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Quiz: How Doctors Examine the Brain

Test your understanding of Chapter 16. Choose the best answer, then click Show Answer to check.

Question 1

A doctor strokes the outer edge of an adult patient's sole. Which response is the Babinski sign?

  1. The big toe curls down and the other toes curl in
  2. The big toe goes up and the other toes fan out
  3. The foot pulls away quickly because the stroke tickles
  4. The knee straightens with a brisk kick
Show Answer

The correct answer is B. An upgoing big toe with fanning of the other toes is the Babinski sign, which in adults points to damage along the corticospinal tract. A downgoing toe (A) is the normal adult response, and a knee kick (D) is the knee-jerk stretch reflex, a different test.

Concept Tested: Reflex Testing Bloom's Level: Remember

Question 2

Which imaging method builds cross-sectional pictures from X-rays passed through the head?

  1. Magnetic resonance imaging (MRI)
  2. Positron emission tomography (PET)
  3. Electroencephalography (EEG)
  4. Computed tomography (CT)
Show Answer

The correct answer is D. CT spins an X-ray source around the head, and a computer turns the measurements into slices. MRI (A) is a common mix-up, but it uses a strong magnet and radio waves, not X-rays.

Concept Tested: Computed Tomography (CT) Bloom's Level: Remember

Question 3

Where is the needle usually placed for a lumbar puncture in an adult?

  1. Between the L3 and L4 (or L4 and L5) vertebrae in the lower back
  2. Between the C1 and C2 vertebrae in the neck
  3. Between the T4 and T5 vertebrae at the level of the nipples
  4. Directly into the spinal cord at the L1 vertebra
Show Answer

The correct answer is A. In adults, the spinal cord usually ends around L1, so a needle at L3-L4 or L4-L5 reaches cerebrospinal fluid among loose nerve roots without hitting the cord. Option D is the mistake the procedure is designed to avoid: the needle never goes into the cord.

Concept Tested: Lumbar Puncture Bloom's Level: Remember

Question 4

What does functional MRI (fMRI) actually detect when a brain area becomes more active?

  1. The electrical spikes of individual neurons, millisecond by millisecond
  2. A radioactive sugar tracer building up in busy cells
  3. Changes in blood oxygen that follow the activity by a few seconds
  4. Changes in bone density around the active area
Show Answer

The correct answer is C. fMRI measures the BOLD (blood-oxygen-level dependent) signal: active areas receive extra oxygen-rich blood, and the response peaks a few seconds later. Option A describes what many people assume fMRI does, but recording fast electrical activity is closer to what EEG does. Option B describes FDG-PET.

Concept Tested: Functional MRI Bloom's Level: Understand

Question 5

Why does a stroke in one cerebral hemisphere usually leave the forehead able to wrinkle on both sides?

  1. The nerve cells controlling the forehead receive signals from both hemispheres
  2. The forehead muscles are controlled by the trigeminal nerve, not the facial nerve
  3. Strokes never affect the face, only the arms and legs
  4. The forehead is controlled by the spinal cord, which strokes don't reach
Show Answer

The correct answer is A. The forehead's nerve cells get input from both hemispheres, so the healthy hemisphere keeps the forehead working. The lower face gets input mainly from the opposite hemisphere, so it droops. Option B confuses the trigeminal nerve (facial feeling and chewing) with the facial nerve (facial expression).

Concept Tested: Cranial Nerve Exam Bloom's Level: Understand

Question 6

An FDG-PET scan of the brain is mainly useful because it shows:

  1. The fine structure of gray and white matter, without radiation
  2. Fresh bleeding, faster than any other test
  3. The brain's electrical rhythms during sleep
  4. Which brain areas are taking up a glucose-like tracer, a sign of how much fuel they use
Show Answer

The correct answer is D. FDG is a slightly modified glucose molecule, so FDG-PET shows which areas are using fuel and which have gone quiet. Option A describes MRI (and PET does involve a small radiation dose), and option B describes a strength of CT.

Concept Tested: PET Scan Bloom's Level: Understand

Question 7

A 60-year-old man arrives with sudden weakness of his right arm. Before any scan, the nurse's finger-stick test shows a very low blood sugar. What is the best interpretation?

  1. Low blood sugar proves he is not having a stroke, so no further workup is needed
  2. Low blood sugar is a known stroke mimic, so it should be treated and the patient reassessed
  3. Low blood sugar means the stroke must be hemorrhagic
  4. Blood sugar is unrelated to neurological symptoms and can be ignored
Show Answer

The correct answer is B. Hypoglycemia can cause stroke-like symptoms, so it belongs on the differential diagnosis and is checked early because it's quick to test and fix. Option A goes too far: finding a mimic doesn't automatically rule out a stroke, so the doctor reassesses after correcting the sugar.

Concept Tested: Differential Diagnosis Bloom's Level: Apply

Question 8

During the mental status exam, a patient is alert and follows commands but speaks haltingly and can't name a pen or a watch. Which part of the brain is most likely affected?

  1. The cerebellum
  2. The right (usually non-dominant) hemisphere
  3. The left (usually dominant) hemisphere
  4. The lumbar spinal cord
Show Answer

The correct answer is C. Trouble with language (aphasia) points to the dominant hemisphere, which is the left one in most people. The right hemisphere (B) is a tempting choice, but right-hemisphere damage more typically causes neglect of the left side of space, not aphasia.

Concept Tested: Mental Status Exam Bloom's Level: Apply

Question 9

A patient has normal thinking, a normal face, and normal arms. Both legs are weak and stiff, the knee and ankle reflexes are brisk, both big toes go up, and pinprick feels dull from the belly button down on both sides. Where is the lesion?

  1. The left cerebral hemisphere
  2. The peripheral nerves of both legs
  3. The brainstem
  4. The thoracic spinal cord
Show Answer

The correct answer is D. Upper motor neuron signs in both legs (brisk reflexes, Babinski signs), normal arms and face, and a sensory level near the T10 dermatome all point to the thoracic spinal cord. Peripheral nerve damage (B) would reduce reflexes, not make them brisk.

Concept Tested: Lesion Localization Bloom's Level: Analyze

Question 10

A patient has sudden numbness and mild weakness of one hand that is still present. In the emergency room, the non-contrast CT is normal. The team suspects a small ischemic stroke. Which test is most likely to show it?

  1. MRI with diffusion-weighted imaging
  2. A repeat non-contrast CT ten minutes later
  3. An EEG
  4. A lumbar puncture
Show Answer

The correct answer is A. Diffusion-weighted MRI can show an ischemic stroke earlier than plain CT and is especially good for small strokes. A repeat CT minutes later (B) is unlikely to help, because early ischemic strokes often look normal on CT; the CT's main early job is to rule out bleeding.

Concept Tested: Magnetic Resonance Imaging Bloom's Level: Analyze