Afferents for stretch reflexes are carried
by which fibers?
a) Aa
b) Ay
c) Type B
d) Type C
Correct Answer - A
Ans. A. Aa
[Ref Ganong 24th/e p. 229]
Sensory innervation (afferent) of muscle spindle:
Two types of sensory nerve fibers (afferent) originate from the
intrafusal fibers :
Annulospiral (Primary) ending are wound around the central region
of both nuclear bag fiber and nuclear chain fiber.
These are Aα (or Iα) fibers.
Flower-spray (Secondary) endings innervate the peripheral parts
(ends) of nuclear chain fiber.
These are Aβ or (or II) fibers