Popliteus muscle

Popliteus muscle
Popliteus muscle
	Muscles of the back of the leg. Deep layer. (Popliteus visible at center top.)
Details
Origin	posterior-medial tibia under the tibial condyles
Insertion	middle facet of the lateral surface of the lateral femoral condyle
Artery	popliteal artery
Nerve	tibial nerve
Actions	Lateral rotation of femur and flexion of knee
Identifiers
Latin	musculus popliteus
TA98	A04.7.02.050
TA2	2665
FMA	22590
	Anatomical terms of muscle [edit on Wikidata]

The popliteus muscle in the leg is used to unlock the knee during walking/running by laterally rotating the femur on the tibia (or medially rotating the tibia) during a closed chain movement (such as one with the foot in contact with the ground).

Origin and insertion

It originates from lateral surface of lateral condyle of femur, origin is intracapsular outer margin of lateral meniscus of knee joint. Insertion-posterior surface of shaft of tibia above soleal line.

Innervation

Nerve supply is via the tibial nerve from spinal roots L5 and S1.

Action

The Popliteus assists in flexing the leg upon the thigh; when the leg is flexed, it will rotate the tibia inward.

It is especially called into action at the beginning of the act of bending the knee, in as much as it produces the slight inward rotation of the tibia, which is essential in the early stage of this movement.

When the knee is in full extension; the femur slightly medially rotates on the tibia to lock the knee joint in place. Popliteus is often referred to as the "Key" to unlocking the knee since it begins knee flexion by laterally rotating the femur on the tibia.

Popliteus is also attached to the lateral meniscus in the knee; and draws it posteriorly during knee flexion to prevent crushing the meniscus between the tibia/femur as the knee flexes.

Variations

Additional head from the sesamoid bone in the outer head of the Gastrocnemius.

Popliteus minor, rare, origin from femur on the inner side of the Plantaris, insertion into the posterior ligament of the knee-joint.

Peroneotibialis, 14% of population. Origin is inner side of the head of the fibula, insertion into the upper end of the oblique line of the tibia, it lies beneath the Popliteus^[1].