Reproductiver system

Penis Anatomy

• Main Structures:

• Corpora cavernosa (2): Paired erectile bodies on the dorsal side (when erect).

• Corpus spongiosum (1): Single erectile body on the ventral side (contains the urethra), expands distally to form the glans penis.

• Parts:

• Root (attached part):

• Crura: Proximal parts of corpora cavernosa, attached to pubic arch.

• Bulb of penis: Proximal corpus spongiosum, anchored to perineal membrane.

• Body (free part): Tethered continuation of crura and bulb, covered by skin.

• Ligaments:

• Suspensory ligament: From pubic symphysis to penis.

• Fundiform ligament: From linea alba, splits around penis and joins below.

• Orientation:

• Anatomical position is erect: corpora cavernosa = dorsal, corpus spongiosum = ventral.

Erection Mechanism

• Nerve Supply: Parasympathetic fibers from pelvic splanchnic nerves (S2–S4).

• Mechanism: Nerves cause arterial dilation → erectile tissue fills with blood → erection.

• Arterial Supply: Branches of internal pudendal artery.

• Sensory Innervation: Branches of pudendal nerve (S2–S4).

Female Homologue Structures

• Greater vestibular glands (Bartholin’s glands):

• Located posterior to bulbs of vestibule.

• Secrete mucus during sexual arousal.

• Female equivalent of bulbourethral glands (which are in the deep perineal pouch in men).

Muscles of the Superficial Perineal Pouch

1. Ischiocavernosus:

• Covers crura of penis/clitoris.

• Compresses crura to maintain erection.

2. Bulbospongiosus:

• Covers bulb of penis in men / bulb of vestibule in women.

• Aids in ejaculation and erection.

3. Superficial transverse perineal:

• Supports perineal body (not directly involved with erectile tissues).

Scrotum and Penis Surface Anatomy

• Scrotum:

• Male equivalent of labia majora.

• Formed from labioscrotal swelling fusion.

• Midline raphe indicates line of fusion (extends from anus to ventral penis).

• Penis Surface Features:

• External urethral orifice: At tip of glans.

• Raphe of penis: Midline line on ventral side.

• Frenulum: Connects glans to shaft skin.

• Corona: Raised edge of glans.

• Prepuce (foreskin): Skin fold covering glans, removed during circumcision.

Fascia in the Urogenital Triangle

• Colles’ fascia (membranous layer):

• Deep layer of superficial fascia.

• Attachments:

• Posteriorly: to perineal membrane (blocks spread into anal triangle).

• Laterally: to ischiopubic rami (prevents spread into thigh).

• Continuity:

• With abdominal fascia over pubic symphysis.

• Allows fluid to track to lower abdomen, but not into thigh or anal triangle.

Female Genital System

1. External Genital Organs (Vulva)

The vulva refers to the external genital structures located in the urogenital triangle of the perineum.

• Mons pubis: A rounded, fatty prominence anterior to the pubic symphysis.

• Labia majora: Prominent longitudinal folds of skin, enclosing and protecting the other external genital structures.

• Labia minora: Thin, hairless folds situated medial to the labia majora.

• Clitoris: An erectile organ composed of two crura, two corpora cavernosa, and a glans clitoris.

• Vestibule of the vagina: The cleft between the labia minora, containing the external urethral orifice and vaginal orifice.

• Greater vestibular glands (Bartholin’s glands): Mucous glands located posterolateral to the vaginal opening, homologous to the bulbourethral glands in males.

2. Internal Genital Organs

Located within the pelvic cavity, these include:

• Vagina: A fibromuscular canal extending from the vestibule to the cervix of the uterus.

• Uterus: A hollow, muscular organ consisting of a fundus, body, isthmus, and cervix.

• Uterine (fallopian) tubes: Muscular tubes that extend from the uterine horns to the ovaries and serve as the site of fertilization.

• Ovaries: Paired gonadal structures responsible for the production of ova and secretion of female sex hormones.

3. Blood Supply and Innervation

• Arterial supply:

• Internal organs: Uterine artery, ovarian artery, vaginal artery.

• External organs: Internal and external pudendal arteries.

• Innervation:

• Internal genitalia: Parasympathetic fibers from pelvic splanchnic nerves (S2–S4), sympathetic fibers from the inferior hypogastric plexus.

• External genitalia: Pudendal nerve, ilioinguinal nerve, and genital branch of the genitofemoral nerve.

4. Supporting Structures

• Broad ligament of the uterus: A double fold of peritoneum that supports the uterus, uterine tubes, and ovaries.

• Suspensory ligament of the ovary: Contains the ovarian vessels and connects the ovary to the lateral pelvic wall.

• Pelvic floor muscles: Including the levator ani and coccygeus, these muscles support the pelvic organs and contribute to continence.