STEP 1 • ANATOMY EXPLORER

The floor & the room below

Tap the colored anatomy. Build the picture from pelvis → floor → perineum.

Levator ani Puborectalis Coccygeus

Big picture: Pelvic diaphragm = levator ani + coccygeus. Levator ani = puborectalis + pubococcygeus + iliococcygeus. Main roots: S3–S4 via nerve to levator ani.

Perineum

Diamond-shaped region below the pelvic diaphragm, not the pelvic floor itself.

Division line

A transverse line connecting the two ischial tuberosities.

FROM SUPERFICIAL TO DEEP

Skin and superficial fascia

The external covering of the urogenital triangle.

Superficial perineal pouch

Between superficial fascia and perineal membrane. Contains erectile roots plus ischiocavernosus, bulbospongiosus, and superficial transverse perineal muscles.

Perineal membrane

Strong fibrous sheet spanning the pubic arch; supports and anchors structures.

Deep perineal pouch

Superior to the membrane. Contains external urethral sphincter complex; bulbourethral glands in males.

Pelvic diaphragm

Muscular roof above the perineum: levator ani + coccygeus.

Ischioanal fossa

Fat-filled wedge lateral to the anal canal. Lets the canal expand during defecation.

Abscess may spread

Perineal body

Central fibromuscular anchor between urogenital and anal regions. Multiple muscles meet here.

Childbirth injury

Step 1 trap: The perineal membrane divides the superficial and deep pouches; the pelvic diaphragm lies above both.

ONE-MINUTE CHECK

Which muscle acts as a sling that preserves the anorectal angle?

Puborectalis is the U-shaped sling. It relaxes during defecation to straighten the anorectal angle.

Where is the external urethral sphincter complex found?

The deep pouch contains the external urethral sphincter complex. Erectile roots and superficial muscles are in the superficial pouch.

Memory hook: Floor supports. Puborectalis slings. Perineum divides. Membrane separates.

Pelvic Floor Map