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Muscle guide · Lower legs

Popliteus

Also called back of the knee muscle

The popliteus is a small, flat muscle deep behind the knee, forming the floor of the hollow at the back of the joint.

When you stand with the knee fully straight it locks with a slight twist. The popliteus untwists it, so the first moment of every step or squat from a straight knee starts here.

4 exercises4 with 3D demos3 sourcesUpdated 17 October 2026

Where the popliteus is and what it does

Shaded: the calves area. It marks the region, not the exact outline of the popliteus.
Starts at (origin)
The outer side of the thigh bone at the knee.Lateral femoral condyle, with some fibres from the fibular head
Attaches to (insertion)
The upper back of the shin bone.Posterior tibia above the soleal line
What it does
  • Unlocks a fully straight knee by rotating it, so it can bend.Unlocking of the extended knee (femoral external rotation on the planted tibia)
  • Helps bend the knee.Assists knee flexion
  • Draws the outer meniscus back as the knee bends, so it is not pinched.Retraction of the lateral meniscus
  • Steadies the back and outer corner of the knee.Posterolateral knee stabilisation
Nerve supply
Tibial nerve (given as L5, S1).

Sources 1, 2, 3

Exercises for the popliteus

No study has measured which exercises work it hardest. Knee-bending exercises use its action; it works alongside the hamstrings.

Machine leg curl demonstrated on the 3D figure3D demoMachine leg curlBeginner · Strength machineSeated Leg Curl demonstrated on the 3D figure3D demoSeated Leg CurlBeginner · Strength machineSlider hamstring curl demonstrated on the 3D figure3D demoSlider hamstring curlIntermediate · No equipmentNordic curl demonstrated on the 3D figure3D demoNordic curlAdvanced · An anchor point

Problems linked to the popliteus

Injuries to the back-outer corner of the knee

The popliteus is most often hurt as part of a posterolateral corner injury: a blow to the front-inner knee, a bow-legged force on a bent knee, overstraightening, or a dislocation. MRI is the scan of choice.

Source 1

Questions people ask

What does the popliteus do?

It unlocks a fully straightened knee by rotating it slightly so the knee can bend, helps bend it, and protects the outer meniscus.

Where is the popliteus?

Deep behind the knee, running from the outer side of the thigh bone to the upper back of the shin bone.

How is the popliteus injured?

Usually as part of an injury to the back-outer corner of the knee, from a blow, a twisting force on a bent knee, overstraightening or a dislocation.

Muscles it works with

Sources

  1. StatPearls · Anatomy, Bony Pelvis and Lower Limb: Popliteus Muscle (2023)
  2. StatPearls · Anatomy, Bony Pelvis and Lower Limb: Leg Posterior Compartment (2026)
  3. StatPearls · Anatomy, Bony Pelvis and Lower Limb: Tibial Nerve (2026)

Anatomy and movement education, not a diagnosis or treatment plan. If you have pain that follows an injury, is severe or getting worse, or comes with numbness, weakness or swelling, get it assessed. Health disclaimer.