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Internal pudendal artery

The internal pudendal artery is the principal arterial supply to the perineum, external genitalia, and anal canal. It arises from the anterior division of the internal iliac artery, exits the pelvis through the greater sciatic foramen, and re-enters through the lesser sciatic foramen to reach the pudendal (Alcock) canal.

Its deep course within the pelvis and perineum makes it crucial for genitourinary function, erectile physiology, and anorectal vascular support. It is a key surgical landmark in pelvic surgery, perineal reconstruction, and interventional procedures.

Synonyms

  • A. pudenda interna

  • Pudendal artery

Origin, Course, and Termination

Origin:

  • Arises from the anterior division of the internal iliac artery.

Course:

  • Leaves pelvis via greater sciatic foramen, inferior to piriformis

  • Passes posterior to ischial spine and sacrospinous ligament

  • Enters lesser sciatic foramen to enter perineum

  • Traverses pudendal (Alcock) canal on the medial surface of obturator internus muscle

Termination:

  • Ends by dividing into its terminal branches:

    • Perineal artery

    • Dorsal artery of the penis/clitoris

Branches

  • Inferior rectal artery

  • Perineal artery

  • Bulbourethral/bulb of vestibule branches

  • Urethral artery

  • Deep artery of penis/clitoris

  • Dorsal artery of penis/clitoris

Relations

  • Superiorly: Ischial spine, sacrospinous ligament

  • Inferiorly: Perineal muscles and ischiorectal fossa

  • Medially: Pudendal nerve, internal pudendal veins (neurovascular bundle)

  • Laterally: Obturator internus muscle and fascia (Alcock canal)

  • Anteriorly: Urogenital diaphragm structures

Function

  • Supplies blood to:

    • External genitalia (penis, clitoris)

    • Perineal skin and musculature

    • Anal canal and inferior rectum

    • Urethra and urogenital diaphragm

  • Supports erection via deep and dorsal penile/clitoral arteries

  • Provides vascular supply to perineal continence structures

Clinical Significance

  • Essential in surgeries such as hemorrhoidectomy, urethral reconstruction, and perineal flap procedures

  • Vulnerable during pelvic fractures and perineal trauma

  • Target vessel for arterial embolization in hemorrhage or tumors

  • Involved in erectile dysfunction if stenosed or injured

MRI Appearance

T1-weighted images:

  • Internal pudendal artery appears as a small dark flow-void within Alcock canal

  • Surrounding pelvic fat: bright reference signal

  • Arterial wall subtle and low in signal

T2-weighted images:

  • Flowing blood: dark flow-void

  • Vessel margin sharply defined in ischiorectal fossa fat

  • Distinguishable from pudendal nerve (slightly different course and thickness)

STIR:

  • Blood flow: dark signal

  • Fat suppression improves contrast between vessel and surrounding tissues

  • Vessel wall remains low signal

T1 Fat-Saturated Post-Contrast:

  • Lumen enhances brightly and uniformly

  • Vessel easily tracked through pelvic floor and Alcock canal

  • Enhancing course allows separation from pudendal nerve and veins

DWI (Diffusion Weighted Imaging):

  • Arterial lumen typically low signal due to flow

  • No diffusion restriction in a normal artery

  • Vessel outlines may be obscure on high-b-value images

CT Appearance

Non-Contrast CT:

  • Artery difficult to distinguish unless calcified

  • Appears as small soft-tissue density along ischial spine and pudendal canal

  • Surrounded by fat of the ischioanal fossa

Post-Contrast CT:

  • Brightly enhancing small artery along:

    • posterior ischial spine

    • lateral wall of ischioanal fossa

    • Alcock canal

MRI image

Internal pudendal artery male image 1

MRI image

Internal pudendal artery male image 2

MRI image

Internal pudendal artery