Question

What is the action of the biceps femoris?

Answer 1

The biceps femoris is a key muscle in the posterior thigh compartment, responsible for flexing the knee, extending the hip, and also participates in the abduction and lateral rotation of the thigh.

Step-by-step explanation:

Action of the Biceps Femoris

The biceps femoris is a key muscle within the posterior compartment of the thigh, which is a part of what is commonly known as the hamstrings. It plays a crucial role in the movement of both the hip and the knee joints. The action of the biceps femoris is to flex the leg at the knee and to also assist in hip extension. Additionally, this versatile muscle is involved in abducting (moving away from the midline of the body) and laterally rotating the thigh at the hip joint, which allows for movements such as sitting cross-legged.

When the knee bends, the biceps femoris is the agonist, meaning it is the primary muscle causing the movement. In contrast, when extending the leg at the knee, such as when kicking, the quadriceps femoris acts as the antagonist to the biceps femoris, opposing its action. Thus, the biceps femoris and quadriceps femoris dynamically oppose each other during different movements of the knee.

Answer 2

The main action of biceps femoris is the knee flexion and hip extension.

Step-by-step explanation:

Biceps femoris muscle is a thigh muscle present in the posterior part of the body. This muscle has two heads of origin.

Biceps femoris is involved in the knee flexion. The kknee flexion decreses the angle between the femur and tibia. Biceps femoris is also involved in the hip extension. The hip joints are open during hip extension.