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 Powered by TCPDF (www.tcpdf.org) 3 / 3.