Question

The muscle responsible for unlocking the knee joint is:
(A) Popliteus muscle
(B) Soleus
(C) Soleus and gastrocnemius
(D) Plantaris
Choose the most appropriate answer from the options given below:

• (A) only
• (A) and (B) only
• (B) and (C) only
• (C) only

Hint:

Remember — Popliteus unlocks the knee; think ‘P for Popliteus, P for Pivot’.

Answer 1

The Correct Option is A

The popliteus muscle is a small muscle located at the back of the knee joint.
Its primary function is to ‘unlock’ the knee from the fully extended position by laterally rotating the femur on the tibia when the foot is on the ground.
This action initiates knee flexion after full extension.
The soleus, gastrocnemius, and plantaris are calf muscles primarily responsible for plantar flexion at the ankle, not directly for unlocking the knee.
Therefore, only the popliteus muscle performs this unlocking function.