Vogel 1 Flashcards
a. Contain intrafusal muscle fibers
b. Sensory innervation from Type Ia and Type II fibers
c. Encode rate (Ia) and degree (II) of muscle stretch
d. Required for proprioception (position sense)
Muscle spindles
a. Sensory innervation from Type Ib fibers
b. Encode force of muscle contraction
c. Required for proprioception
Golgi tendon organs
a. Distributed to intramuscular connective tissue and investing fascia
b. “Naked” terminals of Type III and IV (C) fibers
c. Pain sensation (nociception) caused by direct injury or by accumulation of metabolites (e.g. lactic acid)
Free nerve endings in muscle
a. Abundant in joint ligaments and capsules
b. Pain sensation (nociception) when joint is strained
c. “Naked” terminals of Type IV (C) fibers
Free nerve endings in joints
a. Located in basal epithelium of epidermal ridges
b. Mechanoreceptor
c. Slowly-adapting = discharge continuously in response to sustained pressure
d. Type II fiber
e. Sensitive to edges of objects held in hand; crucial to reading Braille
Merkel cell complexes
a. “Naked” terminals of myelinated axons applied to outer root sheath epithelium
b. Mechanoreceptor
c. Rapidly-adapting = fire when hairs are initially bent, but not when bent position is sustained
Follicular nerve endings
a. Encapsulated stacks of glial lamellae with sensory axons (Type II) zigzagging in-between
b. Rapidly-adapting cutaneous mechanoreceptors
c. Numerous in finger pads
d. For delicate “detective work” on textured and embossed surfaces (crucial to reading Braille)
Meissner corpuscles
a. Encapsulated, slowly-adapting cutaneous mechanoreceptor
b. Type II fiber
c. Respond to drag (shearing stress)
Ruffini endings
a. Encapsulated, rapidly-adapting subcutaneous mechanoreceptors
b. Consist of onion-like layers of perineurial epithelium surrounding a single”naked” axon terminal (Type II fiber)
c. Especially sensitive to vibration
d. Act as “event detectors” during object manipulation
Pacinian corpuscles
a. Some sensory axons shed perineurial and myelin sheaths as they approach skin surface
b. “Naked” axons and branches terminate between collagen bundles (dermal nerve endings) or within epidermis (epidermal nerve endings)
c. Type III and IV (C) fibers
d. Modalities
1) Thermoreceptors: sensitive to warm or cold temperature stimuli applied to areas of skin
2) Nociceptors (pain-transducing)
a) Respond to severe mechanical deformation of skin (e.g. pinch with forceps)
b) Polymodal nociceptors: can transduce mechanical deformation, intense heat, intense cold, and irritant chemicals (C)
Free nerve endings
