The opponens digiti minimi of the foot opposes the fifth metatarsal to help cup the lateral foot, analogous in name to its hand counterpart but much less developed given the limited opposition function of the little toe. It runs along the lateral foot border between the cuboid and fifth metatarsal, and its contraction marginally cups the lateral foot to grip uneven terrain.
| Origin | Plantar surface of the cuboid and the long plantar ligament |
|---|---|
| Insertion | Lateral border of the fifth metatarsal shaft |
| Nerve Supply | Lateral plantar nerve (S1, S2) |
| Blood Supply | Lateral plantar artery |
| Actions | Abducts and flexes the fifth metatarsal; Assists in cupping the lateral foot |
|---|
While true opposition of the little toe is not functionally significant in humans (unlike the hand), the opponens digiti minimi contributes to the stability and cupping of the lateral plantar surface during terrain adaptation and single-leg balance activities.
The opponens digiti minimi of the foot is rarely assessed individually in clinical practice but may be tested as part of comprehensive lateral plantar nerve assessment in tarsal tunnel syndrome. Fifth metatarsal base fractures at the styloid (Jones fracture zone) can disrupt the attachments of the plantar intrinsic muscles including the opponens at the cuboid-fifth metatarsal junction.
Not individually palpable but assessed as part of lateral foot intrinsic muscle function.
Compression of the nerve supplying the opponens digiti minimi and adjacent muscles in tarsal tunnel syndrome producing lateral plantar numbness and intrinsic weakness.
