Nerve ending sensitive to noxious stimuli are present in all except
**Core Concept**
Free nerve endings are specialized sensory receptors found in the skin and other tissues that are responsible for detecting and transmitting pain signals to the central nervous system in response to noxious stimuli. These endings contain nociceptors, specialized nerve endings that are sensitive to painful or damaging stimuli such as heat, cold, mechanical pressure, or chemical irritants.
**Why the Correct Answer is Right**
Nociceptors release the neurotransmitter substance P, which binds to specific receptors on the surface of spinal cord neurons, initiating the transmission of pain signals. The activation of nociceptors triggers a complex signaling pathway that involves the activation of ion channels, the release of neurotransmitters, and the transmission of pain signals to the brain. This process is essential for the detection and perception of pain.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because free nerve endings are indeed found in the skin, where they play a crucial role in detecting and transmitting pain signals.
**Option B:** This option is incorrect because free nerve endings are also found in other tissues, such as muscles, joints, and internal organs, where they detect and respond to noxious stimuli.
**Option C:** This option is incorrect because free nerve endings are not typically found in the teeth, where pain is detected by specialized nociceptors known as pulpal nociceptors.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the perception of pain is a complex process that involves the activation of nociceptors, the transmission of pain signals to the brain, and the interpretation of those signals. Understanding the anatomy and physiology of pain perception is crucial for the diagnosis and management of pain disorders.
**Correct Answer:** C.