First Metatarsal

What Constitutes the Primary Metatarsal

The first or primary metatarsal is the bone situated just behind the proximal phalanx of the big toe. It is the thickest, briefest, and most robust of the five metatarsals.

Structure and Points of Reference

Being a lengthy bone, it is divided into a head, body or shaft, and base. The head is the part on the side of the proximal phalanx, while the body is the middle part. The bone is somewhat flat, giving rise to two distinct surfaces, plantar and dorsal.

Connections

There are usually no joint surfaces on the sides of the base. The only joint facet in this area is on the lateral side, where an oval facet articulates with the second metatarsal. The bone is also in direct contact with the medial cuneiform bone through an articulation on the proximal side.

Distally, it connects with the first proximal phalanx (primary metatarsal-phalangeal joint). There are two distinct grooved facets for the two sesamoid bones to articulate and glide with movement.

Muscle Bond

• The plantar surface at the base has a rough oval tuberosity where the fibularis longus muscle’s tendon attaches.
• The tibialis anterior muscle also inserts to the base of the primary metatarsal
• The medial side of the bone is where the lateral portion of the first dorsal interosseus muscle originates from.

Sources

1. 1. Radiographic Anatomy of the Primary Metatarsal – Pubmed.ncbi.nlm.nih.gov
   2. Metatarsal Bones – Kenhub.com
   3. Metatarsals – Radiopaedia.org
   4. Anatomy of the Foot – Arthritis.org