Question 1

Alexi was in a car accident. After the accident, Alexi has difficulty maintaining posture as he walks. Which motor pathway do you suspect was injured?

Accepted Answer

The answer of Alexi was in a car accident. After...

Question 2

An inability to raise one's right arm could be interpreted as a sign of potential damage to the

Accepted Answer

The answer of An inability to raise one's right arm...

Question 3

Alyse is standing on a balance beam. Which motor pathway carries information to help her maintain her balance?

Accepted Answer

The vestibulospinal tract carries information about balance and equilibrium from the inner ear to the spinal cord to help maintain balance, and is therefore the best choice for this scenario.

Question 4

Which part of the brain most directly controls the execution of a movement?

Accepted Answer

The primary motor cortex is responsible for the direct execution of movement by sending signals through the descending motor pathways to the spinal cord and ultimately to the muscles. While the other brain regions listed (basal nuclei, cerebellum, and premotor cortex) all contribute to the planning and coordination of movement, the primary motor cortex is the area that directly controls muscle contraction.

Question 5

Axons of the lateral corticospinal tract decussate at what level of the nervous system?

Accepted Answer

The axons of the lateral corticospinal tract, which originate in the primary motor cortex and control voluntary movement of the limbs, torso, and digits, decussate (cross over to the other side of the body) at the level of the medulla oblongata. This is why damage to one side of the brain can result in weakness or paralysis on the opposite side of the body.

Question 6

Which of the following symptoms would be associated with a lesion in the primary motor cortex of the cerebrum?

Accepted Answer

The primary motor cortex is responsible for voluntary movements of the body, including the fingers. A lesion in this area may result in difficulty with voluntary contraction and relaxation of the fingers.

Question 7

Reflexive movements of the head, for example to a visual or auditory stimulus, are mediated by the ______tract of the indirect pathways.

Accepted Answer

The answer of Reflexive movements of the head, for example...

Question 8

Maintenance of posture in response to changes in balance is mediated by the ______tract of the indirect pathways.

Accepted Answer

The answer of Maintenance of posture in response to changes...

Question 9

If the left, lateral corticospinal tract was destroyed below the brainstem in a car accident, what symptoms would you expect the individual to suffer?

Accepted Answer

The left lateral corticospinal tract controls voluntary movements of the right side of the body. Damage to it would result in paralysis of muscles on the left side. Loss of somatic sensation is associated with damage to the sensory pathways and not the corticospinal tract.

Question 10

Which of the following is NOT one of the indirect motor pathways?

Accepted Answer

The corticospinal pathway is a direct motor pathway involved in voluntary motor control, while the other pathways listed (reticulospinal, rubrospinal, tectospinal, and vestibulospinal) are all indirect motor pathways involved in various aspects of motor function such as posture, balance, and coordination.

Question 11

More area in the primary motor cortex is devoted to controlling larger muscles.

Accepted Answer

More area in the primary motor cortex is devoted to controlling body parts that require fine motor skills, not necessarily larger muscles. This is why areas like the hands and face have more cortical representation than their relative size would suggest.

Question 12

Most of the corticospinal axons decussate in the medulla.

Accepted Answer

Most of the corticospinal axons decussate (cross over) to the opposite side of the body in the medulla oblongata of the brainstem.

Question 13

Different muscles in the body have different amounts of primary motor cortex devoted to controlling them with some having large areas and other having small areas.

Accepted Answer

This statement is true. The primary motor cortex is responsible for controlling voluntary movements in the body and the amount of cortex dedicated to controlling a particular muscle group is proportional to the complexity and fine control required for that muscle group. For example, the fingers and tongue have large areas of primary motor cortex dedicated to them, while the trunk and limbs have fewer dedicated areas.

Question 14

The lateral corticospinal axons decussate in the spinal cord.

Accepted Answer

The lateral corticospinal axons decussate at the medulla oblongata, not in the spinal cord.

Question 15

Damage to the midbrain could affect all motor components of brain stem, EXCEPT

Accepted Answer

Damage to the midbrain would not affect the vestibular nuclei as they are located in the medulla oblongata and pons, which are lower brainstem structures. The other options (red nucleus, reticular formation, superior colliculus) are all located in the midbrain and could therefore be affected by damage to this region.

Question 16

A person has a complete inability to voluntarily move the muscles on the left side of their face, but the right side is normal or close to normal. In what area might be the damage leading to these symptoms?

Accepted Answer

The answer of A person has a complete inability to...

Question 17

After many years of playing the same song night after night, a piano player is now unable to recall and produce the movements of his hands needed to play the song now. The area of his brain most likely to be failing now is the

Accepted Answer

The premotor cortex is responsible for planning and executing movements, specifically those related to learned and repetitive movements such as playing a familiar song on the piano. Damage or dysfunction in this area can result in difficulty recalling the motor movements necessary to execute the task. The cerebellum is also involved in motor control but primarily plays a role in coordinating movement rather than planning and execution. The post-central gyrus and pre-central gyrus are primarily involved in sensory and motor processing respectively, but not specifically related to learned motor movements such as playing a specific song on the piano. The left temporal lobe is primarily associated with language processing, not motor function.

Question 18

Saccades are a result of activity in which part of the nervous system?

Accepted Answer

Saccades are rapid eye movements that shift the gaze from one point to another. These movements are controlled by activity in the superior colliculus, a structure located in the midbrain that is involved in visual processing and motor control.

Question 19

Shandra was involved in a car accident and damaged her spinal cord. A physical exam shows that she has difficulty controlling muscles in her trunk and proximal parts of her limbs. Which motor pathway do you suspect was injured?

Accepted Answer

The ventral corticospinal tract is responsible for controlling muscles in the trunk and proximal parts of the limbs. Damage to this pathway can cause difficulty controlling these muscles, which is consistent with Shandra's symptoms.

Question 20

The two direct motor outputs from the cortex are the

Accepted Answer

The corticobulbar and corticospinal pathways are the two main direct motor outputs from the cortex. The corticobulbar pathway controls movements of the face and head through connections with cranial nerves in the brainstem, while the corticospinal pathway controls movements of the body and limbs through connections with the spinal cord. The other answer choices are incorrect as they refer to different pathways and connections.

Quiz 12: Control of Body Movement