Motor Reflexes and Modification Flashcards
Myotatic reflex is a stretch reflex that is meant to protect the muscle from tearing due to stretching. Myotactic reflex is a monosynpatic, segmental reflex that is initiated by what strcutre found within the fusiform capsule of muscle fibers?
Muscle spindles
All of the following characteristics is true of the sensory portion of a muscle spindle, EXCEPT which of the following?
A. Non-contractile
B. Portion sensitive to length
C. Has two sensors that are associated with nuclear bag and nuclear chain fibers
D. All the above are correct
All the above are correct
Smaller group II fibers innervate nuclear chain fibers and are sensitive to what?
A. Change in length of muscle
B. Change in how fast the length changes
C. Change in strength of the muscle
D. A and B
Change in length of muscle
Large myelinated group Ia fibers innervate nuclear bag fibers and are sensitive to what?
A. Change in length of muscle
B. Change in how fast the length changes
C. Change in strength of the muscle
D. A and B
A and B
What motor neuron controls the length of the sensory portion of skeletal muscle, and innervate intrafusal muscle fibers?
Gamma motor neurons
What is the name of the polysynaptic, segmental reflex that appears to abruptly relax a contracted muscle?
Golgi Tendon Reflex
Where would you find the Golgi Tendon Organ?
What fiber type is it associated with?
Tendons
Ib fibers
Which of the following is true of the myostatic reflex, and NOT the golgi tendon reflex?
A. Initiated by golgi tendon
B. activated by passive stretch of the muscle
C. arupt relaxation of contracted muscle to prevent muscle damage
D. polysynaptic reflex
activated by passive stretch of the muscle
Decorticate posturing is due to which of the following?
A. Hyperpolarization of spinal neurons due to loss of excitatory input from the cortex
B. Loss of cortical inputs, most commonly caused by lesions of internal capsule
C. Loss of input from all structures rostral to the pons (caudal to red nucleus)
D. None of the above
Loss of cortical inputs, most commonly caused by lesions of internal capsule
Contraction of all anti-gravity muscles is seen in what type of posturing?
Decerbrate posture
Select all of the following that relate to Rigidity, and NOT spasticity.
A. Patient resists a passive stretch of their muscles
B. Contraction of muscles in the absence of other stimuli
C. Alpha-motor neuorns are continually active
D. Hyperactive myotactic reglec due to increased gamma motor neuron firing
E. Caused by damage to cortex that abolishes activation of the brainstem inhibitory region
B. Contraction of muscles in the absence of other stimuli
C. Alpha-motor neuorns are continually active
NOTE: Rigidity is caused by loss of cortical influence that inhibits a medullary input to the alpha-motor neurons
Which of the following actions requires the cortex?
A. Stretch (myotatic) reflex
B. Crossed Extensor
C. Eye/Head Movement
D. Hopping Reaction
E. Righting reflex
- A. Stretch (myotatic) reflex: spinal reflex*
- B. Crossed Extensor: spinal reflex*
- C. Eye/Head Movement: brainstem/Midbrain*
D. Hopping Reaction
E. Righting reflex: Brainstem/Midbrain
