Lumbricals of the foot

Deep muscle — it lies under other muscles. X-ray makes the muscles over it see-through.

Origin

Tendons of the flexor digitorum longus

Insertion

Inner sides of the extensor expansions of toes 2 to 5

Action

Flex the small toes at their base joints and extend them at the middle and end joints

Nerve supply

Medial plantar nerve (first lumbrical, S1–S3) and lateral plantar nerve (second to fourth, S2–S3)

Four small worm-like muscles in the sole, numbered from the big-toe side. They keep the small toes straight while the base joints bend, which helps the toes press flat against the ground.