Vascular supply (Circle of Willis) Practice Questions

Question 1

A 69-year-old man is brought in by his wife with acute onset aphasia for the past 5 hours. The patient's wife says that they were sitting having dinner when suddenly he was not able to speak. They delayed coming to the hospital because he had a similar episode 2 months ago which resolved within an hour. His past medical history is significant for hypercholesterolemia, managed with rosuvastatin, and a myocardial infarction (MI) 2 months ago, status post percutaneous transluminal coronary angioplasty complicated by residual angina. His family history is significant for his father who died of MI at age 60. The patient reports a 15-pack-year smoking history but denies any alcohol or recreational drug use. The vital signs include: temperature 37.0℃ (98.6℉), blood pressure 125/85 mm Hg, pulse 96/min, and respiratory rate 19/min. On physical examination, the patient has expressive aphasia. There is a weakness of the right-sided lower facial muscles. The strength in his upper and lower extremities is 4/5 on the right and 5/5 on the left. There is also a decreased sensation on his right side. A noncontrast computed tomography (CT) scan of the head is unremarkable. CT angiography (CTA) and diffusion-weighted magnetic resonance imaging (MRI) of the brain are acquired, and the findings are shown in the exhibit (see image). Which of the following is the best course of treatment in this patient?

Accepted Answer

Mechanical thrombectomy

Answer

Aspirin

Answer

Mannitol

Answer

IV tPA

Answer

Low molecular weight heparin

Question 2

A 52-year-man is brought to the physician because of a 2-week history of memory loss. Three weeks ago, he had a cardiac arrest that required cardiopulmonary resuscitation and intravenous epinephrine. On mental status examination, he cannot recall objects shown to him 20 minutes earlier but vividly recalls memories from before the incident. The remainder of the examination shows no abnormalities. Which of the following structures of the brain is most likely affected?

Accepted Answer

Pyramidal cells of the hippocampus

Answer

Internal pyramidal layer of the amygdala

Answer

Microglial cells of dorsal midbrain

Answer

Purkinje cells of the cerebellum

Answer

Astroglial cells of the putamen

Question 3

A 59-year-old man is brought to the emergency department by his wife for a 1-hour history of sudden behavior changes. They were having lunch together when, at 1:07 PM, he suddenly dropped his sandwich on the floor. Since then, he has been unable to use his right arm. She also reports that he is slurring his speech and dragging his right foot when he walks. Nothing like this has ever happened before. The vital signs include: pulse 95/min, blood pressure 160/90 mm Hg, and respiratory rate 14/min. The physical exam is notable for an irregularly irregular rhythm on cardiac auscultation. On neurological exam, he has a facial droop on the right half of his face but is able to elevate his eyebrows symmetrically. He has 0/5 strength in his right arm, 2/5 strength in his right leg, and reports numbness throughout the right side of his body. Angiography of the brain will most likely show a lesion in which of the following vessels?

Accepted Answer

Middle cerebral artery

Answer

Posterior cerebral artery

Answer

Internal carotid artery

Answer

Basilar artery

Answer

Anterior cerebral artery

Question 4

A 56-year-old man is brought to the emergency department 25 minutes after the sudden onset of severe pain in the middle of his chest. He describes the pain as tearing in quality; it radiates to his jaw. He has hypertension. He has smoked one pack of cigarettes daily for the 25 years. Current medications include enalapril. His blood pressure is 154/95 mm Hg in his right arm and 181/105 mm Hg in his left arm. A CT scan of the chest is shown. The structure indicated by the arrow is a derivative of which of the following?

Accepted Answer

Truncus arteriosus

Answer

Right horn of sinus venosus

Answer

Primitive atrium

Answer

Right common cardinal vein

Answer

Bulbus cordis

Question 5

A researcher is studying the brains of patients who recently died from stroke-related causes. One specimen has a large thrombus in an area of the brain that is important in relaying many modalities of sensory information from the periphery to the sensory cortex. Which of the following embryologic structures gave rise to the part of the brain in question?

Accepted Answer

Diencephalon

Answer

Metencephalon

Answer

Mesencephalon

Answer

Telencephalon

Answer

Myelencephalon

Question 6

A 28-year-old man is brought to the emergency department by ambulance after developing an altered mental state following blunt trauma to the head. The patient was competing at a local mixed martial arts competition when he was struck in the head and lost consciousness. A few minutes later, upon regaining consciousness, he had a progressive decline in mental status. Past medical history is noncontributory. Upon arrival at the hospital, the temperature is 37.0°C (98.6°F), the blood pressure is 145/89 mm Hg, the pulse is 66/min, the respiratory rate is 14/min, and the oxygen saturation is 99% on room air. He is alert now. A noncontrast CT scan is performed, and the result is provided in the image. Which of the following structures is most likely affected in this patient?

Accepted Answer

Middle Meningeal artery

Answer

Subarachnoid space

Answer

Suprasellar cistern

Answer

Ventricular system

Answer

Bridging veins

Question 7

An 88-year-old woman with no significant medical history is brought to the emergency room by her daughter after a fall, where the woman lightly hit her head against a wall. The patient is lucid and complains of a mild headache. The daughter indicates that her mother did not lose consciousness after the fall. On exam, there are no focal neurological deficits, but you decide to perform a CT scan to be sure there is no intracranial bleeding. The CT scan is within normal limits and head MRI is performed (shown). Which of the following conditions has the most similar risk factor to this patient's condition?

Accepted Answer

Thoracic aortic aneurysm

Answer

Pulmonary embolism

Answer

Raynaud's phenomenon

Answer

Prinzmetal's angina

Answer

Abdominal aortic aneurysm

Question 8

A 44-year-old female is admitted to the neurological service. You examine her chart and note that after admission she was started on nimodipine. Which of the following pathologies would benefit from this pharmacologic therapy?

Accepted Answer

Subarachnoid hemorrhage

Answer

Thromboembolic stroke

Answer

Subdural hematoma

Answer

Epidural hematoma

Answer

Pseudotumor cerebri

Question 9

A 78-year-old right-handed man with hypertension and hyperlipidemia is brought to the emergency department for sudden onset of nausea and vertigo one hour ago. Physical examination shows 5/5 strength in all extremities. Sensation to light touch and pinprick is decreased in the right arm and leg. A CT scan of the brain shows an acute infarction in the distribution of the left posterior cerebral artery. Further evaluation of this patient is most likely to show which of the following findings?

Accepted Answer

Right-sided homonymous hemianopia

Answer

Prosopagnosia

Answer

Left-sided gaze deviation

Answer

Left-sided hemineglect

Answer

Right-sided superior quadrantanopia

Question 10

A 61-year-old man is brought to the emergency department by his son after collapsing to the ground while at home. His son immediately performed cardiopulmonary resuscitation and later the patient underwent successful defibrillation after being evaluated by the emergency medical technician. The patient has a medical history of hypertension, hyperlipidemia, and type II diabetes mellitus. He has smoked one-half pack of cigarettes for approximately 30 years. The patient was admitted to the cardiac intensive care unit, and after a few days developed acute onset right upper extremity weakness. His temperature is 99°F (37.2°C), blood pressure is 145/91 mmHg, pulse is 102/min and irregularly irregular, and respirations are 16/min. On physical examination, the patient is alert and orientated to person, place, and time. His language is fluent and he is able to name, repeat, and read. His strength is 5/5 throughout except in the right hand, wrist, and arm, which is 2/5. Based on this patient's clinical presentation, the affected neuronal fibers decussate at which level of the central nervous system?

Accepted Answer

Caudal medulla

Answer

Pons

Answer

Spinal cord

Answer

Primary motor cortex

Answer

Thalamus

Vascular supply (Circle of Willis)

Study Resources

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Internal carotid artery anatomy

Vertebrobasilar system

Anterior cerebral artery territory

Middle cerebral artery territory

Posterior cerebral artery territory

Communicating arteries

Variations in circle of Willis

Venous drainage of brain

Stroke syndromes by vascular territory

Collateral circulation

Practice Questions

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About Vascular supply (Circle of Willis) for USMLE

Lessons in Vascular supply (Circle of Willis)

Master Vascular supply (Circle of Willis)