Module 18: Male Reproductive System and Pelvic Floor

Function of the male reproductive system

Produces sperm, androgens, facilitates copulation.

Primary sex organ

Testes, produce sperm/testosterone.

Accessory sex organs

Ducts, glands, penis, transport/enhance semen.

Scrotum

Skin-covered sack housing testes, 2-4°C below core.

Raphe

Raised medial thickening on scrotum surface.

Dartos muscle

Subcutaneous scrotum layer, elevates testes in cold.

Cremaster muscle

Covers testes, elevates in cold, from internal oblique.

Spermatic cord

Contains ductus deferens, testicular artery, pampiniform plexus, nerves.

Inguinal canal

Passage for spermatic cord through abdominal wall.

Internal spermatic fascia

Inner layer of spermatic cord.

External spermatic fascia

Outer layer of spermatic cord.

Testicular artery

Supplies testes, from aorta.

Pampiniform plexus

Venous network cooling testicular blood.

Autonomic nerves in spermatic cord

Regulate testicular function, vas deferens contraction.

Ductus deferens

Muscular tube transporting sperm to ejaculatory duct.

Testes

Male gonads, produce sperm/testosterone, ~4-5 cm.

Tunica vaginalis

Serous membrane covering testes, parietal/visceral layers.

Parietal layer

Outer layer of tunica vaginalis.

Visceral layer

Inner layer of tunica vaginalis, contacts tunica albuginea.

Tunica albuginea

Dense connective tissue covering testes, forms septa.

Mediastinum testes

Central connective tissue supporting rete testes.

Septa

Divide testes into 300-400 lobules.

Seminiferous tubules

Sites of sperm production in lobules.

Rete testes

Tubule network collecting sperm from seminiferous tubules.

Efferent ductules

15-20 tubes from rete testes to epididymis.

Epididymis

~6 m coiled tube, matures/stores sperm.

Duct of the epididymis

Coiled tube for sperm maturation/movement.

Head of the epididymis

Receives sperm from efferent ductules.

Body of the epididymis

Middle section, continues sperm maturation.

Tail of the epididymis

Stores mature sperm until ejaculation.

Ampulla (ductus deferens)

Widened end joining seminal vesicle.

Ejaculatory duct

Short duct from ampulla/seminal vesicle to urethra.

Seminal vesicles

Paired glands, produce ~60% semen volume (fructose).

Prostate gland

Walnut-sized, secretes milky fluid for semen coagulation.

Bulbourethral glands

Paired, secrete pre-ejaculate for lubrication.

Semen

Sperm (5%) plus seminal vesicle/prostate/bulbourethral fluids.

Penis

Copulatory organ, flaccid for urination, erect for intercourse.

Root of the penis

Bulb and crura, anchors penis.

Bulb of the penis

Root portion, base of corpus spongiosum.

Crura

Root portions, bases of corpora cavernosa.

Body (shaft) of the penis

Main portion, contains erectile tissue.

Glans

Sensitive tip of penis, high nerve density.

External urethral orifice

Urethral opening at glans.

Corporas cavernosa

Two lateral erectile tissue chambers in penis.

Corpus spongiosum

Single erectile tissue surrounding penile urethra.

Prepuce

Foreskin, covers glans, removable by circumcision.

Perineum

Diamond-shaped region, pubic symphysis to coccyx.

Urogenital triangle

Anterior perineal region, contains genitals.

Anal triangle

Posterior perineal region, contains anus.

Pelvic diaphragm

Deepest pelvic floor layer, levator ani, coccygeus.

Urogenital diaphragm

Middle layer, deep transverse perineal, sphincters.

Superficial perineal layer

Outermost layer, ischiocavernosus, bulbospongiosus.

Levator ani

Pelvic diaphragm muscles: iliococcygeus, pubococcygeus, puborectalis.

Iliococcygeus

Levator ani muscle, supports pelvic organs.

Pubococcygeus

Levator ani muscle, supports pelvic floor, continence.

Puborectalis

Levator ani muscle, maintains fecal continence.

Coccygeus

Pelvic diaphragm muscle, supports coccyx.

Deep transverse perineal muscle

Urogenital diaphragm, stabilizes perineum.

External urethral sphincter

Urogenital diaphragm, voluntary urination control.

External anal sphincter

Urogenital diaphragm, voluntary defecation control.

Ischiocavernosus

Superficial perineal, aids erection/clitoral engorgement.

Superficial transverse perineal muscle

Superficial perineal, stabilizes perineum.

Bulbospongiosus

Superficial perineal, aids ejaculation/vaginal contraction.

Pudendal nerve

Innervates pelvic floor muscles, external sphincters (S2-S4).

Function of levator ani

Supports pelvic organs, maintains continence.

Function of coccygeus

Supports pelvic floor, aligns coccyx.

Function of external urethral sphincter

Voluntary control of urination.

Function of external anal sphincter

Voluntary control of defecation.

Function of ischiocavernosus

Aids erection (male), clitoral engorgement (female).

Function of bulbospongiosus

Aids ejaculation (male), vaginal contraction (female).

Vasectomy

Surgical sterilization cutting ductus deferens.

Benign prostatic hyperplasia (BPH)

Prostate enlargement, compresses urethra, urinary issues.

Prostate cancer

Common cancer in men, detected by biopsy, varies in aggression.

Innervates the pelvic floor

Pudendal nerve, controls voluntary sphincters.