A 50-year-old woman who is a known diabetic and hypeensive has developed vesicular eruption on the trunk in T6 dermatome. Dermatologist confirmed it as Herpes Zoster. She is complaining severe pain and increased sensitivity to touch. Which of the following receptors sense sustained pressure?
**Core Concept**
The question is testing the understanding of the sensory innervation of the skin and the specific receptors involved in sensing different types of stimuli, including sustained pressure. The dermatome distribution and the clinical presentation of Herpes Zoster suggest involvement of the trigeminal nerve (cranial nerve V) or the thoracic nerves (T1-T12), which are part of the peripheral nervous system.
**Why the Correct Answer is Right**
Herpes Zoster, also known as shingles, is caused by reactivation of the varicella-zoster virus, which infects the dorsal root ganglia of the spinal nerves. The virus can cause damage to the nerve fibers, leading to pain and sensory disturbances. The patient's complaint of severe pain and increased sensitivity to touch suggests involvement of the nociceptors, which are responsible for detecting painful stimuli. However, the question specifically asks about receptors that sense sustained pressure. The correct answer is Merkel cell-neurite complexes, which are slowly adapting type I mechanoreceptors that respond to sustained pressure and light touch. These receptors are found in the epidermis and are responsible for detecting subtle changes in texture and shape.
**Why Each Wrong Option is Incorrect**
* **Option A:** Ruffini corpuscles are slowly adapting type II mechanoreceptors that respond to skin stretch and skin stretch velocity. They are not primarily responsible for sensing sustained pressure.
* **Option B:** Pacinian corpuscles are rapidly adapting mechanoreceptors that respond to vibration and pressure changes. They are not responsible for sensing sustained pressure.
* **Option C:** Meissner's corpuscles are rapidly adapting mechanoreceptors that respond to light touch and low-frequency vibration. They are not responsible for sensing sustained pressure.
**Clinical Pearl / High-Yield Fact**
Merkel cell-neurite complexes are responsible for detecting subtle changes in texture and shape, which is essential for tactile perception. Damage to these receptors, as seen in neuropathic pain conditions, can lead to altered sensation and loss of tactile acuity.
**Correct Answer:** C. Merkel cell-neurite complexes.