Deep Perineal Pouch - Easy + Clinical + Diagrams

Source: Gray's Anatomy for Students

What Is It?

The deep perineal pouch (also called the deep perineal space) is a narrow compartment located immediately superior to the perineal membrane, within the urogenital triangle of the perineum. It is open above and not separated from superior pelvic structures by a distinct fascial layer - meaning it directly communicates with the pelvic floor above.

Position at a Glance

Pelvic floor showing deep perineal pouch relationship to perineal membrane and levator ani (Fig. 5.7)

Pelvic floor in a woman - the deep perineal pouch sits as a thin region just above the perineal membrane, below the levator ani.

Boundaries

Wall	Structure
Floor (inferior)	Perineal membrane (thick triangular fibrous sheet)
Roof (superior)	Open - merges with pelvic floor above
Lateral walls	Ischiopubic rami
Posterior border	Free - anchored to perineal body
Anterior gap	Small gap between perineal membrane and inferior pubic ligament

Perineal membrane and deep perineal pouch - inferior view (A) and superolateral view (B) showing the pouch as a thin layer above the membrane

Contents - "2 Muscles + 2 in Women + Vessels + Nerves"

Muscles (Table 5.3)

Muscle	Origin	Insertion	Nerve	Function
External urethral sphincter	Inferior ramus of pubis + walls of deep perineal pouch	Surrounds membranous urethra	Pudendal nerve (S2-S4)	Compresses membranous urethra; relaxes during micturition (voluntary control)
Deep transverse perineal	Medial ischial ramus	Perineal body	Pudendal nerve (S2-S4)	Stabilizes position of perineal body
Compressor urethrae (women only)	Ischiopubic ramus (each side)	Blends with partner anterior to urethra	Pudendal nerve (S2-S4)	Accessory sphincter of urethra
Sphincter urethrovaginalis (women only)	Perineal body	Passes forward lateral to vagina, blends anterior to urethra	Pudendal nerve (S2-S4)	Accessory sphincter (also may help close vagina)

Muscles in the Deep Perineal Pouch - (A) women showing EUS, sphincter urethrovaginalis, compressor urethrae, deep transverse perineal; (B) men showing EUS and deep transverse perineal

Neurovascular Contents

Dorsal nerve of penis/clitoris - enters and traverses the lateral margin of the deep perineal pouch, exits anteriorly to reach the dorsum of the penis/clitoris; sensation to glans
Terminal part of internal pudendal artery - enters pouch, gives off: artery to bulb of penis, urethral artery, deep artery of penis, and dorsal artery of penis (or equivalents in women)
Bulbo-urethral glands (Cowper's glands) (in men) - small paired glands in the deep perineal pouch; ducts pierce perineal membrane to drain into penile urethra

Structures Passing Through

Urethra - passes vertically through a hiatus in the perineal membrane going from pelvic cavity to perineum; surrounded here by the external urethral sphincter
Vagina (in women) - passes through a hiatus just posterior to the urethral opening

Medial View - Relationship to Penis and Pelvic Floor

Medial view showing deep perineal pouch above perineal membrane, below levator ani, with root of penis inferior

Key Functions (Easy Summary)

Voluntary urinary control - the external urethral sphincter here is the voluntary sphincter; when damaged (e.g., in pelvic fracture or prostatectomy), you get stress incontinence
Pelvic floor support - the deep perineal pouch + perineal membrane together support pelvic viscera from below, spanning the urogenital hiatus
Penile/clitoral innervation and blood supply - the dorsal nerve and internal pudendal artery pass through here to supply erectile tissues
Stabilization of perineal body - the deep transverse perineal muscles anchor the perineal body, which is the junction point for multiple pelvic floor muscles

Clinical Significance

Scenario	Mechanism
Urinary incontinence after prostatectomy	Damage to external urethral sphincter in deep perineal pouch; no voluntary urethral closure
Pelvic fracture urethral injury	The membranous urethra (passing through deep perineal pouch) is the most common site of rupture in pelvic fractures - because it is relatively fixed here
Perineal laceration/episiotomy repair	Deep transverse perineal muscle and perineal body are key structures to reconstruct to restore pelvic floor integrity
Pudendal nerve block	Anesthetic injected near ischial spine to block pudendal nerve before it branches; anesthetizes all structures of the deep perineal pouch
Bulbo-urethral gland cyst/abscess	Glands in deep perineal pouch can become infected; present as a perineal swelling between scrotum and anus
Female stress urinary incontinence	Weakness of compressor urethrae and sphincter urethrovaginalis (women-specific deep pouch muscles) contributes to urethral incompetence

Compare: Deep vs. Superficial Perineal Pouch

Feature	Superficial Perineal Pouch	Deep Perineal Pouch
Location	Below perineal membrane	Above perineal membrane
Contents	Crura/bulb of penis (erectile tissue), ischiocavernosus, bulbospongiosus, superficial transverse perineal	External urethral sphincter, deep transverse perineal, bulbo-urethral glands, dorsal nerve/artery of penis
Roof	Perineal membrane	Open (no superior fascia)
Floor	Membranous (Colles') fascia	Perineal membrane
Clinical injury	Straddle injury → blood/urine in superficial pouch	Pelvic fracture → membranous urethral rupture

Gray's Anatomy for Students, Table 5.3 and Figs. 5.36-5.37, pp. 531-533

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