Cuneiform Bones
The cuneiform bones are three wedge-shaped tarsals that help maintain the medial foot arch.
The cuneiform bones are three wedge-shaped tarsal bones located in the midfoot between the navicular bone posteriorly and the bases of the first three metatarsals anteriorly. Named for their shape, these bones are the medial cuneiform, intermediate cuneiform, and lateral cuneiform, arranged from medial to lateral. Together, they contribute to the transverse and medial longitudinal arches of the foot and form an essential part of the tarsometatarsal and intercuneiform joints.
Structure
The cuneiforms are irregular, wedge-like bones with articular and non-articular surfaces. Each has a broad dorsal base and a narrower plantar apex, which contributes to the domed structure of the foot’s transverse arch. All three bones are composed of an outer cortical layer and inner cancellous bone to endure compressive and shear forces during locomotion.
1. Medial Cuneiform (First Cuneiform)
- Largest of the three
- Located on the medial side of the foot
- Wedge-shaped with broad medial surface
2. Intermediate Cuneiform (Second Cuneiform)
- Smallest of the cuneiforms
- Positioned between the medial and lateral cuneiforms
- Base directed dorsally, apex plantarly
3. Lateral Cuneiform (Third Cuneiform)
- Intermediate in size
- Located between the intermediate cuneiform medially and the cuboid laterally
- Contributes to the lateral portion of the midfoot arch
Location
The cuneiforms are situated in the distal row of the tarsal bones, forming a bridge between the navicular and the first three metatarsals. They lie deep to the dorsal fascia and between the plantar ligaments and tendons.
- Posterior: Navicular bone
- Anterior: First, second, and third metatarsal bases
- Medial: Medial cuneiform lies adjacent to the navicular tuberosity
- Lateral: Lateral cuneiform articulates with the cuboid
Function
- Stabilization: Provide a solid structural base for the medial foot and forefoot
- Force transmission: Transfer weight from the hindfoot to the forefoot
- Arch support: Help maintain the transverse and medial longitudinal arches of the foot
- Muscle leverage: Serve as points of origin or insertion for muscles that assist in dorsiflexion, plantarflexion, and inversion
Articulations
| Cuneiform | Articulating Bones | Joint Types |
|---|---|---|
| Medial cuneiform | Navicular, 1st and 2nd metatarsals, intermediate cuneiform | Synovial plane |
| Intermediate cuneiform | Navicular, medial and lateral cuneiforms, 2nd metatarsal | Synovial plane |
| Lateral cuneiform | Navicular, intermediate cuneiform, cuboid, 2nd and 3rd metatarsals | Synovial plane |
Ligament Attachments
The cuneiforms are interconnected and stabilized by numerous ligaments that contribute to midfoot integrity.
| Ligament | Attachment | Function |
|---|---|---|
| Intercuneiform ligaments | Between adjacent cuneiforms | Prevents splaying, maintains transverse arch |
| Dorsal and plantar tarsometatarsal ligaments | Cuneiforms to bases of metatarsals | Stabilize tarsometatarsal joints |
| Plantar cuneonavicular ligament | Navicular to medial and intermediate cuneiforms | Supports medial arch |
Muscle Attachments
Each cuneiform serves as an origin or insertion point for muscles involved in foot movement and stability.
- Tibialis anterior: Inserts onto medial cuneiform and base of the first metatarsal — dorsiflexes and inverts the foot
- Fibularis longus: Inserts onto medial cuneiform and first metatarsal — plantarflexes and everts the foot
- Tibialis posterior: Inserts into all three cuneiforms — inverts the foot and supports the arch
- Flexor hallucis brevis: Originates partly from the lateral cuneiform — flexes the great toe
Blood Supply
The cuneiforms receive blood supply from branches of the:
- Dorsalis pedis artery: Supplies dorsal aspects
- Medial plantar artery: Supplies the medial cuneiform and plantar surfaces
- Lateral plantar artery: Contributes to the lateral and plantar aspects
The vascularity is rich around the articular margins and ensures rapid remodeling, though traumatic disruption can still impair healing.
Nerve Supply
The cuneiform bones are innervated by articular branches of the:
- Deep fibular (peroneal) nerve: Supplies dorsal surface sensation and proprioception
- Medial plantar nerve: Innervates medial and plantar regions
- Lateral plantar nerve: Innervates lateral cuneiform and adjacent plantar structures
Ossification
- Medial cuneiform: Ossification center appears at ~2 years
- Intermediate cuneiform: Appears at ~3 years
- Lateral cuneiform: Appears at ~1 year
All ossify from a single center and complete fusion by late childhood. Delay in ossification is not uncommon and should not be confused with pathology unless symptomatic.
Clinical Significance
- Lisfranc injury: Disruption of tarsometatarsal joints, often involving the cuneiform–metatarsal articulation; causes midfoot instability and pain
- Stress fractures: Rare but possible in athletes or military recruits; intermediate cuneiform is the most commonly affected
- Midfoot arthritis: Degeneration may involve intercuneiform and tarsometatarsal joints, resulting in stiffness and dorsomedial foot pain
- Coalitions: Abnormal fusion between cuneiforms or other tarsal bones, leading to restricted motion
- Flatfoot deformity: Collapse of the medial arch can strain the medial cuneiform’s articulations with the navicular and first metatarsal
Imaging
- X-ray: Weight-bearing AP, oblique, and lateral views are used to assess alignment and joint spacing
- CT scan: Useful in assessing complex fractures or tarsometatarsal dislocations
- MRI: Best for identifying stress injuries, arthritis, or soft tissue pathologies involving surrounding ligaments
- Ultrasound: May be used for dynamic evaluation of adjacent tendons like tibialis anterior or posterior
Last updated on May 21, 2025
