Anterior horn cells are affected in –
**Core Concept**
Anterior horn cells are a type of motor neuron located in the ventral horn of the spinal cord. They play a crucial role in transmitting signals from the central nervous system to skeletal muscles, facilitating voluntary movements.
**Why the Correct Answer is Right**
The anterior horn cells are responsible for transmitting motor signals, but they can be affected by various conditions, including poliomyelitis (polio). In polio, the poliovirus infects and destroys the anterior horn cells, leading to muscle weakness, paralysis, and atrophy. This is because the poliovirus targets the motor neurons, disrupting the normal functioning of the anterior horn cells.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because anterior horn cells are not directly affected in Guillain-Barré syndrome, which is an autoimmune disorder that primarily affects the peripheral nerves.
* **Option B:** This option is incorrect because amyotrophic lateral sclerosis (ALS) affects both upper and lower motor neurons, but the primary involvement is of the corticospinal tracts and the motor neurons in the cerebral cortex and the brainstem, not the anterior horn cells exclusively.
* **Option C:** This option is incorrect because peripheral neuropathy affects the peripheral nerves, including the nerve roots and the peripheral nerve trunks, but not the anterior horn cells specifically.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that polio can lead to a range of symptoms, from mild to severe, including muscle weakness, paralysis, and atrophy. The anterior horn cells are particularly vulnerable to the effects of the poliovirus, making this a critical concept for medical students to grasp.
**Correct Answer:** D. Poliomyelitis