Unit XI (55-62) - The Nervous System - Motor and Integrative Neurophysiology Flashcards
Activation of the Golgi tendon organ of a given muscle:
a. Monosynaptically produces excitatory post synaptic potential (EPSP) on the α motor neuron that returns to that muscle.
b. Is most effectively produced by lengthening of the extrafusal fibers of that muscle.
c. Polysynaptically produces IPSPs on the α motor neuron that returns to that muscle.
d. Polysynaptically produces EPSPs on the α motor neuron that returns to that muscle.
e. Activates motor neurons that return to the Golgi tendon organ itself.
C. Polysynaptically produces Inhibitory post synaptic potentials on the α motor neuron that returns to that muscle.
Cunningham Ch. 8
Golgi tendon organ - senses tension, it is a local circuit that directly inhibits the individual muscle without affecting the adjacent muscles.
Signals transmitted through large rapidly conducting Type IB nerve fibers
Gamma (γ) motor neurons:
a. Innervate and produce contraction of the equatorial
(middle) region of an intrafusal fiber.
b. Have their cell bodies in the dorsal horn of the spinal cord.
c. Are never activated at the same time as α motor neurons.
d. Can regulate the sensitivity of the muscle spindle sensory organ.
e. Innervate and regulate the sensitivity of the Golgi tendon
organ.
D. Can regulate the sensitivity of the muscle spindle sensory organ.
Cunningham Ch. 8
Gamma - smaller fibers, in less quantities than alpha , innervate intrafusal fibers
Which of the following is not characteristic of the muscle
spindle?
a. Encapsulated intrafusal fibers
b. Sensitivity to muscle tension
c. Sensitivity to dynamic stretching of the muscle
d. Lying parallel to the extrafusal muscle fibers
e. Sensitivity to steady-state length of the muscle
B. Sensitivity to muscle tension
Cunningham Ch. 8
If the distance between the origin and insertion tendons is increased (the muscle is stretched), what happens to the frequency of action potentials along the sensory axons leaving the muscle spindles in that muscle?
a. Increases
b. Decreases
c. Does not change
A. Increases
Cunningham Ch. 8
Hair cells similar to those of the organ of Corti are important for the function of which two of the following sensory organs?
a. Muscle spindle
b. Retina
c. Crista ampullaris
d. Golgi tendon organ
e. Utricular macula
C and E
Crista ampullaris and Utricular macula
Cunningham Ch. 17
Which one of the following cranial nerves transmits sound to the brain?
a. Second
b. Seventh
c. Eighth
d. Tenth
C. VIII
Cunningham Ch. 17
A motor neuron pool located most laterally in the ventral horn of the spinal cord is most likely to operate a muscle controlling movement of the:
a. Proximal limb.
b. Neck.
c. Distal limb.
d. Abdomen
C. Distal limb
Cunningham Ch. 10
Which of the following is true regarding decerebrate rigidity?
a. It can result from severe forebrain disease.
b. Disruption of the cortical control of medullary reticulospinal neurons is a major contributor to the condition.
c. It can result in a fixed, rigid, hobbyhorse-like posture in the quadruped.
d. Removal of normal inhibition to some of the antigravity
muscles contributes to the condition.
e. All of the above are true.
E. All of the above
Cunningham Ch. 10
Which of the following descending brainstem motor pathways controls distal limb musculature associated with skilled movement?
a. Vestibulospinal tract
b. Rubrospinal tract
c. Reticulospinal tract
d. Corticospinal tract (pyramidal)
B. Rubrospinal tract (extrapyramidal)
Cunningham Ch. 10
Vestibulospinal tract and Reticulospinal tract - important for maintaining the body upright against the pull of gravity
The corticospinal (pyramidal) tract, in general, initiates what form of movement?
a. Antigravity movement
b. Postural adjustment
c. Skilled, voluntary, mostly flexor movement
d. Tremulous, jerky movement
e. None of the above
C. Skilled, voluntary, mostly flexor movement
Cunningham Ch. 10
You are presented with a dog with a dense weakness, and proprioceptive placing reaction deficit, of his left front and left back legs. A single pathological site could cause these signs if it were located in the:
a. Left side of the cervical spinal cord.
b. Left cerebral cortex.
c. Right cerebral cortex.
d. Either a or b
e. Either a or c
E. A or C
Cunningham Ch. 10
The receptor organ detecting rotary acceleration and deceleration of the head is located in the:
a. Utricle
b. Saccule
c. Ampulla of the semicircular duct
d. Scala media of the cochlea
e. Vestibular nuclear complex
C. Ampulla of the semicircular duct
because it has the endolymph - fluid remains stationary while the semicircular ducts rotates with the head.
Cunningham Ch. 11
utricle - linear acceleration. determines the orientation of the head when the head is upright (horizontal)
saccule - detects orientation of the head when lying down (vertical)
- Which two of the following are not generally associated with the macula?
a. Otoliths
b. Cupula
c. Detection of linear acceleration of the head
d. Hair cells
e. Normal nystagmus
B and E
Cupula and Normal nystagmus
Cunningham Ch. 11
You are presented with a dog with a head tilt, compulsive
circling, and spontaneous nystagmus. The most likely site of this dog’s pathological lesion is the:
a. Oculomotor nucleus.
b. Cerebral cortex.
c. Vestibular system.
d. Cervical spinal cord.
e. Spinal accessory (eleventh cranial) nerve.
C. Vestibular system
Cunningham Ch. 11
Which one of the following statements is false?
a. All hair cells of a single utricle are oriented in the same direction with respect to their cilia.
b. In a single vestibular hair cell, displacement of the cilia toward the largest cilium increases the firing rate of the hair cell’s associated sensory neuron.
c. The axons of sensory neurons synaptically associated with vestibular hair cells form the eighth cranial nerve.
d. A gelatinous layer is associated with the vestibular macula.
e. The vestibular nuclear complex is located in the brainstem.
A. All hair cells of a single utricle are oriented in the same direction with respect to their cilia.
Cunningham Ch. 11
- If a normal dog is sitting on a piano stool and I start to spin (accelerate) the stool to the right, which two of the following will be false regarding the observed nystagmus?
a. The pattern of nystagmus observed at the start of rotation will be seen in reverse briefly after the spinning is abruptly stopped.
b. An intact medial longitudinal fasciculus (MLF) is important for producing the nystagmus.
c. The nystagmus will continue long after constant velocity is achieved.
d. The eyes will drift slowly to the left, as far as they can go, and then flip rapidly back to the right.
e. Nystagmus will often be observed long after the spinning has stopped, while the dog is stationary.
C & E
Cunningham Ch. 11
Which brain structure serves as the major controller of the limbic system? A. Hypothalamus B. Hippocampus C. Amygdala D. Mammillary body E. Fornix
A. Hypothalamus
The hypothalamus, despite its small size, is the most important control center for the limbic system. It controls most of the vegetative and endocrine functions of the body and many aspects of behavior.
Guyton 13 ed. p 755
Which reflex is correctly paired with the sensory structure that mediates the reflex?
A. Autogenic inhibition - muscle spindle
B. Reciprocal inhibition - Golgi tendon organ
C. Reciprocal inhibition - Pacinian corpuscle
D. Stretch reflex - muscle spindle
E. Golgi tendon reflex - Meissner Corpuscle
D. The stretch reflex is mediated by muscle spindles. Autongenic inhibition involves Golgi tendon organs. Reciprocal inhibition is also related to muscle spindles.
Guyton 13 ed. p 698-699
Stimulation of which subcortical area can lead to contraction of a single muscle or small groups of muscles? A. Dentate nucleus of the cerebellum B. Ventrobasal complex of the thalamus C. Red nucleus D. Subthalamic nucleus E. Nucleus accumbens
C. Red nucleus
The magnocellular portion of the red nucleus has a somatographic representation of all the muscles of the body, similar to the motor cortex. Stimulation of this area in the red nucleus results in contraction of a single muscle or small groups of muscles.
Which of the following is not associated with paradoxical vestibular disease?
A. Lesion in flocculonodular lobe
B. CP deficits on side of the lesion
C. Head tilt away from the lesion
D. Fast phase nystagmus toward the lesion
D. Fast phase toward the lesion
Paradoxical vestibular - loss of inhibitory influence on the vestibular nuclei –> overexcitation on the side of the lesion, vestibular signs away from the lesion and CP deficits on the side of the lesion.
1. Which of the following is principally involved in planning ahead for the next appropriate movement? a. Vestibulocerebellum b. Spinocerebellum c. Cerebrocerebellum d. Archicerebellum e. Both a and b
C. Cerebrocerebellum
Cunningham Ch 12
Which of the following is true regarding cerebellar Purkinje cells?
a. They are located in the cerebellar cortex.
b. They have large cell bodies.
c. They have an extensive dendritic tree.
d. When active, they inhibit the activity of cells in deep cerebellar nuclei, whose axons leave the cerebellum.
e. All the above.
E. all of the above
Cunningham Ch 12
Loss of the cerebellum causes loss of the muscle stretch reflex.
a. True
b. False
False
Cunningham Ch 12
Cats with congenital malformations of the cerebellum often have ataxia, intention tremor, and wide gait.
a. True
b. False
True
Cunningham Ch 12
As they leave the spinal cord and course peripherally to skeletal muscle, the axons of motor neurons must pass through which of the following structures? A. Posterior column B. Posterior root C. Posterior horn D. Anterior root E. Ventral White commissure
D. Axons of motor neurons in the anterior horn exit the spinal cord through the anterior root. The posterior root serves as the entry point for sensory fibers coming into the posterior horn region of the spinal cord. The posterior column and ventral white commissure are fiber tracts located solely within the spinal cord.
Guyton 13th ed p. 695
