Popliteus muscle

Popliteus muscle
Muscles of the back of the leg. Deep layer. (Popliteus visible at center top.)
Latin	musculus popliteus
Gray's	subject #129 484
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

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].

Trigger points

A popliteus shortened by trigger points can cause pain near its tendinous origin at the lateral knee.

Additional images

• 

  Right femur. Posterior surface.

• 

  Bones of the right leg. Posterior surface.

• 

  Capsule of right knee-joint (distended). Posterior aspect.

• 

  The popliteal, posterior tibial, and peroneal arteries.

See Also

• Posterolateral Knee

References

1. ^ Gray, Henry. 1918. Anatomy of the Human Body. Page 485

External links

• LUC pop
• 93978702 at GPnotebook
• SUNY Labs 15:st-0413
• popliteus+%28muscle%29 at eMedicine Dictionary
• PTCentral

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.