PRACTICE QUESTIONS

1. Which of the following would not be considered an upper motor neuron?

a. Bulbospinal motor neurons

b. Corticospinal motor neurons

c. Ventral horn α motor neurons of the spinal cord

d.

2. You examine a dog that is unable to stand and bear weight on the right rear leg. The right rear leg is much smaller in diameter than the left rear leg. Pinching the toe on the left rear leg results in withdrawal of the left rear leg, but pinching the toe on the right rear leg results in no movement of the right rear leg. The proprioceptive placing response to the left rear leg is normal, but to the right rear leg it is absent. Where is this dog’s pathological lesion?

a. Lower motor neuron to the right rear leg

b. Lower motor neuron to the left rear leg

c. Upper motor neuron controlling the right rear leg

d. Upper motor neuron controlling the left rear leg

e. Neuromuscular synapse of the left rear leg

3. You examine a dog that is bright, alert, and responsive. She can stand and bear weight on both front legs, but she cannot stand or bear any weight on the back legs. Her knee jerk and toe-pinch withdrawal reflexes are normal in all four legs. There is no atrophy. The proprioceptive positioning response is normal in the front legs but absent in both rear legs. Injecting acetylcholinesterase-inhibiting drugs causes no change in the clinical signs. Where is this dog’s pathological lesion most likely located?

a. Neuromuscular junction

b. Cervical spinal cord (spinal cord of the neck)

c. Spinal cord between the front and rear legs (thoraco­lumbar spinal cord)

d. Lower motor neurons to the rear legs

e. Brainstem

4. You examine a dog that is bright, alert, and responsive but unable to stand on any of the four legs. Toe-pinch and knee jerk local (segmental) reflexes are normal in all four legs. There is no atrophy.

a. Cervical spinal cord (spinal cord in the neck)

b. Spinal cord between the front and rear legs (thoraco­lumbar spinal cord)

c. Lower motor neurons to all four legs

d. Neuromuscular junction

5. You are presented with a horse that is unable to stand or support any weight on the hind legs. You electrically stimulate both the sciatic and the femoral nerve with a sufficient stimulus, but neither stimulation results in mus­cular contraction. However, direct stimulation of both the gastrocnemius and the quadriceps femoris muscle of the rear leg results in muscular contraction. From these observations, what do you logically conclude to be the location of this horse’s pathological lesion?

a. Upper motor neurons controlling the rear legs

b. Lower motor neurons to the rear legs

c. Neuromuscular synapses of the rear legs

d. Muscles of the rear legs

e. Either b or c

6. You examine a cat that cannot Ixar weight on the hind legs. The cat is bright, alert, and responsive. Atrophy is present in the back legs. Cranial nerve reflexes are within normal limits, as are segmental reflexes and the proprioceptive positioning responses of the front legs. Knee jerk and toe­pinch withdrawal reflexes are absent in the hind legs. What is the most likely location for this cat’s pathological lesion?

a. Brainstem

b. Cervical spinal cord (spinal cord in the neck)

c. Thoracolumbar spinal cord (spinal cord between the front and rear legs)

d. Lower motor neurons to the front legs

e. Lower motor neurons to the hind legs