Question 1

A patient presents with a painful, unilateral vesicular rash distributed along a single dermatome. Which of the following best explains the underlying mechanism?

Accepted Answer

The varicella-zoster virus reactivates from latency in the posterior root ganglion, affecting sensory neurons in a specific dermatome.

Question 2

Which of the following best describes the difference between divergence and convergence in neuronal pools?

Accepted Answer

Divergence is when one neuron sends output to many neurons, while convergence is when multiple neurons synapse on a single neuron.

Question 3

A patient steps on a sharp object and immediately withdraws their foot while the opposite leg extends to support their weight. Which reflexes are involved in this response?

Accepted Answer

Withdrawal (flexor) reflex and crossed extensor reflex, both of which are polysynaptic.

Question 4

Which of the following statements about the blood-brain barrier (BBB) is correct?

Accepted Answer

The BBB is primarily formed by tight junctions between capillary endothelial cells, with astrocyte end-feet regulating permeability.

Question 5

A patient with a lesion in the medulla oblongata may experience which of the following clinical consequences?

Accepted Answer

Impaired cardiovascular and respiratory regulation due to disruption of vital reflex centers.

Question 6

Which of the following best describes the flow of cerebrospinal fluid (CSF) through the ventricular system?

Accepted Answer

Lateral ventricles $$\rightarrow$$ interventricular foramina $$\rightarrow$$ third ventricle $$\rightarrow$$ cerebral aqueduct $$\rightarrow$$ fourth ventricle $$\rightarrow$$ apertures $$\rightarrow$$ subarachnoid space $$\rightarrow$$ arachnoid granulations $$\rightarrow$$ venous sinuses

Question 7

A patient is unable to perform fine, skilled movements with their right hand. Which pathway is most likely affected?

Accepted Answer

Left lateral corticospinal tract, which decussates at the medullary pyramids.

Question 8

Which of the following is TRUE regarding the organization of the cerebral cortex?

Accepted Answer

The precentral gyrus contains the primary motor cortex, while the postcentral gyrus contains the primary somatosensory cortex.

Question 9

Which of the following best explains why referred pain occurs?

Accepted Answer

Visceral and somatic sensory inputs converge on overlapping CNS circuits, causing visceral pain to be perceived at a somatic site.

Question 10

A patient with damage to the substantia nigra is most likely to experience which of the following symptoms?

Accepted Answer

Difficulty initiating voluntary movements and tremors, as seen in Parkinson's disease.

Question 11

Which of the following statements about sensory adaptation is correct?

Accepted Answer

Tonic receptors adapt slowly and continue to respond to a sustained stimulus, while phasic receptors adapt rapidly and respond mainly to changes in stimulus.

Question 12

Which of the following best describes the difference between the posterior column–medial lemniscus pathway and the spinothalamic pathway?

Accepted Answer

The posterior column–medial lemniscus pathway carries fine touch, vibration, and conscious proprioception, crossing in the medulla, while the spinothalamic pathway carries pain and temperature, crossing in the spinal cord.

Question 13

A patient is unable to maintain balance and coordination but has no muscle weakness. Which brain region is most likely affected?

Accepted Answer

Cerebellum, which is responsible for coordination, timing, and error correction of movement.

Question 14

Which of the following cranial nerves is correctly matched with its primary function?

Accepted Answer

CN VIII (vestibulocochlear): hearing and equilibrium

Question 15

Which of the following best describes the function of the basal nuclei?

Accepted Answer

They facilitate the initiation and selection of intended movements and suppress unwanted motor programs.

Question 16

A patient has a lesion affecting the anterior corticospinal tract. Which of the following deficits would most likely be observed?

Accepted Answer

Impaired control of axial and proximal limb muscles, often with bilateral effects.

Question 17

Which of the following statements about the organization of gray and white matter in the cerebrum is correct?

Accepted Answer

The cerebral cortex is composed of gray matter, while deep white matter contains axon tracts connecting different regions.

Question 18

Which of the following best explains the concept of a sensory homunculus?

Accepted Answer

It is a map of the body on the postcentral gyrus, with area proportional to sensory receptor density rather than body size.

Question 19

A patient is unable to abduct their right eye. Which cranial nerve is most likely damaged?

Accepted Answer

CN VI (abducens), which innervates the lateral rectus muscle.

Question 20

Which of the following best describes the difference between sensation and perception?

Accepted Answer

Sensation is the arrival of sensory information in the CNS, while perception is the conscious awareness and interpretation of that information.

A&P I Exam 3 Study Guide: Spinal Cord, Brain, and Sensory/Motor Pathways

Study Guide - Practice Questions

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