Anatomy and Physiology of the Head, Brain, and Spine Practice Questions

25 multiple-choice questions on Anatomy and physiology of the head, brain, and spine for paramedic and EMT students, from Chapter 35 (Head and Spine Trauma). Read each question, pick your answer, then tap Show answer to check it and read the explanation.

25 practice questions

1. A depressed skull fracture lies directly over one of the large dural venous sinuses. This location is dangerous mainly because:

   1. A. The sinus will clot off and stop all flow
   2. B. It is likely to tear the middle meningeal artery
   3. C. The sinus bleeds under high arterial pressure
   4. D. Lifting the fragment may cause hemorrhage
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   Answer: D. Lifting the fragment may cause hemorrhage

   Bone fragments over a dural venous sinus may be plugging a torn sinus, so disturbing them can cause massive bleeding or air embolism. Such fractures are left alone in the field and managed surgically. The middle meningeal artery runs beneath the temporal bone rather than along the sinuses, and sinus bleeding is low-pressure venous bleeding, which is why air can be drawn in. A clot cannot be relied on to seal the tear.

2. Checking the blood glucose of a head-injured patient matters partly because the brain:

   1. A. Needs insulin to move glucose into cells
   2. B. Stores very little glucose of its own
   3. C. Holds enough glycogen for several hours
   4. D. Switches to ketones soon after injury
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   Answer: B. Stores very little glucose of its own

   The brain depends on a constant supply of glucose and oxygen and has minimal stores, so both hypoglycemia and severe hyperglycemia can worsen secondary brain injury, and hypoglycemia can mimic or mask a head injury. Its glycogen reserve lasts minutes, not hours, its glucose uptake does not depend on insulin, and it shifts toward ketones after days of fasting rather than in the hours after an injury.

3. Although the brain is only about 2% of body weight, it consumes approximately what share of the body's oxygen?

   1. A. About 20%
   2. B. About 5%
   3. C. About 50%
   4. D. About 2%
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   Answer: A. About 20%

   The brain receives roughly 15% to 20% of cardiac output and uses about 20% of total oxygen, with almost no stored reserve. That is why a few minutes of hypoxia or hypoperfusion causes lasting damage.

4. The medulla oblongata contains the centers that regulate:

   1. A. Balance, posture, and fine coordination
   2. B. Personality, judgment, and planned movement
   3. C. Heart rate, breathing, and vascular tone
   4. D. Hearing, speech comprehension, and memory
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   Answer: C. Heart rate, breathing, and vascular tone

   The medulla holds the cardiac, respiratory, and vasomotor centers, so compression at the foramen magnum causes apnea and cardiovascular collapse. Balance and coordination belong to the cerebellum.

5. A 34-year-old was struck on the back of the head with a pipe. He is alert but reports he cannot see the left half of his visual field. The area of the brain most likely injured is the:

   1. A. Occipital lobe
   2. B. Frontal lobe
   3. C. Temporal lobe (auditory cortex)
   4. D. Cerebellum
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   Answer: A. Occipital lobe

   The occipital lobe at the back of the cerebrum processes vision, and injury there causes visual field loss even when the eyes are normal. The cerebellum also lies posteriorly but controls coordination, not vision.

6. After a fall, a 60-year-old has a wide-based, staggering gait and cannot touch his finger to his nose, though his strength is normal. This suggests injury to the:

   1. A. Medulla
   2. B. Parietal lobe
   3. C. Cerebellum
   4. D. Frontal lobe
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   Answer: C. Cerebellum

   The cerebellum coordinates movement, balance, and posture, so damage produces ataxia without weakness. The frontal lobe contains the motor cortex, whose injury causes weakness rather than incoordination.

7. A small bruise confined to one cerebral hemisphere rarely causes coma by itself. Coma after head injury implies dysfunction of:

   1. A. The frontal lobe of one hemisphere
   2. B. The cerebellum on one side
   3. C. The spinal cord in the neck
   4. D. The brainstem or both hemispheres
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   Answer: D. The brainstem or both hemispheres

   Consciousness depends on the brainstem's reticular activating system and its connections to both cerebral hemispheres. Coma therefore suggests brainstem compression or injury, or widespread bilateral hemisphere dysfunction (such as diffuse axonal injury). A single small lesion in one lobe, the cerebellum, or the spinal cord does not by itself cause coma.

8. After a significant brain contusion, swelling around the injury typically peaks:

   1. A. Within the first 10 minutes
   2. B. About 1 to 3 days later
   3. C. About 6 hours after impact
   4. D. About 2 weeks later
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   Answer: B. About 1 to 3 days later

   Cerebral edema around contusions develops over hours and usually peaks about 24 to 72 hours after injury, which is one reason patients can worsen after an initially good exam. Swelling is not maximal within minutes, it is still building at 6 hours, and by 2 weeks it is usually resolving rather than peaking.

9. A patient with a head injury has a blood pressure of 120/60 mm Hg and an estimated ICP of 20 mm Hg. The cerebral perfusion pressure is approximately:

   1. A. 40 mm Hg
   2. B. 60 mm Hg
   3. C. 80 mm Hg
   4. D. 100 mm Hg
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   Answer: B. 60 mm Hg

   MAP is the diastolic pressure plus one-third of the pulse pressure: 60 + 20 = 80 mm Hg, and 80 - 20 = 60 mm Hg. The answer 80 mm Hg is the MAP itself, before the ICP is subtracted.

10. Normal intracranial pressure in an adult at rest is about:

    1. A. 0 to 15 mm Hg
    2. B. 20 to 30 mm Hg
    3. C. 35 to 45 mm Hg
    4. D. 60 to 70 mm Hg
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    Answer: A. 0 to 15 mm Hg

    Normal ICP is under about 15 mm Hg, and sustained values above 20 mm Hg are considered elevated and harmful. A range of 60 to 70 mm Hg is closer to a target CPP than to an ICP.

11. The Monro-Kellie doctrine states that because the skull is a rigid box:

    1. A. The brain can swell freely until the cranial sutures separate
    2. B. Cerebral blood flow stays constant despite rising ICP
    3. C. CSF production stops when intracranial pressure rises
    4. D. A rise in one volume must be offset by a fall in another
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    Answer: D. A rise in one volume must be offset by a fall in another

    Brain tissue, blood, and CSF share a fixed volume, so a hematoma or swelling can be accommodated only by pushing out CSF or venous blood. Once those reserves are used up, ICP rises steeply.

12. A 45-year-old has a slowly enlarging subdural hematoma, yet his ICP remains near normal at first. The main early compensation is:

    1. A. Increased production of cerebrospinal fluid
    2. B. Expansion of the adult skull along the cranial suture lines
    3. C. Displacement of CSF and venous blood out of the skull
    4. D. Dilation of the cerebral arteries to add flow
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    Answer: C. Displacement of CSF and venous blood out of the skull

    Early on, CSF is pushed into the spinal subarachnoid space and venous blood leaves the cranium, buffering ICP. Increased CSF production would raise ICP, and adult sutures are fused and cannot expand.

13. Cerebral autoregulation normally keeps cerebral blood flow fairly constant over a mean arterial pressure range of about:

    1. A. 50 to 150 mm Hg
    2. B. 10 to 40 mm Hg
    3. C. 150 to 250 mm Hg
    4. D. 90 to 110 mm Hg
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    Answer: A. 50 to 150 mm Hg

    Within roughly 50 to 150 mm Hg of MAP, cerebral arterioles constrict or dilate to hold flow steady. Below the lower limit flow falls with pressure, and a narrow 90 to 110 range understates the normal reserve.

14. A 28-year-old with a severe TBI has a blood pressure of 86/50 mm Hg. Because autoregulation is often lost after TBI, the main concern is that:

    1. A. The brain will dilate its vessels and keep flow normal
    2. B. Cerebral blood flow will fall along with blood pressure
    3. C. ICP will fall and protect the injured brain from swelling
    4. D. Hypotension will lower the metabolic demand of the brain
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    Answer: B. Cerebral blood flow will fall along with blood pressure

    An injured brain cannot reliably adjust vessel diameter, so flow passively follows systemic pressure and hypotension causes ischemia. Assuming the brain will compensate is exactly the error that leads to secondary injury.

15. A head-injured patient is breathing only 6 times per minute and has an ETCO2 of 62 mm Hg. The rising CO2 will tend to:

    1. A. Constrict cerebral vessels and lower ICP
    2. B. Lower ICP by reducing CSF production
    3. C. Have no effect on cerebral blood volume
    4. D. Dilate cerebral vessels and raise ICP
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    Answer: D. Dilate cerebral vessels and raise ICP

    Carbon dioxide is a potent cerebral vasodilator; hypercapnia increases cerebral blood volume and therefore ICP. Vasoconstriction is the effect of low CO2, which is why hyperventilation lowers ICP.

16. A crew ventilates a brain-injured patient at 30 breaths/min, and the ETCO2 falls to 22 mm Hg. The most likely harmful effect on the brain is:

    1. A. Cerebral vasodilation causing more swelling
    2. B. Rising ICP from retained carbon dioxide
    3. C. Cerebral vasoconstriction causing ischemia
    4. D. Increased CSF production in the ventricles
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    Answer: C. Cerebral vasoconstriction causing ischemia

    Low CO2 constricts cerebral arteries, which lowers ICP but also cuts blood flow, sometimes to ischemic levels. Swelling from vasodilation is the effect of high CO2, the opposite problem.

17. The fold of dura that separates the cerebral hemispheres from the cerebellum, and through which the temporal lobe may herniate, is the:

    1. A. Falx cerebri
    2. B. Falx cerebelli
    3. C. Tentorium cerebelli
    4. D. Arachnoid granulations
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    Answer: C. Tentorium cerebelli

    The tentorium cerebelli is a tent of dura over the cerebellum; the uncus of the temporal lobe herniates through its central notch and compresses cranial nerve III. The falx cerebri is the vertical midline fold between the right and left hemispheres (the site of subfalcine herniation), not the hemisphere-cerebellum boundary. The falx cerebelli is a small fold between the two cerebellar hemispheres. Arachnoid granulations are not dural folds at all; they are where CSF is reabsorbed into the venous sinuses.

18. The large opening at the base of the skull through which the spinal cord joins the brainstem is the:

    1. A. Tentorial notch
    2. B. Sella turcica
    3. C. Jugular foramen
    4. D. Foramen magnum
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    Answer: D. Foramen magnum

    The medulla becomes the spinal cord at the foramen magnum; herniation of the cerebellar tonsils through it compresses the medulla and causes respiratory arrest. The tentorial notch lies higher, at the level of the midbrain.

19. The adult spinal column normally contains:

    1. A. 7 cervical, 10 thoracic, and 7 lumbar vertebrae
    2. B. 7 cervical, 12 thoracic, and 5 lumbar vertebrae
    3. C. 8 cervical, 12 thoracic, and 4 lumbar vertebrae
    4. D. 5 cervical, 12 thoracic, and 7 lumbar vertebrae
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    Answer: B. 7 cervical, 12 thoracic, and 5 lumbar vertebrae

    There are 7 cervical, 12 thoracic (one per pair of ribs), and 5 lumbar vertebrae, plus the fused sacrum and coccyx. Confusing 8 cervical nerves with 7 cervical vertebrae is a common error.

20. Outside the neck, the part of the spine most often fractured in falls and crashes is the:

    1. A. Thoracolumbar junction, T11-L2
    2. B. Mid-thoracic spine (T4 to T8)
    3. C. Sacrum and the coccyx bone area
    4. D. Upper thoracic spine (T1 to T3)
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    Answer: A. Thoracolumbar junction, T11-L2

    The thoracolumbar junction is where the rigid, rib-splinted thoracic spine meets the mobile lumbar spine, so flexion and axial forces concentrate there, as in falls landing on the feet or buttocks. The mid and upper thoracic spine are protected by the rib cage, and sacral fractures are less common.

21. A man with a C6 spinal cord injury is breathing adequately on scene. Two hours later his breathing becomes shallow and he tires. The most likely reason is:

    1. A. Neurogenic shock slowing his breathing rate
    2. B. Direct C6 paralysis of the diaphragm
    3. C. Cord swelling rising to the C3-C5 level
    4. D. Too much oxygen suppressing his drive
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    Answer: C. Cord swelling rising to the C3-C5 level

    Swelling and bleeding within the injured cord can ascend over hours, affecting the phrenic nerve roots (C3 to C5) and the diaphragm. Combined with intercostal paralysis and fatigue, this can cause sudden respiratory failure, so monitor ETCO2, SpO2, and effort closely and be ready to assist ventilation. Neurogenic shock lowers blood pressure and heart rate but does not depress respiratory drive, a C6 lesion spares the phrenic roots unless the swelling climbs, and supplemental oxygen does not suppress breathing in this patient.

22. Pain and temperature sensation travel to the brain in the:

    1. A. Corticospinal tracts
    2. B. Spinothalamic tracts
    3. C. Dorsal columns
    4. D. Rubrospinal tracts
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    Answer: B. Spinothalamic tracts

    The spinothalamic tracts in the anterolateral cord carry pain and temperature. The dorsal columns carry position sense, vibration, and fine touch, which is why the two can be lost separately in incomplete cord syndromes.

23. Sympathetic outflow to the heart and blood vessels leaves the spinal cord from the:

    1. A. Cervical segments C1 to C8
    2. B. Sacral segments S2 to S4
    3. C. Cranial nerves of the brainstem and medulla
    4. D. Thoracic and upper lumbar segments
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    Answer: D. Thoracic and upper lumbar segments

    Sympathetic fibers exit from about T1 to L2, so a cord injury above that level cuts the brain off from them and can cause neurogenic shock. Sacral segments and cranial nerves carry parasympathetic fibers instead.

24. The thoracic spine is injured less often than the cervical or lumbar spine mainly because it is:

    1. A. Splinted by the ribs and sternum
    2. B. Protected by thicker spinal cord
    3. C. More flexible than the other regions
    4. D. Surrounded by larger vertebral disks
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    Answer: A. Splinted by the ribs and sternum

    The rib cage limits thoracic motion, so fractures there usually require great force. The cervical and lumbar spines are mobile and lack that bracing, which concentrates stress where they meet the rigid segments.

25. A head-injured patient has bilateral pinpoint pupils and a decreased level of consciousness. Besides opioid use, this finding can indicate:

    1. A. Uncal herniation
    2. B. Bleeding in the pons
    3. C. Early hypovolemic shock
    4. D. Oculomotor nerve compression
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    Answer: B. Bleeding in the pons

    Bilateral pinpoint pupils with coma suggest a pontine hemorrhage or injury, which disrupts sympathetic pathways; opioids also cause miosis, so naloxone may be considered if the history fits. Uncal herniation compresses the oculomotor nerve, which dilates the pupil on that side rather than constricting both, and shock does not cause miosis.