Flexor Digitorum Longus (FDL)

Authors

Affiliations

Nathaniel Yomogida, B.S., SPT

Doctor of Physical Therapy

B.S. in Kinesiology

Chloë Kerstein, B.S., SPT

Doctor of Physical Therapy

B.A. in Neuroscience

Schematic of Deep Flexors of the Posterior Compartment of the Leg
1: Tibialis Posterior
2: FDL
3: FHL
4: Popliteus¹

Deep Flexors of the Posterior Compartment of the Leg¹

Muscle	Origin	Insertion	Innervation	Action
Flexor digitorum longus	Middle 1/3 of posterior surface of Tibia	Bases of 2-5 Distal Phalanges	Tibial n. L5 - S2	TCJ: PF STJ: Inversion 2nd-5th Toe: MTP Flexion, PIP Flexion, DIP Flexion

Origin

Tibia (middle third of posterior surface)¹

Insertion

Bases of 2-5 distal phalanges¹

Innervation

Tibial N. (L5, S1, S2)¹

Action

• TCJ: PF¹
• STJ: INV¹
• MTP & IP 2-5: Flexion¹

MMT

“The FDL and brevis muscles produce IP joint flexion. The motion is tested with the foot in the anatomic position. If the gastrocnemius muscle is shortened, preventing the ankle from assuming the anatomic position, the knee is flexed. The toes may be tested simultaneously. The foot is held in the midposition, and the metatarsals are stabilized. Resistance is applied beneath the distal and proximal phalanges”²

Pails & Rails

Read more about [P.A.I.L.’s and R.A.I.L.’s here]

P.A.I.L.’s

• Plantarflexion
• Inversion
• 2-5 MTP/IP Flexion

R.A.I.L.’s

• Dorsiflexion
• Eversion
• 2-5 MTP/IP Extension

Stretch

• 3D Calf Stretch

References

1.

Gilroy AM, MacPherson BR, Wikenheiser JC, Voll MM, Wesker K, Schünke M, eds. Atlas of Anatomy. 4th ed. Thieme; 2020.

2.

Dutton M. Dutton’s Orthopaedic Examination, Evaluation, and Intervention. 5th ed. McGraw Hill Education; 2020.