Lower limb

Quadratus Plantae

Musculus quadratus plantae

Origin

Medial and lateral heads on the plantar surface of the calcaneus, and the long plantar ligament

Insertion

Lateral border of the tendons of flexor digitorum longus, which continue to the distal phalanges of toes 2-5

Function

Corrects the oblique pull of the flexor digitorum longus tendons into a straight line and reinforces flexion of toes 2-5

Innervation

Lateral plantar nerve (the only foot muscle innervated directly by this nerve without the intervention of a long leg muscle)

Movement & chain

Realigns the oblique pull of the flexor digitorum longus into a straight longitudinal traction line for toes II–V.

Palpation

Deep in the posterior sole under the flexor digitorum brevis; cannot be directly palpated through the thick heel pad.

Clinical

Corrects the oblique angle of pull of the flexor digitorum longus tendon into a straight axis; involved in deep plantar heel pain syndromes.

Segmental innervation

S1-S2 (lateral plantar nerve).

In clinical practice

Skin and pressure point inspection; maintain comfortable positioning and proper body mechanics during patient handling and daily care.

Region in the model

Lower limb