Flexores digitorum [digitalis] profundi muscles

The deep digital flexor muscle (Musculi flexores digitorum [digitalis] profundi) consists of three separate heads:

• The lateral digital flexor muscle (formerly flexor hallucis longus)
• The medial digital flexor muscle (formerly flexor digitorum longus)
• The caudal tibial muscle (except in carnivores, where the tendon of this muscle has an independent termination on the medial surface of the tarsus and does not contribute to the formation of the (common) deep digital flexor tendon.

These three heads lie on the caudal surface of the tibia and fibula from which they take origin. They unite distally to form a strong tendon, the common tendon (tendo communis in the NAV) of deep digital flexor muscle, either at the middle of the crus or distal to the tarsus in different species. The tendon continues distally on the plantar aspect of the metatarsus and inserts with a branch for each functional digit on the flexor surface of the distal phalanges, thus resulting in four tendons of insertion in carnivores and pigs, tow in ruminants and one in the horse. The individual branches are surrounded by synovial sheats at the level of the tarsus.