The first metatarsal head Surface Anatomy

Location

The head of the first metatarsal comprises the proximal potion of the first metatarsophalangeal joint which may be recognized as the convex contour on the medial aspect of the foot at the base of the great toe. With passive extension of the great toe, a skin crease develops over the top of the first metatarsophalangeal joint. The extensor hallucis longus tracks over top the first metatarsal head. The skin on the plantar aspect of the foot underlying the head of the first metatarsal should be callused due to weight bearing.

Significance

Hallux valgus describes a lateral deviation of the great toe resulting in a more pronounced medial contour created by the underlying head of the first metatarsal.

Tenderness over the head of the first metatarsal is most often due to bunion formation. This condition often coincides with hallux valgus and is the result of bone deposition at the head of the first metatarsal and swelling of the overlying soft tissue.

Osteophytes may also be observed at the head of the first metatarsal as nodular deformities in patients with osteoporosis.

Hallux varus is due to medial deviation of the great toe. Most often seen as a complication of corrective surgery for hallux valgus.