QUIZ 8 Flashcards
a motor neuron pool consists of:
-all of the motor neurons that project to a given muscle
-all of the motor neurons that project to a given limb
-all of the motor neurons within a single segment of spinal cord
-a single motor neuron and all of its afferent interneurons
-a single motor neuron and all of the muscles it innervates
all of the motor neurons that project to a given muscle
a specialized motor unit, with an average size of three muscle fibers, controls:
-finger movements
-the large, fast contracting muscles used in sprinting
-postural muscle
-eye muscles
eye muscles
which of the following statements about the organization of muscles and motor neurons is false?
-successive stimulation of muscles can produce force levels that build up over time
-the fastest, strongest muscle fibers can produce the most sustained force output
-large motor neurons are recruited only at higher levels of stimulus intensity
-red muscle fibers contract slowly and produce the smallest amount of force
the fastest, strongest muscle fibers can produce the most sustained force output
the condition called “fused tetanus” refers to:
-a sustained maximal contraction due to high frequency input to motor unit firing
-lockjaw symptoms resulting from exposure to the tetanus toxin
-the response of single muscle fibers to a single action potential input
-an excessive contraction that results in the fusing together of muscle fibers
a sustained maximal contraction due to high frequency input to motor unit firing
group 1a afferents are coiled around ____ fibers
-all extrafusal muscle fibers
-only S-type extrafusal muscle fibers
-both nuclear bag and nuclear chain fibers
both nuclear bag and nuclear chain fibers
if the muscle is actively contracted and shortens during voluntary movement, which of the following would you expect to increase their discharge rate?
(select multiple)
-golgi tendon organs
-gamma motor neurons
-muscle spindles
-alpha motor neurons
-golgi tendon organs
-gamma motor neurons
-alpha motor neurons
in a stretch reflex with a high gain, a ____ stretch of a muscle would lead to ____ increase in extrafusal muscle tension
-small; a large
-small; no
-large; a small
-large; no
small; a large
gamma (γ) motor neuron firing rates are typically high
(select multiple)
-during difficult and precise movements (walking on a narrow beam)
-during voluntary stretching
-during unpredictable conditions (standing on a moving bus)
-during difficult and precise movements (walking on a narrow beam)
-during unpredictable conditions (standing on a moving bus)
the flexion-crossed extension reflex would occur in response to which activity?
-holding a box steady as more items are added to it
-coordinating your legs to squat
-stimulation of the mesencephalic locomotor region
-stepping on a sharp object
-a knee tap with a reflex hammer
stepping on a sharp object
the local circuits in the spinal cord that are fully capable of controlling the timing and coordination of complex locomotion are called ____
central pattern generators