Flexor Digitorum Brevis
Foot
Equivalent of flexor digitorum superficialis in the hand — its tendons split to let the long flexor pass through.
Function
Flexes PIP joints of toes 2-5, supports longitudinal arch
Origin
Medial calcaneal tuberosity, plantar aponeurosis
Insertion
Middle phalanges of digits 2-5 (splits to let FDL pass through)
Innervation
Medial plantar nerve (S1-S3)