Posterior thigh dermatome is:
**Core Concept**
The dermatomes are areas of skin supplied by nerves that arise from specific spinal nerve roots. The posterior thigh is innervated by the nerves that arise from the lumbar and sacral spinal cord segments. This question tests the student's knowledge of dermatomal distribution.
**Why the Correct Answer is Right**
The posterior thigh dermatome is supplied by the L2-L4 nerve roots. These nerve roots arise from the lumbar spinal cord and innervate the posterior aspect of the thigh. The L2-L4 nerve roots give rise to the femoral nerve, which provides motor innervation to the muscles of the thigh and sensory innervation to the skin of the anterior thigh. The posterior thigh, however, is innervated by the nerves that arise from the lumbar spinal cord, specifically the L2-L4 nerve roots.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the correct dermatome for the posterior thigh.
**Option B:** This option is incorrect because it is not the correct dermatome for the posterior thigh.
**Option D:** This option is incorrect because it is not the correct dermatome for the posterior thigh.
**Clinical Pearl / High-Yield Fact**
The dermatomes can be remembered using the following mnemonic: "L2-L4 for the back of the thigh, L5-S2 for the front." This mnemonic helps students recall the correct dermatomes for the posterior and anterior thighs.
**Correct Answer: C. L2-L4**