At the L4 level, which muscle groups are 3/5?

At the L4 level, which muscle groups are 3/5?

• A. Medial knee flexors and ankle dorsiflexors
• B. Hip flexors and abdominals
• C. Paraspinals and hip extensors
• D. Long toe extensors and plantar flexors

Answer: (A)

At this level, the motor function being tested is what muscles receive innervation from that spinal level and how a 3/5 grade reads. A 3/5 means the person can move the joint against gravity but cannot resist external force. For the L4 level, the ankle dorsiflexors (primarily the tibialis anterior) are a classic L4-innervated group; weakness here often shows up as a reduced but present ability to lift the foot against gravity. The medial knee flexors (such as the muscles around the inner thigh like gracilis/sartorius) can also reflect L4 involvement in some regional testing patterns, producing movement that is present but not strong. The other options involve muscles more strongly associated with other spinal levels. Hip flexors and abdominals are mainly driven by higher levels (hip flexors around L2–L3; abdominals higher thoracic/lumbar). Paraspinals and hip extensors span multiple levels and often rely on lower or upper segments beyond L4. Long toe extensors and plantar flexors are tied to L5-S1 contributions and S1, so their function would be weaker or absent at a pure L4 level. So, at the L4 level, a 3/5 finding would most align with ankle dorsiflexion and, in some testing schemes, medial knee flexion, fitting the option described.

At this level, the motor function being tested is what muscles receive innervation from that spinal level and how a 3/5 grade reads. A 3/5 means the person can move the joint against gravity but cannot resist external force. For the L4 level, the ankle dorsiflexors (primarily the tibialis anterior) are a classic L4-innervated group; weakness here often shows up as a reduced but present ability to lift the foot against gravity. The medial knee flexors (such as the muscles around the inner thigh like gracilis/sartorius) can also reflect L4 involvement in some regional testing patterns, producing movement that is present but not strong.

The other options involve muscles more strongly associated with other spinal levels. Hip flexors and abdominals are mainly driven by higher levels (hip flexors around L2–L3; abdominals higher thoracic/lumbar). Paraspinals and hip extensors span multiple levels and often rely on lower or upper segments beyond L4. Long toe extensors and plantar flexors are tied to L5-S1 contributions and S1, so their function would be weaker or absent at a pure L4 level.

So, at the L4 level, a 3/5 finding would most align with ankle dorsiflexion and, in some testing schemes, medial knee flexion, fitting the option described.