Mechanoreceptors are specialized sensory neurons that detect mechanical stimuli including touch, pressure, vibration, and stretch. They are essential for somatosensory perception and proprioception.
- Meissner's corpuscles: Light touch, low-frequency vibration (30-50 Hz)
- Pacinian corpuscles: Deep pressure, high-frequency vibration (250-300 Hz)
- Merkel's discs: Sustained pressure, texture perception
- Ruffini endings: Skin stretch, finger position
- Detect crude touch and pressure
- Also function as nociceptors and thermoreceptors
- Piezo1/2: Primary mechanosensors, widely expressed
- TREK/TRAAK channels: Potassium leak channels
- ASICs: Acid-sensing ion channels
- Nav1.1, Nav1.6, Nav1.7: Voltage-gated sodium channels
- STOML3: Regulates mechanosensitivity
- VLRT1/2/3: Vestigial-like proteins
- CDC42: Cytoskeletal regulation
- Mechanical stimulus deforms membrane
- Mechanosensitive channels open
- Na+ and Ca2+ influx causes depolarization
- Action potentials generated at first node of Ranvier
- Signals transmitted via dorsal columns to brain
- Fine touch, vibration, proprioception
- First-order neurons in dorsal root ganglion
- Synapse in dorsal column nuclei (cuneate/gracile)
- Cross in medulla, ascend to VPL thalamus
- Primary somatosensory cortex
- Crude touch, pressure
- Second-order neurons cross in spinal cord
- Relay in thalamus to somatosensory cortex
- Reduced tactile discrimination
- Impaired vibration sense
- Contributes to sensory symptoms
- Tactile perception deficits
- Impaired two-point discrimination
- Related to cortical degeneration
- Common peripheral neuropathy type
- Loss of vibration sense and touch
- Increases risk of foot ulcers
- Prominent mechanoreceptor loss
- Sensory ataxia from proprioceptive deficit
- Demyelination affects mechanoreceptor pathways
- Vibration and position sense impaired
- Detect muscle length changes
- Located within intrafusal fibers
- Ia afferents: velocity sensing
- II afferens: static position
- Detect muscle tension
- Ib afferents: prevent muscle damage
- Contribute to stretch reflex
- Ruffini endings in joint capsules
- Monitor joint angle and position
- Monofilament test: Touch perception
- Vibration testing: 128 Hz tuning fork
- Proprioception testing: Joint position sense
- Quantitative sensory testing (QST)
- Protective footwear for sensation loss
- Regular screening for ulcers
- TRPV4 antagonists under development
- Piezo channel blockers in trials