Note the big toe has no middle phalanx.

The flexor hallucis longus and flexor digitorum longus flex the interphalangeal joint of the big toe and lateral four toes, respectively.

The tendons of both of these muscles cross as they reach their distal attachments.

The amount of flexion is very considerable, but extension is limited by the plantar and collateral ligaments.

This article incorporates text in the public domain from page 359 of the 20th edition of Gray's Anatomy (1918)