Comprehensive Osteopathic Medical Licensing Examination (COMLEX USA) Practice

What muscle is associated with the L5 motor nerve root during examination?

1. Quadriceps

2. Extensor hallucis longus

3. Psoas

4. Gastrocnemius

The correct answer is: Extensor hallucis longus

The muscle associated with the L5 motor nerve root is the extensor hallucis longus. This muscle is primarily responsible for the extension of the big toe and contributes to the dorsiflexion of the foot. During a clinical examination, testing the strength of the extensor hallucis longus can help evaluate the function of the L5 nerve root. L5 is part of the lumbosacral plexus, and its innervation is crucial for the proper functioning of certain muscle groups in the lower extremity. When assessing the L5 nerve root, clinicians often observe movements and strength tests specifically target these muscles. Effective dorsiflexion, including the ability to extend the big toe, is essential in many activities, and weakness could indicate an injury or compromise in the L5 nerve root. The other muscles mentioned are innervated by different nerve root levels. The quadriceps muscle is primarily associated with the L3 and L4 nerve roots. The psoas muscle, which is involved in hip flexion, is associated with L1 and L2. The gastrocnemius muscle is primarily innervated by the S1 and S2 nerve roots, as it plays a role in plantar flexion. Thus, these muscles