Which of the following quadriceps femoris muscles help in flexion of the thigh?

AIIMS Patna NO - 2020

Applied Anatomy

Hard

Appeared in: AIIMS Patna NO - 2020

Explanation

The rectus femoris is the only muscle in the quadriceps group that crosses two joints: the hip and the knee.
It originates from the anterior inferior iliac spine of the ilium (a part of the hip bone).
This anatomical position allows it to act as a flexor of the thigh at the hip joint, in addition to its primary role as an extensor of the knee.
Activities like kicking a ball or lifting the knee high involve the action of the rectus femoris.

Option B: The vastus medialis originates from the femur and inserts into the patella. It does not cross the hip joint, so it cannot contribute to thigh flexion.
Option C: The vastus intermedius is located deep to the rectus femoris. It originates from the shaft of the femur and does not cross the hip joint, thus it cannot flex the thigh.
Option D: The vastus lateralis originates from the femur and, like the other vasti muscles, does not cross the hip joint. Therefore, it cannot participate in thigh flexion.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Anatomy and function of the quadriceps femoris muscles as background academic context rather than a clinical decision trigger.
A strain or tear of the rectus femoris can cause pain with both hip flexion and knee extension, complicating diagnosis and recovery. It is a common injury in sports involving kicking or sprinting.
Nurses may need to assess the quadriceps for strength and function post-surgery (e.g., knee replacement) or after an injury. Testing both knee extension and hip flexion helps isolate which part of the muscle group may be affected.
What if a patient reports pain at the front of the hip when lifting their leg, but has no pain when straightening their knee against resistance? This pattern strongly suggests an injury to the hip flexors, specifically the rectus femoris or iliopsoas, rather than the vasti muscles.

How to Approach the Question

First, identify the core of the question, which is asking about the function (flexion of the thigh) of a specific muscle group (quadriceps femoris).
Recall the fundamental principle of muscle action: a muscle must cross a joint to produce movement at that joint.
Visualize or recall the anatomy of the quadriceps muscles. Remember that this group has four parts.
Differentiate the origin points of the four muscles. The rectus femoris originates from the hip bone (pelvis), while the three vasti muscles (medialis, lateralis, intermedius) originate from the thigh bone (femur).
Conclude that since only the rectus femoris crosses the hip joint, it is the only one capable of flexing the thigh.
Select the option that names the rectus femoris.

Concept Tested & Keywords

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E6 Anatomy BDChaurasia V2 10e Part 1 p. 75-77

E6 Osteology InderbirSingh 5e pp. 179-181, 181-183