Disc herniation between L4 and L5 involves nerve root?

**Core Concept**
Disc herniation between L4 and L5 involves compression of the L5 nerve root, due to its anatomical relationship with the intervertebral disc. The L5 nerve root emerges from the spinal canal between the L4 and L5 vertebrae, making it vulnerable to compression by a herniated disc in this region.

**Why the Correct Answer is Right**
The L5 nerve root is responsible for controlling the muscles of the lower leg, including the tibialis anterior, peroneus longus, and extensor digitorum longus. Compression of the L5 nerve root can lead to symptoms such as pain, weakness, and numbness in the lower leg and foot. The L5 nerve root also provides sensory innervation to the lateral aspect of the foot, which is often affected in cases of L5 nerve root compression. The L4 nerve root, on the other hand, is responsible for controlling the muscles of the thigh, including the quadriceps and iliopsoas.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the L4 nerve root is not typically affected by a disc herniation between L4 and L5.
**Option B:** This option is not provided.
**Option C:** This option is incorrect because the S1 nerve root is not typically affected by a disc herniation between L4 and L5.
**Option D:** This option is not provided.

**Clinical Pearl / High-Yield Fact**
When examining a patient with a suspected disc herniation, it's essential to perform a thorough neurologic examination, including testing of the L5 nerve root with the straight leg raise test (SLR). A positive SLR test can indicate L5 nerve root compression and guide further diagnostic testing.

**Correct Answer:** C.