Knee extensors known as the quadriceps femoris consist of the
(a) Three vastus muscles and the rectus femoris
(b) Biceps femoris, gracilis, and sartorius
(c) Popliteus, iliopsoas, and gracilis
(d) Gastrocnemius, tibialis, and peroneus

Verified step by step guidance

1. Step 1: Understand the function of knee extensors. Knee extensors are muscles responsible for straightening the knee joint, increasing the angle between the thigh and the lower leg.
2. Step 2: Recall the main muscles that make up the quadriceps femoris group. This group is primarily responsible for knee extension.
3. Step 3: Identify the muscles in the quadriceps femoris group. These include three vastus muscles (vastus lateralis, vastus medialis, vastus intermedius) and the rectus femoris.
4. Step 4: Compare the options given with the known quadriceps muscles. Option (a) lists the three vastus muscles and the rectus femoris, which matches the quadriceps femoris group.
5. Step 5: Recognize that the other options list muscles involved in different functions such as knee flexion or hip movement, so they are not correct for knee extensors.

Key Concepts

Anatomy of the Quadriceps Femoris

The quadriceps femoris is a group of four muscles located at the front of the thigh responsible for knee extension. It includes three vastus muscles—vastus lateralis, vastus medialis, and vastus intermedius—and the rectus femoris. Understanding these muscles is essential to identify the correct components of the knee extensors.

Function of Knee Extensors

Knee extensors are muscles that straighten the knee joint by contracting and pulling the lower leg forward. The quadriceps femoris is the primary muscle group performing this action, playing a crucial role in movements like walking, running, and jumping.

Distinguishing Muscle Groups of the Thigh and Leg

Different muscle groups in the thigh and leg have distinct functions and locations. For example, the biceps femoris is a knee flexor and part of the hamstrings, while muscles like the gastrocnemius are involved in ankle movement. Recognizing these differences helps avoid confusion when identifying knee extensors.