Plantar calcaneonavicular ligament

At a glance

English

Plantar calcaneonavicular ligament

Latin (TA2)

Ligamentum calcaneonaviculare plantare

System

Ligament

Region

Foot

Side

Paired, left and right

About the plantar calcaneonavicular ligament

The plantar calcaneonavicular ligament is better known as the spring ligament. It spans the gap on the medial side of the sole between the calcaneus and the navicular, a gap that has no bone in it. Behind, it is fixed to the front edge of the sustentaculum tali, the shelf projecting from the inner side of the heel bone; in front, it reaches the underside and medial part of the navicular. Rather than a single strap, it is a complex of three parts: a superomedial band, a medioplantar oblique band and an inferior band, each ending on a slightly different area of the navicular.

The upper surface of the superomedial part carries a smooth pad of fibrocartilage covered by synovial membrane. The rounded head of the talus rests directly on this pad. The ligament therefore forms part of the socket of the talocalcaneonavicular joint, completing it between the facets on the calcaneus behind and the concave back of the navicular in front. Its medial edge merges with the front fibres of the ankle's deltoid ligament, and its underside is cradled by the tendon of tibialis posterior on its way to the navicular tuberosity.

By holding up the head of the talus, the spring ligament carries a large share of body weight in standing and walking and is a key passive support of the medial longitudinal arch. It works with the tibialis posterior tendon, which gives active support from below, and with the plantar aponeurosis.

When the ligament is stretched or torn, the head of the talus sinks downwards and medially, the arch falls and the forefoot drifts outwards: an acquired flatfoot that can make walking painful and tiring. This often follows failure of the tibialis posterior tendon, which leaves the ligament to bear the load on its own until it too gives way.

Attachments and function

Attaches from

The front edge of the sustentaculum tali, on the medial side of the calcaneus.

Attaches to

The plantar and medial aspects of the navicular, its three bands ending on slightly different areas.

Function

Holds up the talar head, forms part of the socket of the talocalcaneonavicular joint and helps maintain the medial longitudinal arch.

Nerve supply

Articular branches of the medial plantar nerve.

Blood supply

Branches of the medial plantar artery and the posterior tibial artery.