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Flexor Digitorum Longus Tendon (Knot of Henry)

tendo musculi flexoris digitorum longi (nodus Henrici)

The knot of Henry (master knot) is the crossing point of the flexor digitorum longus and flexor hallucis longus on the plantar midfoot, just plantar to the navicular. At this point the FDL passes dorsal to the FHL to gain its lateral position supplying the four lesser toes. The medial plantar nerve compression at this crossing produces jogger's foot. The lumbrical muscles of the foot arise from the FDL at the knot of Henry.

Region: Foot & Ankle

Biomechanics

Function & Actions

The knot of Henry represents the plantar FDL-FHL crossing where force is distributed to the four lesser toes; lumbrical origin point for toe extension

Clinical Relevance

Clinical Notes

The knot of Henry is the surgical landmark for: (1) FHL transfer to FDL for hallux rigidus (connecting FHL power to the lesser toes via the FDL), (2) medial plantar nerve decompression at the navicular, (3) accessing both long toe flexors for combined reconstruction. Its position beneath the navicular is marked by palpation of the navicular tuberosity on the medial plantar foot.

Pathology

Common Injuries & Conditions

Medial Plantar Nerve Entrapment at Henry Knot

Nerve compression at the FDL-FHL crossing point producing medial plantar foot burning in runners managed with targeted injection and decompression.