Medial Plantar Artery: Anatomy, Relations, Function, Clinical & Imaging Features

Topic

Medial plantar artery

The medial plantar artery is the smaller of the two terminal branches of the posterior tibial artery, arising beneath the flexor retinaculum at the medial side of the ankle. It supplies the medial aspect of the sole of the foot, including the abductor hallucis, flexor hallucis brevis, and skin of the medial plantar surface.

Although smaller than the lateral plantar artery, it plays a critical role in maintaining perfusion of the medial plantar compartment and contributes to the superficial plantar arterial arch.

Origin, Course, and Termination

Origin: From the posterior tibial artery beneath the flexor retinaculum, deep to the abductor hallucis muscle at the level of the ankle.
Course: Runs forward between the abductor hallucis and flexor digitorum brevis, giving branches to these muscles and to the overlying skin.
- The superficial branch supplies the medial skin of the sole and forms the superficial plantar arch with the lateral plantar artery.
- The deep branch supplies the hallucal muscles and communicates with the lateral plantar artery near the base of the first metatarsal.
Termination: Divides into superficial and deep branches at the midfoot region, contributing to digital arteries and the plantar arch.

Relations

Anteriorly: Flexor hallucis brevis, first metatarsal base
Posteriorly: Abductor hallucis muscle
Medially: Plantar aponeurosis
Laterally: Lateral plantar artery and deep plantar arch
Superiorly: Posterior tibial nerve (medial plantar branch in close proximity)

Branches

Muscular branches: Supply abductor hallucis, flexor hallucis brevis, and flexor digitorum brevis
Cutaneous branches: To medial plantar skin and great toe
Superficial branch: Contributes to the superficial plantar arch
Deep branch: Joins the lateral plantar artery to complete the plantar arterial arch

Function

Arterial supply: Provides blood to the medial plantar compartment, great toe, and medial sole skin
Anastomoses: Forms critical vascular communications with the lateral plantar and dorsalis pedis arteries
Supportive role: Maintains perfusion during plantar flexion and weight-bearing, ensuring collateral flow around the foot

Clinical Significance

Arterial insufficiency: Compromised flow may lead to ischemic pain or plantar ulceration in diabetes or peripheral vascular disease
Trauma: Injury during foot surgery or lacerations may cause bleeding or ischemia of the medial sole
Entrapment: Can be compressed under the abductor hallucis in tarsal tunnel syndrome, contributing to plantar pain
Imaging importance: Evaluated in cases of plantar ischemia, arterial injury, aneurysm, or bypass planning

MRI Appearance

T1-weighted images:
- Artery appears as a tubular low-signal structure within the fat of the medial plantar region.
- Surrounding fat and soft tissues appear hyperintense.
- May show flow voids due to rapid blood flow.
T2-weighted images:
- Flowing blood produces a signal void (dark linear structure).
- Adjacent muscles (abductor hallucis, flexor digitorum brevis) show intermediate signal intensity.
- Thrombus or slow flow can appear mildly hyperintense within the arterial lumen.
STIR / PD FS sequences:
- Vessel walls and perivascular soft tissues are well defined.
- Hyperintense perivascular signal may indicate inflammation, edema, or entrapment.
T1 Fat-Sat Post-Contrast (axial):
- Enhances sharply as a bright linear or rounded structure depending on the section plane.
- Confirms patency and course of the medial plantar artery.
- Post-traumatic or postsurgical hyperemia enhances perivascular tissues.

Contrast-Enhanced MRA (Magnetic Resonance Angiography)

Normal findings:
- The medial plantar artery enhances as a fine, continuous vessel extending from the posterior tibial artery beneath the abductor hallucis.
- Appears as a smooth, bright line with uniform caliber and continuity into the plantar arch.
Pathologic findings:
- Occlusion: Segmental loss of enhancement or cutoff.
- Stenosis: Narrowing with distal reduced enhancement.
- Collateral formation: Small tortuous branches near chronic occlusions.
- Post-traumatic pseudoaneurysm: Focal contrast-filled outpouching adjacent to artery.

CTA (Computed Tomography Angiography)

Normal appearance:
- Visualized as a small-caliber enhancing artery along the medial aspect of the plantar foot.
- Origin from the posterior tibial artery visible with high spatial resolution.
- Surrounding fat and muscles (abductor hallucis, flexor hallucis brevis) clearly outlined.
Pathologic features:
- Atherosclerosis: Calcified plaques or luminal narrowing near origin.
- Trauma: Irregular margins, extravasation, or pseudoaneurysm formation.
- Occlusion: Absence of contrast opacification beyond lesion site.
- Post-surgical evaluation: Assessment of bypass graft or flap perfusion.