Reproductive System > Anatomy > Anatomy

Home , Seminal vesicles, Spongy urethra, Tunica albuginea (penis), Urethra

Penis Reproductive System > Anatomy > Anatomy

Key Function: Conduct urine and semen to the outside environment. Key Anatomical Features:

Skin

• Prepuce covers glans, is retractable in the adult.

Vessels

• Superficial dorsal vein and artery

• Deep dorsal vein

• Deep arteries within corpus cavernosa

Connective tissues

• Deep fascia surrounds erectile bodies and binds them together

• Intercavernous fascia separate corpora cavernosa from corpus spongiosum.

Erectile bodies

• Covered in tunica albuginea

• Comprise vascular tissues that engorge with blood upon arousal.

Singular corpus spongiosum surrounds the urethra:

• Glans is distal expansion; corona is rim of glans

• Bulb is the widened proximal end

• The bulb anchors the corpus spongiosum to the perineal membrane (not shown);

• The bulb is wrapped in the bulbospongiosum muscle, which contracts to: force blood into the erectile tissues, eject residual urine from the urethra, and produce pulsatile movements during ejaculation. Paired corpus cavernosa (singular = cavernosum)

• Lie dorsal to corpus spongiosum

1 / 3 • Crus (singular = crura) of the corpus cavernosa extend laterally

• Crus attach to the pubic arch of the pelvis (not visible here), and are wrapped by ischiocavernosus muscles; like the bulbospongiosum, these muscles force blood into the erectile tissues.

Root

• Comprises bulb and crus of penis

Shaft

• Free, pendulous portion of penis between root and glans

Urethra

• Conducts semen to external environment

• Terminates at external urethral orifice

• Urethral glands secrete mucus to protect urethra from urine

Anatomical orientation

• Dorsal surface faces the torso

• Ventral surface faces away from the torso.

Semen/Seminal Fluid:

Semen (aka, seminal fluid)

• Comprises sperm and seminal plasma.

Sperm

• Gametes (aka, sex cells), produced by the testes

Seminal plasma

• Nourishes and protects the sperm

• Produced and secreted by the seminal vesicles, bulbourethral glands, and urethral glands.

Origins of semen:

2 / 3 Bulbourethral glands (aka, Cowper's glands)

• Secrete lubricating mucus prior to arrival of the rest of the semen into spongy urethra

Ampulla of ductus deferens

• Drains sperm

Seminal vesicles

• Drain viscous, sugary seminal plasma fluid

Ejaculatory duct

• Where sperm and seminal vesicle secretions mix; merger of ductus deferens and seminal vesicle

Prostate gland

• Secretes alkaline, enzyme-rich fluid that protects sperm

Ejaculate

• Semen after it has been ejected from the urethra.

Clinical correlation

• Male circumcision is the surgical removal of the some or all of the prepuce, which leaves the glans exposed.

• A "fractured" penis occurs when the tunica albuginea tears, typically as a consequence of abrupt angling of an erect penis; swelling and bruising result.

Embryology External Genitalia