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Proximal phalanx of foot

The proximal phalanx of the foot is the first bone of each toe, located distal to the metatarsal heads and proximal to the middle or distal phalanges. Each phalanx forms part of the toe’s skeletal framework, contributing to stability, balance, and propulsion during walking.

All five toes have a proximal phalanx, but the hallux (great toe) is unique in having only two phalanges—a proximal and a distal one—while the other toes have three (proximal, middle, distal). The proximal phalanges articulate proximally with the metatarsal heads to form the metatarsophalangeal (MTP) joints and distally with the middle or distal phalanges at the interphalangeal joints.

Synonyms

  • Basal phalanx of toe

  • First phalanx of toe

  • Proximal digital bone of foot

Location and Structure

  • Number: Five in total—one for each toe

  • Shape: Elongated tubular bone with a base, shaft, and head

  • Base: Expanded and concave proximally for articulation with metatarsal head

  • Shaft: Cylindrical and slightly curved

  • Head: Distal convex surface articulating with middle or distal phalanx

  • Marrow composition: Cancellous bone with active red marrow, surrounded by compact cortical bone

Attachments

  • Proximal base: Capsule of metatarsophalangeal joint and plantar ligaments

  • Sides: Collateral ligaments of MTP and interphalangeal joints

  • Plantar surface: Flexor tendons (flexor digitorum brevis and longus) and plantar plates

  • Dorsal surface: Extensor tendons (extensor digitorum longus and brevis)

  • Great toe attachments: Flexor hallucis brevis, flexor hallucis longus, and extensor hallucis longus tendons insert around the base

Relations

  • Proximal: Metatarsal head

  • Distal: Middle or distal phalanx (depending on toe)

  • Dorsally: Extensor tendons and dorsal digital nerves and veins

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

Arterial Supply

  • Plantar digital arteries from medial and lateral plantar arteries

  • Dorsal digital arteries from the dorsal pedis artery

Venous Drainage

  • Dorsal digital veins drain into dorsal venous arch

  • Plantar digital veins drain into medial and lateral plantar veins

Nerve Supply

  • Digital branches of medial and lateral plantar nerves (from tibial nerve)

  • Dorsal digital nerves from superficial peroneal nerve

Function

  • Toe flexion and extension: Acts as a lever for flexor and extensor tendons during gait

  • Stability: Maintains alignment of toes and supports body balance

  • Propulsion: Facilitates push-off phase in walking and running

  • Load distribution: Helps distribute weight across forefoot and toes

Clinical Significance

  • Fractures: Common in sports, crush injuries, or stubbing trauma

  • Stress injuries: Repetitive microtrauma may cause bone marrow edema or stress reaction

  • Arthritis: Degenerative or inflammatory arthritis may affect MTP or interphalangeal joints

  • Infections: Osteomyelitis may involve marrow cavity, especially in diabetics

  • Tumors and cysts: Rarely involve phalanges but can alter marrow signal on MRI

MRI Appearance

  • T1-weighted images:

    • Bone cortex: uniformly low signal (dark line)

    • Marrow cavity: bright signal due to fatty marrow content

    • Cortico-medullary differentiation clearly visible

    • Fracture or infection: focal low-signal disruption of cortical continuity or marrow replacement

  • T2-weighted images:

    • Marrow: remains bright (high signal) from fat content

    • Cortex: persistently dark (low signal)

    • Pathology: marrow edema or osteomyelitis shows increased bright signal; cortical fracture lines appear dark

    • Cartilage at articular surfaces: intermediate-to-high signal depending on hydration

  • STIR:

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

    • Pathology: hyperintense (bright) in bone marrow edema, infection, or tumor

  • Proton Density Fat-Saturated (PD FS):

    • Normal marrow: intermediate-to-dark signal

    • Bone injury or inflammation: bright hyperintensity indicating marrow fluid or edema

    • Excellent for subtle stress reactions or early osteitis

  • T1 Fat-Sat Post-Contrast:

    • Normal bone: homogeneous mild enhancement

    • Osteomyelitis or fracture: intense or patchy marrow enhancement

    • Synovitis: enhancing soft tissue around MTP joint

CT Appearance

Non-Contrast CT:

  • Bone cortex: dense, well-defined margin

  • Trabecular bone: fine internal architecture visible

  • Marrow cavity: hypodense relative to cortex

  • Detects fractures, deformities, cortical erosion, or osteophyte formation

Post-Contrast CT (standard):

  • Enhances surrounding soft tissues, not the bone marrow itself

  • Useful for evaluating osteomyelitis, periosteal reaction, and soft-tissue abscesses

MRI image

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MRI image

proximal phalanx foot coronal cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00001

MRI image

proximal phalanx foot sag cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

CT image

proximal phalanx of foot ct sag image