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Name of bone
The navicular bone is one of the tarsal bones found the foot. Its name derives from the bone's resemblance to a small boat, caused by the strongly concave proximal articular surface. The term navicular bone or hand navicular bone was formerly used for the scaphoid bone, one of the carpal bones of the wrist.
Located on the medial side of the foot, the navicular bone articulates proximally with the talus, distally with the three cuneiform bones, and occasionally laterally with the cuboid.
Figure 1. Medial view of the foot showing the navicular bone.
Figure 2. AP view of the navicular bone.
Muscle and ligament attachments
Figure 3. The posterior tibial tendon is seen attaching to the navicular in this medial view.
As the bones in the foot develop, a particular process is important for the navicular structure. In the early stage, the navicular bone is actually cartilaginous and has to progress and calcify in order to maintain a strong form.
In some cases, however, the three cuneiforms that compose the bone do not completely calcify as a unit, causing a protrusion along the medial arch, called the accessory navicular. Many people never have a problem with this extra bone.
Figure 4. AP view of an accessory navicular.
Others, though, develop a painful condition called accessory navicular syndrome. The accessory navicular has a tendency to put stress on two tendons and the ligament that run along its side. The tendon of the peroneus brevis muscle, which is the most distal of the two tendons; the tendon of the peroneus longus muscle, which extends to the posterior of the ankle; and the posterior talofibular ligament, which extends upward partway along the calf muscle, can be potentially affected by this protrusion. The wear and tear on the tendons can cause sharp pain with increased activity.
Accessory navicular syndrome can be corrected with surgery to file down or remove the protrusion and repair the tendons that were affected.