, ejaculation, and erection by compressing the bulb of the penis and corpus spongiosum. It also supports the perineal body.
The glans penis is an enlarged, conical structure at the distal end of the penis, with a sagittal slit-like aperture on its summit called the ____(a)____. The projecting margin of the base of the glans is called ____(b)____ which overhangs the neck of the penis.
(a) external urethral meatus
(b) corona glandis
Discuss the corpora cavernosa and the corpus spongiosum.
The corpora cavernosa are two cylindrical structures that run along the length of the penis and are filled with spongy erectile tissue. During sexual arousal, they become engorged with blood, leading to an erection.
The corpora spongiosum is a single cylindrical structure that runs along the underside of the penis and contains the urethra, allowing for the passage of urine and semen. It tapers slightly towards the distal end where it suddenly expands to form a conical enlargement - the glans penis. It also becomes engorged during arousal but to a lesser extent, preventing the urethra from pinching closed during an erection.
Both structures are essential for normal erectile function and are surrounded by a tough fibrous layer of connective tissue called the tunica albuginea, which helps to trap the blood within the corpora cavernosa, maintaining an erection.
Compare the layers of the anterior abdominal wall with the layers of the scrotum.
☯︎ The superficial fascia of the anterior abdominal wall is continuous with Dartos muscle.
☯︎ The external oblique muscle continues as the external spermatic fascia.
☯︎ The internal oblique muscle continues as the cremasteric muscle and fascia.
☯︎ The transversus abdominis muscle has no corresponding layer.
☯︎ Fascia transversalis continues as the internal spermatic fascia.
[Diagram]: layers of the scrotum
List four arteries that supply the scrotum.
(1) superficial external pudendal artery
(2) deep external pudendal artery
(3) scrotal branches of the internal pudendal artery
(4) cremasteric artery, a branch of the inferior epigastric artery
State the nerve supply to the scrotum. [also state the innervation of the dartos muscle]
anterior 1/3: ilioinguinal nerve, and genital branch of genitofemoral nerve
posterior 2/3: posterior scrotal branches of the perineal nerve and perineal branch of the posterior femoral cutaneous nerve of the thigh
Dartos muscle: sympathetic fibres through genital branch of the genitofemoral nerve
State the function of Dartos muscle.
The Dartos muscle is a layer of smooth muscle in the scrotum that functions to regulate the temperature of the testes. It does this by contracting to wrinkle the scrotal skin, which decreases surface area and reduces heat loss when it’s cold, and relaxing to increase surface area and enhance heat loss when it is warm, thus promoting optimal conditions for spermatogenesis.
Name the parts of the urethra starting from the posteriormost.
☛ prostatic urethra
☛ membranous urethra
☛ bulbar urethra
☛ penile urethra
[Diagram]
