Navicular (Foot)
Os Naviculare
location_on Medial side of the midfoot, between the talus and the three cuneiform bones
The navicular is a boat-shaped bone on the medial side of the foot, situated between the talus posteriorly and the three cuneiform bones anteriorly. It is a keystone of the medial longitudinal arch of the foot and the insertion point for the tibialis posterior tendon, the primary dynamic stabilizer of the arch. The navicular has a relatively poor blood supply, making it susceptible to stress fractures with delayed healing.
Key Anatomical Features
- Navicular tuberosity on the medial surface is palpable and receives the tibialis posterior tendon
- Proximal surface is concave for articulation with the talar head
- Distal surface has three facets for the medial, intermediate, and lateral cuneiforms
- Keystone of the medial longitudinal arch of the foot
- Accessory navicular (os tibiale externum) is a common variant present in 10-14% of people
Muscle Attachments
| Muscle | Attachment | Action |
|---|---|---|
| Tibialis posterior | Navicular tuberosity (primary insertion) | Plantarflexes the ankle and inverts the foot, supports the medial arch |
| Plantar calcaneonavicular (spring) ligament | Sustentaculum tali to navicular | Critical for supporting the talar head and the medial longitudinal arch |
| Tibialis anterior (partial) | Medial cuneiform and occasionally navicular | Dorsiflexes and inverts the foot |
| Dorsal talonavicular ligament | Talar neck to navicular dorsum | Stabilizes the talonavicular joint |
Joints and Articulations
| Joint | Type | Connects to |
|---|---|---|
| Talonavicular joint | Synovial ball-and-socket (part of transverse tarsal joint) | Talus |
| Naviculocuneiform joints | Synovial plane | Medial, intermediate, and lateral cuneiforms |
| Naviculocuboid joint (variable) | Fibrous or synovial | Cuboid (variable articulation) |
Common Pathologies
Navicular stress fracture
A common stress fracture in running and jumping athletes, occurring in the central one-third (watershed zone) with poor blood supply. Notoriously difficult to see on radiographs; MRI or CT is required.
Accessory navicular syndrome
Painful os tibiale externum (accessory bone at the navicular tuberosity) from mechanical irritation, tibialis posterior dysfunction, or fracture of the synchondrosis connecting it.
Kohler disease
Avascular necrosis of the navicular in children ages 3-7, causing midfoot pain and limping. Self-limiting condition that typically resolves completely.
Mueller-Weiss disease
Spontaneous osteonecrosis of the navicular in adults, causing progressive midfoot pain and arch collapse. More common in middle-aged women.
Clinical Relevance
Navicular stress fractures are frequently delayed in diagnosis because they are invisible on plain radiographs. Any athlete with vague dorsal midfoot pain and tenderness over the navicular (N spot) should undergo CT or MRI. Non-weight-bearing cast immobilization for 6-8 weeks is the standard treatment, with screw fixation for displaced or non-healing fractures. The accessory navicular is one of the most common accessory ossicles in the foot.
Development and Ossification
The navicular is the last tarsal bone to ossify, with its center appearing between ages 3 and 4 in girls and 4 and 5 in boys. This late ossification makes the navicular vulnerable to Kohler disease (AVN) during its period of rapid ossification and high mechanical stress.
Did You Know?
- Navicular comes from the Latin navicula meaning small boat, describing its concave proximal surface
- The navicular is the last tarsal bone to ossify, which is why Kohler disease occurs specifically in this bone
- An accessory navicular bone is present in about 10-14% of the population and is the most common accessory bone in the foot
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