Navicular

Navicular is an anatomical term derived from the Latin naviculus, meaning a small boat. In medical usage the word has historically referred to several boat-shaped bones. The most common references are the navicular bone of the foot, the scaphoid bone of the wrist (historically called the navicular bone), and the navicular bone of the horse’s hoof.

The navicular bone of the foot, or navicular tarsal bone, is located on the medial side of the midfoot. It lies between the head of the talus superiorly and the three cuneiform bones distally, forming part of the medial longitudinal arch. The bone is boat-shaped and features a plantarly directed navicular tuberosity that serves as an attachment site for the tibialis posterior tendon. It can be involved in stress injuries and fractures, particularly in runners and other athletes.

In the wrist, navicular is an older term for the scaphoid bone, a carpal bone in the proximal row. The scaphoid lies near the radius and articulates with the lunate medially and with the distal row carpal bones, including the trapezium and capitate. It is also boat-shaped and is a common site of fracture after a fall on an outstretched hand. Because its blood supply flows retrograde from distal vessels, scaphoid fractures carry a risk of avascular necrosis and delayed healing if not treated promptly.

In equine anatomy, the navicular bone is the small distal sesamoid bone located behind the coffin joint within the deep digital flexor tendon. It articulates with the coffin bone and is associated with a navicular bursa. Navicular disease refers to degenerative or inflammatory conditions affecting this region and is a common cause of chronic forelimb lameness in horses.