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First metatarsal bone

The first metatarsal bone is the shortest and thickest of all the metatarsals, forming the structural base of the great toe. It plays a crucial role in weight bearing, propulsion during gait, and stability of the medial longitudinal arch. The bone articulates proximally with the medial cuneiform and distally with the base of the proximal phalanx of the hallux, incorporating two sesamoid bones within its plantar articular surface.

It provides attachment to key tendons and ligaments responsible for toe flexion, extension, and stabilization of the first ray, making it functionally vital in walking, running, and balance.

Synonyms

  • First metatarsal of foot

  • Metatarsal I

  • Great toe metatarsal

Location and Articulations

  • Location: Medial aspect of the forefoot, forming the first ray along with the medial cuneiform and hallux

  • Proximal articulation: Medial cuneiform at the first tarsometatarsal joint

  • Distal articulation: Base of the proximal phalanx of the hallux

  • Plantar articulation: Two sesamoid bones (medial and lateral) within the tendon of flexor hallucis brevis

Surfaces and Features

  • Base (proximal end): Kidney-shaped, articulating with medial cuneiform; gives attachment to strong plantar and dorsal ligaments

  • Shaft: Short, thick, and slightly concave on its plantar aspect

  • Head (distal end): Convex and bears articular facets for proximal phalanx and sesamoids

  • Plantar surface: Contains grooves for sesamoid bones and tendinous attachments

Attachments

  • Tendons:

    • Tibialis anterior: Inserts on medial surface of base

    • Fibularis (peroneus) longus: Inserts on lateral base (together with medial cuneiform)

    • First dorsal interosseous: Originates from medial side of shaft

    • Flexor hallucis brevis: Inserts via two tendons, enclosing the sesamoid bones on the plantar surface

  • Ligaments:

    • Dorsal and plantar tarsometatarsal ligaments

    • Deep transverse metatarsal ligament connecting adjacent metatarsal heads

Relations

  • Medially: Medial cuneiform and skin of medial foot

  • Laterally: Second metatarsal base and intermetatarsal joint capsule

  • Superiorly: Extensor hallucis longus tendon crossing the dorsum

  • Inferiorly: Flexor hallucis brevis, sesamoid bones, and plantar fascia

Arterial Supply

  • Dorsalis pedis artery and its first dorsal metatarsal branch

  • Medial plantar artery supplies plantar aspect

  • Nutrient branches enter at midshaft and metaphyseal regions

Venous Drainage

  • Drains via dorsal venous arch and plantar venous network, ultimately into the great saphenous and posterior tibial veins

Nerve Supply

  • Dorsal digital branch of deep fibular (peroneal) nerve to dorsal surface

  • Medial plantar nerve supplies plantar aspect and adjacent soft tissues

Function

  • Weight bearing: Bears significant load during push-off phase of gait

  • Propulsion: Acts as the primary lever during toe-off

  • Arch support: Contributes to medial longitudinal arch stability

  • Balance: Maintains forefoot alignment and medial support during ambulation

Clinical Significance

  • Fractures: Common in athletes and dancers (stress or traumatic)

  • Bunion (hallux valgus): Deformity from medial deviation of metatarsal head

  • Sesamoiditis: Inflammation or stress around sesamoids of the plantar head

  • Arthritis: Degenerative changes at first metatarsophalangeal (MTP) or tarsometatarsal (TMT) joints

  • Imaging role: MRI and CT essential for stress injuries, nonunions, and complex deformities

MRI Appearance

  • T1-weighted images:

    • Normal marrow: bright signal, reflecting fatty content

    • Cortex: dark (low signal) with sharp margins

    • Fracture line: low-signal linear defect through bright marrow

    • Bone marrow edema or infection: low signal replacing normal brightness

    • Tendon attachments (tibialis anterior, peroneus longus): dark fibrous insertions on base

  • T2-weighted images:

    • Marrow: bright signal intensity, varying with fat composition

    • Cortex: dark continuous rim

    • Fractures or edema: bright hyperintense signal in medullary or subcortical regions

    • Degenerative cysts or inflammation: focal bright areas near joint surfaces

  • STIR (Short Tau Inversion Recovery):

    • Normal marrow: dark signal due to fat suppression

    • Pathology (stress fracture, contusion, infection): bright hyperintense signal replacing normal fat

    • Excellent for early detection of bone stress injuries

  • Proton Density Fat-Saturated (PD FS):

    • Normal marrow: dark (fat-suppressed)

    • Abnormal: bright signal in areas of edema, fracture, or osteomyelitis

    • Clear visualization of periosteal reaction and soft-tissue edema

  • T1 Fat-Sat Post-Contrast:

    • Normal bone: mild uniform enhancement

    • Inflammation or infection: heterogeneous enhancement

    • Necrotic or sclerotic areas: minimal or no enhancement

CT Appearance

Non-Contrast CT:

  • Demonstrates dense cortical margins and trabecular structure clearly

  • Useful for identifying fractures, cortical thickening, sclerosis, or erosions

  • Stress fractures: subtle linear lucencies or sclerotic bands

  • Degenerative changes: joint space narrowing, osteophytes, subchondral cysts

  • Accessory sesamoid variants well visualized

Post-Contrast CT (standard):

  • Provides minimal additional information for bone

  • May demonstrate enhancement in regions of infection or inflammatory soft-tissue changes

  • Excellent for evaluating bone integrity and surgical planning

CT VRT 3D image

First metatarsal bone ct 3d vrt image

MRI image

First metatarsal bone axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI image

First metatarsal bone axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00001

MRI image

First metatarsal bone sah cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

CT image

First metatarsal bone ct sagittal image