Lateral Plantar Artery: Anatomy, Course, Branches, Function, MRI & CTA

Topic

Lateral plantar artery

The lateral plantar artery is the larger terminal branch of the posterior tibial artery, supplying most of the plantar surface of the foot. It runs obliquely across the sole, forming the deep plantar arch, which provides the major arterial supply to the digits and plantar musculature.

It plays a vital role in plantar perfusion, digital blood supply, and anastomotic connection with the dorsalis pedis artery. Because of its deep position and tortuous course, the lateral plantar artery is clinically important in cases of ischemia, trauma, diabetic foot disease, and vascular reconstruction.

Synonyms

External plantar artery
Lateral terminal branch of posterior tibial artery

Origin, Course, and Termination

Origin: Arises from the posterior tibial artery deep to the flexor retinaculum, posterior to the medial malleolus.
Course:
- Passes anteriorly and laterally, deep to the abductor hallucis muscle.
- Continues between the flexor digitorum brevis (superficially) and quadratus plantae (deeply).
- Runs obliquely across the sole toward the base of the fifth metatarsal, then turns medially to form the deep plantar arch.
Termination: Unites with the deep plantar branch of the dorsalis pedis artery, completing the plantar arterial arch near the bases of the first and second metatarsals.

Branches

Muscular branches: To abductor digiti minimi, flexor digitorum brevis, and quadratus plantae.
Cutaneous branches: Supply skin of the lateral sole.
Digital branches: Form plantar metatarsal arteries that bifurcate into plantar digital arteries supplying the toes.
Anastomotic branches: Join with medial plantar and dorsalis pedis arteries to form a collateral network.

Relations

Superiorly: Flexor digitorum brevis, quadratus plantae
Inferiorly: Plantar aponeurosis
Medially: Medial plantar artery and nerve
Laterally: Abductor digiti minimi and fifth metatarsal base
Accompanied by: Lateral plantar vein and lateral plantar nerve along most of its course

Function

Primary blood supply to the lateral and central plantar regions of the foot
Forms deep plantar arch supplying toes and plantar muscles
Provides collateral circulation via connections with dorsalis pedis artery
Maintains perfusion during weight bearing and stance phase of gait

Arterial Territories Supplied

Lateral sole of the foot
All interosseous muscles
Lateral three and a half toes (via plantar digital arteries)
Quadratus plantae, flexor digitorum brevis, and abductor digiti minimi muscles

Clinical Significance

Peripheral vascular disease: Common site for atherosclerotic narrowing in diabetic and ischemic foot
Trauma: Lacerations or crush injuries may compromise digital circulation
Flap surgery: Used in reconstructive procedures for plantar flaps and toe grafts
Aneurysm/aneurysmal dilatation: Rare but may cause localized swelling or pain
Imaging importance: Key vessel in assessment of plantar perfusion and pedal arch patency

MRI Appearance

T1-weighted images:
- Normal artery appears as flow void (signal loss) due to rapid blood flow.
- In slow or turbulent flow, partial intraluminal signal may appear.
- Perivascular fat gives a bright rim outlining the vessel in the plantar soft tissues.
T2-weighted images:
- Vessel lumen shows flow void or low signal.
- Surrounding edema, inflammation, or soft-tissue swelling appears hyperintense.
- Arterial wall thickening or mural thrombus may produce intermediate signal intensity.
STIR:
- Normal artery: dark flow void.
- Pathologic states (vasculitis, thrombosis): bright signal in perivascular soft tissues.
Proton Density Fat-Saturated (PD FS):
- Normal lumen: flow void.
- Occlusion or thrombosis: loss of flow void and mild bright signal from clot.
T1 Fat-Sat Post-Contrast (Normal Axial Post-Contrast):
- Artery enhances brightly and sharply, contrasting with non-enhancing veins and muscles.
- Wall irregularities or partial filling defects suggest stenosis, atheroma, or thrombus.
- Adjacent soft tissue enhancement may indicate inflammation or infection (diabetic foot).
Contrast-Enhanced MRA (CE-MRA):
- Demonstrates high-signal enhancement of the lateral plantar artery and plantar arch.
- Enables visualization of continuity, branching, and perfusion defects.
- Best sequence for detecting stenosis, occlusion, aneurysm, or collateral flow patterns.
- Dynamic contrast timing allows assessment of arterial runoff and pedal arch integrity.

CT Appearance

Non-Contrast CT:

Artery seen as a faint tubular structure of soft-tissue density within plantar fat.
May show arterial calcifications in chronic atherosclerosis.
Not well delineated without contrast enhancement.

Post-Contrast CT (CT Angiography – CTA):

Lateral plantar artery enhances brightly, forming a visible deep plantar arch.
Provides excellent depiction of lumen caliber, course, and branching pattern.
Detects stenosis, occlusion, or aneurysm and allows measurement of plaque burden.
CTA can differentiate between vascular vs. soft-tissue pathology in diabetic foot or trauma.
3D reconstructions show plantar arch continuity and collateral circulation with dorsalis pedis.