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Distal phalanx of great toe

The distal phalanx of the great toe (hallux) is the terminal bone of the first ray of the foot. It provides structural support for the nail bed, serves as the insertion site for the extensor and flexor tendons, and plays a crucial role in toe push-off, balance, and propulsion during gait.

It is short, thick, and dorsoventrally flattened, designed to bear high axial loads during weight-bearing. The bone contains a rich cancellous marrow cavity, which exhibits bright signal intensity on both T1- and T2-weighted MRI images, reflecting its fatty marrow composition.

Synonyms

  • Terminal phalanx of the hallux

  • Distal phalanx of the first toe

  • Ungual phalanx of the great toe

Location and General Features

  • Forms the distal component of the first toe, articulating proximally with the proximal phalanx of the hallux via the interphalangeal joint

  • Broad and flattened dorsally to support the nail bed

  • Plantar surface forms the tuberosity for tendon attachment

  • Compact cortex surrounds a central trabecular marrow cavity

Articulations

  • Proximal articulation: Interphalangeal joint with the proximal phalanx of the hallux

  • Distal surface: Provides support for soft-tissue pad and nail matrix

Tendon and Ligament Attachments

  • Flexor hallucis longus tendon: Inserts into the plantar base of the distal phalanx, acting as the primary flexor of the great toe

  • Extensor hallucis longus tendon: Inserts onto the dorsal surface of the distal phalanx, providing extension of the great toe

  • Collateral ligaments: Strengthen the sides of the interphalangeal joint

  • Plantar plate: Supports the joint capsule on the plantar aspect

Relations

  • Dorsally: Nail bed and nail matrix

  • Plantar aspect: Flexor hallucis longus tendon and fibrofatty toe pad

  • Proximally: Proximal phalanx of the hallux and interphalangeal joint capsule

  • Distally: Soft tissues of the toe tip and subungual region

Arterial Supply

  • Plantar digital branches of the medial plantar artery (from posterior tibial artery)

  • Dorsal digital arteries from the dorsalis pedis artery

Venous Drainage

  • Dorsal digital veins drain into the dorsal venous arch

  • Plantar venous network drains into the medial plantar and posterior tibial veins

Nerve Supply

  • Plantar digital branch of the medial plantar nerve (sensory)

  • Dorsal digital nerve from deep fibular nerve (sensory to dorsal aspect of distal phalanx and nail bed)

Function

  • Support: Provides structural support for the nail bed and distal soft tissues

  • Flexion and extension: Acts as lever arm for FHL (flexion) and EHL (extension) during toe motion

  • Propulsion: Transmits forces during push-off phase of gait

  • Stability: Aids balance and maintains contact with the ground during terminal stance

Clinical Significance

  • Fractures: Commonly result from crush or stubbing injuries; may involve nail bed trauma

  • Osteomyelitis: Frequent site of infection secondary to ulceration or trauma in diabetics

  • Enthesopathy: Chronic stress at flexor or extensor insertion sites

  • Nail disorders: Subungual hematoma or infection may affect dorsal cortex

  • Imaging role: MRI essential for marrow pathology; CT best for cortical evaluation

MRI Appearance

  • T1-weighted images:

    • Bone cortex: low signal (dark rim)

    • Bone marrow: bright high signal due to fatty content

    • Tendon insertions: low signal linear bands on dorsal and plantar aspects

    • Fracture or infection: localized low-signal line or patch replacing bright marrow

  • T2-weighted images:

    • Bone cortex: dark

    • Marrow: bright, reflecting fat and trabecular pattern

    • Pathology: focal hyperintense signal in infection or marrow edema

    • Periosteal reaction or soft-tissue edema appears as surrounding bright regions

  • STIR:

    • Normal marrow: intermediate to dark signal (fat-suppressed appearance)

    • Edema, infection, or trauma: bright hyperintense areas replacing marrow fat

  • Proton Density Fat-Saturated (PD FS):

    • Normal marrow: intermediate-to-dark, homogeneous signal

    • Pathology: focal bright hyperintense areas with cortical irregularity or soft-tissue swelling

  • T1 Fat-Sat Post-Contrast:

    • Normal marrow: uniform mild enhancement

    • Osteomyelitis or inflammation: intense heterogeneous enhancement

    • Abscess: peripheral rim enhancement with central low signal

CT Appearance

Non-Contrast CT:

  • Bone cortex: dense, well-defined outline of the distal phalanx

  • Marrow cavity: low attenuation center (fat)

  • Fractures: linear cortical disruption or comminution

  • Osteomyelitis: cortical destruction, periosteal reaction, or trabecular irregularity

Post-Contrast CT (standard):

  • Normal bone: uniform enhancement of marrow cavity

  • Inflammatory or infectious changes: focal enhancement with soft-tissue stranding

  • Excellent for assessing fractures, sequestra, or cortical erosions

MRI image

Distal phalanx of great toe foot coronal cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI image

Distal phalanx of great toe foot sagittal cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

CT image

Distal Phalanx of the Great Toe ct sag image