NEUR 2026: Touch

Afferent neurons are

psuedounipolar

What is the innermost layer of connective tissue that supports individual nerve fibers?

the endoneurium

What is endoneurial fluid?

extracellular fluid within the endoneurium

Mechanical stimulation opens what channels?

Piezo2 channels, which causes depolarization

SA1 is a type of what?

A-beta fiber

Heavily mylineated A-alpha fibers innervate on…

the muscle spindle and terminal in the central and ventral spinal cord

Heavily myelinated A-beta fibers innervate on…

a Merkel cell or hair follicle and terminate in laminae III, IV, and V

Lightly myelinated A-delta fibers are…

temperature-sensing neurons that terminate in laminae I and V

Unmyelinated C fibers are…

nociceptive neurons that terminate in laminae I and II

Free nerve endings

sense pain, temperature, and crude touch / connect to A-delta + C fibers

Meissner corpuscle

detect light touch + texture / connect to A-beta fibers

Merkel cell-neurite complex

sense steady pressure and texture / connect to A-beta fibers

Ruffini corpuscle

detect skin stretch + joint movement / connect to A-beta fibers

Pacinian corpuscles

sense vibration and deep pressure / connect to A-beta fibers

Guard hairs

protect skin and enhance touch sensation

Zigzag hairs

sensitive to movement / aid in tactile perception

Awl hairs

provide texture information and enhance touch sensitivity

Touch dome

structured associated w/ Merkel cells

What is the primary somatosensory cortex in charge of?

touch, proprioception, pain, temperature, and precise spatial localization

What is the secondary somatosensory cortex in charge of?

texture, shape recognition, sensory memory, and bilateral integration