L1: mechanoreceptors

What aspect of flavor do oral mechanoreceptors detect?

• food texture

• consistency

• physical feel

Where are the cell bodies of primary orofacial somatosensory neurons located?

trigeminal ganglion

• Most are pseudounipolar neurons with bifurcated axons.

What are the 4 morphologically distinct cutaneous mechanoreceptors?

• Merkel discs

• Meissner corpuscles

• Ruffini endings

• Pacinian corpuscles

Which mechanoreceptor detects sustained pressure, indentation, and edges?

Merkel disc (SA I) — slowly adapting, small receptive field, superficially located

Which mechanoreceptor detects light touch and tapping?

Meissner corpuscle (RA I) — rapidly adapting, small receptive field, superficially located

Which mechanoreceptor detects skin stretch?

Ruffini ending (SA II) — slowly adapting, large receptive field, located deep in the dermis.

Which mechanoreceptor detects vibration and deep pressure?

Pacinian corpuscle (RA II) — rapidly adapting, large receptive field, located deep in the dermis, with an onion-like capsule.

How do slowly adapting (SA) and rapidly adapting (RA) mechanoreceptors differ?

• SA: Continue firing during sustained stimulation

• RA: Fire mainly when stimulation begins or ends

How does receptive field size affect tactile sensitivity?

Smaller receptive fields allow more precise stimulus localization and greater tactile acuity.

What does a smaller two-point discrimination threshold indicate?

Greater tactile sensitivity, generally associated with smaller receptive fields.

Which body regions have the highest mechanoreceptor density?

• Fingertips

• Perioral region (lips)

• Tongue

Which is more sensitive to touch: the tip or posterior region of the tongue?

tongue tip, because it has smaller receptive fields and lower two-point discrimination thresholds

Which cranial nerve carries most somatosensory information from the orofacial region?

Trigeminal nerve (CN V)

• V1: Ophthalmic

• V2: Maxillary

• V3: Mandibular

What sensory nerve endings are found in oral mucosa?

• Free nerve endings

• Merkel discs

• Meissner corpuscles

What is microneurography used for?

Recording electrical activity from individual peripheral sensory nerve fibers to characterize their responses to mechanical stimulation

What is the purpose of von Frey filaments?

To measure mechanical detection thresholds by applying controlled forces

What is the predominant periodontal mechanoreceptor, and what are its functions?

Ruffini endings — provide sensory feedback during chewing and help protect teeth from excessive bite forces

Are periodontal Ruffini endings slowly or rapidly adapting?

Slowly adapting (SA) — they continue firing during sustained tooth displacement

What does it mean that periodontal mechanoreceptors are directionally sensitive?

their firing response depends on the direction of force applied to a tooth.

In periodontal mechanoreceptor recordings, what does vector length indicate?

The magnitude of the neural response to force in that direction. Longer vectors indicate greater sensitivity.

What is a receptor-bearing tooth?

The tooth whose stimulation produces the strongest response in a particular periodontal afferent fiber

How does directional sensitivity differ between anterior teeth and molars?

• Anterior teeth: Respond to forces from multiple directions.

• Molars: Greater sensitivity to occlusal loading associated with grinding.

How do periodontal mechanoreceptors respond to increasing bite force?

Firing increases most strongly at low forces (especially below ~1–1.5 N) and tends to plateau at higher forces