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Fourth toe

The fourth toe (fourth digit of the foot) is the lateral neighbor of the third toe and medial to the fifth (little) toe. It plays a supportive role in balance, propulsion, and weight distribution during gait. Structurally, it consists of three phalanges—proximal, middle, and distal—articulating with the fourth metatarsal through the metatarsophalangeal (MTP) joint.

The toe’s stability and mobility depend on a complex arrangement of bones, joints, tendons, muscles, ligaments, and neurovascular structures. Its flexion and extension are primarily controlled by long and short digital flexors and extensors, contributing to smooth push-off and ground adaptation during walking or running.

Synonyms

  • Fourth digit of the foot

  • Fourth ray of the foot

  • Fourth phalangeal segment

Components and Structure

  • Bones: Proximal, middle, and distal phalanges; articulate proximally with the head of the fourth metatarsal

  • Joints:

    • Metatarsophalangeal (MTP) joint – between the fourth metatarsal head and proximal phalanx

    • Proximal interphalangeal (PIP) joint – between proximal and middle phalanges

    • Distal interphalangeal (DIP) joint – between middle and distal phalanges

  • Ligaments: Plantar and collateral ligaments reinforce the MTP, PIP, and DIP joints

Muscles Acting on the Fourth Toe

Extrinsic Muscles:

  • Extensor digitorum longus: Extends toes 2–5

  • Flexor digitorum longus: Flexes distal phalanges of toes 2–5

  • Extensor digitorum brevis: Assists in extension of the middle phalanx

Intrinsic Muscles:

  • Lumbrical (third lumbrical): Flexes MTP joint, extends PIP and DIP joints

  • Plantar interossei (third interosseous): Adducts the fourth toe toward the midline (second toe)

  • Dorsal interossei: Abducts adjacent toes; the fourth toe is acted upon by the third and fourth dorsal interossei

Tendon Attachments

  • Extensor tendons: Dorsal surface; insert onto middle and distal phalanges via dorsal digital expansions

  • Flexor tendons: Plantar surface; flexor digitorum longus inserts onto distal phalanx, and flexor digitorum brevis onto middle phalanx

  • Lumbrical tendon: Inserts medially into dorsal expansion, assisting flexion-extension balance

Relations

  • Dorsally: Extensor tendons and dorsal digital veins

  • Plantar aspect: Flexor tendons, digital arteries, and nerves

  • Medially: Third toe

  • Laterally: Fifth toe

  • Deep structures: Digital branches of plantar nerves and arteries beneath the tendons

Nerve Supply

  • Medial plantar nerve: Supplies the first lumbrical (adjacent to the second toe)

  • Lateral plantar nerve: Supplies interossei, lumbricals to fourth toe, and plantar skin

  • Superficial peroneal nerve: Dorsal digital branches to dorsal skin of the fourth toe

Arterial Supply

  • Plantar digital arteries (branches of plantar metatarsal arteries from the deep plantar arch)

  • Dorsal digital arteries (branches of dorsal metatarsal arteries from dorsalis pedis artery)

Venous Drainage

  • Dorsal venous network drains into the great saphenous and small saphenous veins

  • Plantar venous plexus drains medially into the posterior tibial vein

Function

  • Flexion and extension: Controlled by flexor and extensor tendons for gait propulsion

  • Balance and stability: Maintains equilibrium during stance phase

  • Weight distribution: Helps share load during toe-off with third and fifth toes

  • Proprioception: Contains sensory feedback receptors aiding posture control

Clinical Significance

  • Fractures: Common in athletes and crush injuries; often involve distal or middle phalanges

  • Dislocations: Usually at PIP or DIP joints

  • Hammer toe deformity: Flexion deformity of the PIP joint due to muscular imbalance

  • Claw toe: Hyperextension at MTP with flexion at PIP and DIP, common in neuropathic conditions

  • Tendon or ligament injury: From repetitive trauma or ill-fitting footwear

  • Vascular compromise: Ischemic ulcers may develop at distal pulp in diabetes

  • Surgical importance: Critical in digital deformity correction and reconstructive procedures

MRI Appearance

  • T1-weighted images:

    • Normal phalangeal bone marrow: intermediate-to-bright signal

    • Cortical bone: dark (low signal)

    • Muscles and tendons: intermediate signal intensity

    • Fat pads: bright (high signal)

    • Joint capsules and ligaments: low signal

  • T2-weighted images:

    • Normal bone marrow: intermediate-to-bright signal depending on fat content

    • Muscles: darker than on T1, intermediate signal

    • Tendons and ligaments: dark (low signal)

    • Edema or inflammation: bright hyperintense signal

    • Synovial fluid in joints: high signal

  • STIR:

    • Normal muscles: intermediate-to-dark signal

    • Bone marrow edema or inflammation: bright hyperintense areas

    • Soft-tissue swelling or infection: markedly bright signal

    • Tendons remain dark unless injured

  • Proton Density Fat-Saturated (PD FS):

    • Normal muscles: intermediate-to-dark signal intensity

    • Pathology: bright signal in tendons or muscles indicating tear, strain, or edema

    • Excellent for detecting soft-tissue injury, tendon pathology, or joint effusion

  • T1 Fat-Sat Post-Contrast:

    • Normal muscle: uniform mild enhancement

    • Inflamed tendon or soft tissue: focal enhancement

    • Infection or tumor: heterogeneous, often nodular enhancement

    • Postoperative or inflammatory changes: ring-like or diffuse enhancement patterns

CT Appearance

Non-Contrast CT:

  • Bones: well visualized, cortical margins sharply defined

  • Muscles: homogeneous soft-tissue density

  • Tendons and ligaments: linear soft-tissue structures of slightly higher density

  • Joint spaces: visible with thin interposed low-density cartilage

  • Fractures: easily detected with cortical disruption and surrounding soft-tissue swelling

Post-Contrast CT (standard):

  • Muscles: homogeneous enhancement

  • Inflamed tissues or infection: focal or diffuse enhancement

  • Vascular structures and small digital arteries: enhance brightly

  • Useful in evaluating osteomyelitis, vascular lesions, and complex fractures

MRI image

fourth toe of foot axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

CT image

fourth toe CT coronal image