Navicular Bone

The navicular bone is a boat-shaped tarsal bone located on the medial side of the midfoot. It acts as a keystone in the medial longitudinal arch and plays a central role in foot structure and mobility. It articulates with the talus posteriorly, the three cuneiforms anteriorly, and sometimes the cuboid laterally. The navicular also serves as the primary insertion point for the tibialis posterior tendon, contributing significantly to dynamic arch support and foot inversion.

Structure

The navicular is a small, oblong bone with a concave posterior surface and three smaller convex anterior facets. Its medial surface features a prominent tuberosity that serves as an important muscular attachment site. The bone is compact externally, with cancellous bone internally, adapted to distribute forces in the midfoot during weight-bearing and gait.

Surfaces and Features

• Posterior surface: Concave and oval, articulates with the head of the talus to form the talonavicular joint.
• Anterior surface: Presents three small facets for articulation with the medial, intermediate, and lateral cuneiform bones.
• Medial surface: Prominent navicular tuberosity — palpable and clinically relevant — provides insertion for tibialis posterior.
• Lateral surface: May articulate with the cuboid (in ~50% of individuals); otherwise non-articular.
• Dorsal and plantar surfaces: Roughened for ligamentous and fascial attachments; the plantar surface is associated with arch-supporting structures.

Location

The navicular lies medially in the midfoot between the talus and the three cuneiform bones. It is situated distal to the talar head and proximal to the cuneiforms, and forms the central component of the medial longitudinal arch.

• Posterior: Head of the talus
• Anterior: Medial, intermediate, and lateral cuneiforms
• Medial: Navicular tuberosity (subcutaneous and palpable)
• Lateral: Occasionally articulates with the cuboid bone

Function

• Keystone of the medial arch: Supports and maintains the integrity of the medial longitudinal arch of the foot
• Articulation and mobility: Part of the talonavicular joint, which enables inversion and eversion during gait
• Force transmission: Transmits forces from the hindfoot to the forefoot during walking and running

Articulations

The navicular forms five or six articulations:

Bone	Joint	Joint Type
Talus	Talonavicular joint	Synovial ball-and-socket
Medial cuneiform	Naviculocuneiform joint	Synovial plane
Intermediate cuneiform	Naviculocuneiform joint	Synovial plane
Lateral cuneiform	Naviculocuneiform joint	Synovial plane
Cuboid (variable)	Naviculocuboid articulation	Synovial plane (if present)

Ligament Attachments

Several key ligaments attach to the navicular, providing joint stability and contributing to arch support.

Ligament	Attachment	Function
Plantar calcaneonavicular (spring) ligament	From sustentaculum tali (calcaneus) to navicular tuberosity	Supports head of talus and medial longitudinal arch
Dorsal talonavicular ligament	Neck of talus to dorsal navicular	Stabilizes talonavicular joint
Interosseous ligament	Between navicular and cuneiforms	Prevents joint separation
Plantar ligaments	Navicular to cuneiforms and cuboid (if articulated)	Reinforce plantar arch

Muscle Attachments

The navicular serves as the main insertion point for the tendon of the tibialis posterior muscle, which is critical for arch maintenance and foot inversion.

• Tibialis posterior: Inserts primarily on the navicular tuberosity and spreads fibers to the cuneiforms and metatarsals

Occasionally, a small portion of the flexor hallucis brevis or other intrinsic plantar muscles may have indirect attachments via surrounding fascia, but these are not primary insertions.

Blood Supply

The navicular is supplied by branches from the:

• Dorsalis pedis artery: Supplies dorsal and medial aspects
• Medial plantar artery: Contributes to the plantar surface
• Posterior tibial artery: Provides arterial branches near the tuberosity and talonavicular joint

Because of its articular cartilage coverage and minimal muscular attachments, vascularity is limited. This makes the navicular susceptible to avascular necrosis, particularly in its central zone.

Nerve Supply

Innervation is provided by:

• Medial plantar nerve: Supplies medial and plantar aspects
• Deep fibular (peroneal) nerve: Supplies dorsal surface
• Saphenous nerve: Provides cutaneous sensation to overlying medial skin

Ossification

The navicular is the last tarsal bone to ossify. It ossifies from a single center, which appears postnatally, typically around 3 years of age in girls and 4 years in boys.

• Ossification center appears: ~3–4 years of age
• No secondary center: Usually ossifies entirely from a single center

Delayed ossification is a normal variant but may be mistaken for pathology in pediatric radiographs.

Clinical Significance

• Navicular fracture: Can result from direct trauma or repetitive stress (e.g., runners, jumpers). Stress fractures are common and often difficult to detect early on plain films.
• Avascular necrosis (Köhler disease): Occurs in children and leads to sclerosis and flattening of the navicular. Usually self-limiting.
• Accessory navicular bone: A common anatomical variant (~10–15% of population), located medial to the tuberosity. Can be asymptomatic or cause medial foot pain, especially in adolescents.
• Tibialis posterior dysfunction: May cause medial arch collapse due to failure of support at the navicular insertion.
• Midfoot arthritis: Naviculocuneiform joints are often involved in midfoot degenerative arthritis.

Imaging

• X-ray: AP, lateral, and oblique views reveal fracture, accessory navicular, or sclerosis
• MRI: Best for evaluating stress reactions, bone marrow edema, AVN, or tibialis posterior tendon pathology
• CT scan: Useful in fracture evaluation or surgical planning
• Ultrasound: Can assess tibialis posterior tendon insertion near the tuberosity