Blood Supply of the Brain Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Blood Supply of the Brain. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Blood Supply of the Brain Indian Medical PG Question 1: Berry aneurysm most commonly occurs due to?
- A. Muscle and adventitial layer defect
- B. Medial layer and internal elastic lamina defect (Correct Answer)
- C. Endothelial injury of vessel due to HTN
- D. Adventitia defect
Blood Supply of the Brain Explanation: ***Medial layer and internal elastic lamina defect***
- **Berry aneurysms** are most commonly saccular dilatations that occur at arterial bifurcations in the **Circle of Willis** [1].
- These aneurysms result from a congenital or acquired weakness in the **tunica media** and the **internal elastic lamina** at these bifurcation points, making the vessel wall susceptible to high pressures [1].
*Muscle and adventitial layer defect*
- Defects primarily in the **muscle layer** (media) and **adventitia** are less commonly the primary cause of berry aneurysms.
- While all layers contribute to vessel integrity, the specific absence in the medial and internal elastic lamina is key for berry aneurysms [1].
*Endothelial injury of vessel due to HTN*
- While hypertension is a significant **risk factor** for aneurysm formation and rupture, it primarily exacerbates existing structural weaknesses rather than being the direct cause of the initial structural defect.
- **Endothelial injury alone** is not the primary anatomical defect responsible for generating berry aneurysms; it contributes to atherosclerosis, which can lead to other types of aneurysms.
*Adventitia defect*
- A defect solely in the **adventitia** is not the primary predisposing factor for berry aneurysms.
- The adventitia provides external support, but the integrity of the media and internal elastic lamina is crucial for maintaining the vessel's structural strength against intraluminal pressure [1].
**References:**
[1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1272-1273.
Blood Supply of the Brain Indian Medical PG Question 2: Not seen in case of hemorrhage in MCA territory is:
- A. Contralateral hemiplegia
- B. Aphasia
- C. Urinary incontinence (Correct Answer)
- D. Dysarthria
Blood Supply of the Brain Explanation: ***Urinary incontinence***
- Urinary incontinence is typically associated with **anterior cerebral artery (ACA)** territory lesions, which affect the **paracentral lobule** responsible for bladder control.
- MCA territory hemorrhage primarily impacts motor, sensory, speech, and attentional functions, not direct bladder control.
*Contralateral hemiplegia*
- Hemorrhage in the MCA territory commonly affects the **motor cortex** and its descending tracts, leading to **weakness or paralysis** on the opposite side of the body [1].
- This is a very common and expected symptom in MCA strokes.
*Aphasia*
- If the dominant hemisphere (usually left) is affected,MCA territory hemorrhage often involves **Broca's and Wernicke's areas**, leading to various forms of **aphasia** (expressive or receptive speech difficulties) [1].
- This is a hallmark symptom of dominant MCA strokes.
*Dysarthria*
- Dysarthria, or difficulty with articulation of speech, can result from MCA territory hemorrhage affecting the motor pathways that control the **muscles of speech** [1].
- It often co-occurs with hemiplegia and other motor deficits.
Blood Supply of the Brain Indian Medical PG Question 3: Thrombosis of which cerebral vessels leads to hemiplegia?
- A. Anterior cerebral
- B. Middle cerebral (Correct Answer)
- C. Posterior cerebral
- D. Not applicable
Blood Supply of the Brain Explanation: Everything below the bolded header ***Middle cerebral*** relates to the vessel responsible for hemiplegia.
***Middle cerebral***
- Thrombosis of the **middle cerebral artery (MCA)** commonly leads to contralateral **hemiplegia** (weakness on one side of the body), particularly affecting the face and arm more than the leg [1].
- The MCA supplies blood to the primary motor cortex areas responsible for **volitional movement** of these body parts [1].
*Anterior cerebral*
- Thrombosis of the **anterior cerebral artery (ACA)** typically causes contralateral weakness, but it predominantly affects the **leg** more than the arm or face [1].
- The ACA supplies the motor cortex areas controlling the **lower limbs** [1].
*Posterior cerebral*
- Thrombosis of the **posterior cerebral artery (PCA)** primarily causes **visual field defects** (e.g., contralateral homonymous hemianopsia) due to involvement of the occipital lobe [1].
- While it can cause other neurological deficits, **hemiplegia** is not its most common or prominent presentation [1].
*Not applicable*
- This option is incorrect because specific cerebral vessel thrombosis clearly leads to distinct neurological deficits, including **hemiplegia**, depending on the affected artery and its vascular territory [1].
Blood Supply of the Brain Indian Medical PG Question 4: Wallenberg syndrome involves which artery?
- A. Subclavian artery
- B. Posterior cerebral artery
- C. Posterior inferior cerebellar artery (Correct Answer)
- D. Anterior inferior cerebellar artery
Blood Supply of the Brain Explanation: ***Posterior inferior cerebellar artery***
- **Wallenberg syndrome**, also known as **lateral medullary syndrome**, is most commonly caused by an infarction in the territory supplied by the **posterior inferior cerebellar artery (PICA)**.
- The PICA supplies the **lateral medulla**, which contains several crucial nuclei and tracts, including the nucleus ambiguus, trigeminal nucleus, vestibular nuclei, and spinothalamic tract, leading to the characteristic clinical presentation of Wallenberg syndrome.
*Subclavian artery*
- The **subclavian artery** is a large artery in the upper thorax that supplies blood to the upper limbs, head, and neck.
- While it can be involved in conditions like **subclavian steal syndrome**, it does not directly supply the lateral medulla responsible for Wallenberg syndrome.
*Posterior cerebral artery*
- The **posterior cerebral artery** primarily supplies the occipital lobe, temporal lobe, and parts of the thalamus and midbrain.
- Infarction in the PCA territory typically leads to symptoms like **hemianopia**, visual field defects, and memory deficits, not the constellation of symptoms seen in Wallenberg syndrome.
*Anterior inferior cerebellar artery*
- The **anterior inferior cerebellar artery (AICA)** supplies the anterior and lateral parts of the cerebellum and the pontomedullary junction, leading to **lateral pontine syndrome** when infarcted.
- Symptoms of AICA infarction include ipsilateral facial paralysis, hearing loss, and cerebellar ataxia, which are distinct from Wallenberg syndrome.
Blood Supply of the Brain Indian Medical PG Question 5: Ophthalmic artery is a branch of:
- A. Cavernous part of ICA
- B. Cerebral part of ICA (Correct Answer)
- C. MCA
- D. Facial artery
Blood Supply of the Brain Explanation: ***Cerebral part of ICA***
- The **ophthalmic artery** is typically the first major branch off the **internal carotid artery (ICA)** once it exits the cavernous sinus and enters the cranial cavity.
- This segment of the ICA is also known as the supraclinoid or **cerebral part**, underscoring its proximity to the brain.
*Cavernous part of ICA*
- The **cavernous part of the ICA** is located within the cavernous sinus and typically gives off smaller branches such as the **meningohypophyseal trunk** and the **inferolateral trunk**, which supply structures within and around the sinus.
- The ophthalmic artery emerges after the ICA exits the cavernous sinus, not from within it.
*MCA*
- The **middle cerebral artery (MCA)** is a major terminal branch of the internal carotid artery, supplying large parts of the cerebrum.
- It does not give rise to the ophthalmic artery, which branches off the ICA before the ICA bifurcates into the MCA and anterior cerebral artery.
*Facial artery*
- The **facial artery** is a branch of the **external carotid artery**, supplying structures of the face.
- The ophthalmic artery is a primary supply to the orbit and is derived from the internal carotid artery, a completely separate vascular system.
Blood Supply of the Brain Indian Medical PG Question 6: Superficial middle cerebral vein drains into -
- A. Internal cerebral vein
- B. Cavernous sinus (Correct Answer)
- C. Great cerebral vein of Galen
- D. Straight sinus
Blood Supply of the Brain Explanation: **Cavernous sinus**
- The **superficial middle cerebral vein** runs along the **lateral sulcus** and is a major drainage pathway, typically emptying into the **cavernous sinus**.
- Its drainage into the **cavernous sinus** then allows blood to eventually reach the superior and inferior petrosal sinuses [1].
*Internal cerebral vein*
- This vein is part of the **deep venous system** of the brain [1] and primarily drains structures like the **basal ganglia** and **thalamus**.
- It does not receive direct drainage from the **superficial middle cerebral vein**.
*Great cerebral vein of Galen*
- The **great cerebral vein of Galen** is formed by the union of the **internal cerebral veins** and is a major collector of **deep venous blood**.
- It drains into the **straight sinus** and is not the primary drainage site for the superficial middle cerebral vein.
*Straight sinus*
- The **straight sinus** is a large dural venous sinus that receives blood from the **great cerebral vein of Galen** and the **inferior sagittal sinus**.
- It primarily drains deeper structures of the brain and does not directly receive the **superficial middle cerebral vein** [1].
Blood Supply of the Brain Indian Medical PG Question 7: Which artery supplies blood to the primary visual cortex?
- A. Anterior cerebral
- B. Basilar artery
- C. Posterior cerebral (Correct Answer)
- D. Middle cerebral
Blood Supply of the Brain Explanation: **Posterior cerebral**
- The **posterior cerebral artery (PCA)** is the primary blood supply to the **occipital lobe**, where the **primary visual cortex** (Brodmann areas 17, 18, 19) is located. [1]
- A stroke affecting the PCA can lead to **contralateral homonymous hemianopsia** with macular sparing. [1]
*Anterior cerebral*
- The **anterior cerebral artery (ACA)** supplies the **medial frontal and parietal lobes**. [1]
- Occlusion typically causes **contralateral leg weakness** and sensory loss, and behavioral changes.
*Basilar artery*
- The **basilar artery** supplies the **brainstem** and **cerebellum**, and branches into the posterior cerebral arteries.
- While it's part of the posterior circulation, it doesn't directly supply the primary visual cortex; its occlusion leads to severe brainstem syndromes like **locked-in syndrome**.
*Middle cerebral*
- The **middle cerebral artery (MCA)** supplies the **lateral surface of the frontal, parietal, and temporal lobes**. [1]
- MCA strokes typically result in **contra-lateral hemiparesis**, sensory loss, aphasia (if dominant hemisphere), and hemineglect (if non-dominant hemisphere).
Blood Supply of the Brain Indian Medical PG Question 8: Cerebral blood flow is regulated by all, EXCEPT:
- A. Intracranial pressure
- B. Cerebral metabolic rate
- C. Potassium ions (Correct Answer)
- D. Arterial PCO2
Blood Supply of the Brain Explanation: ***Potassium ions***
- While potassium ions play a crucial role in neuronal excitability and membrane potential, they are **not a primary direct regulator** of cerebral blood flow (CBF) in the same way as other factors listed.
- Changes in extracellular potassium can affect vascular smooth muscle, but their direct impact on CBF auto-regulation is less pronounced compared to metabolic or pressure-related factors.
*Intracranial pressure*
- **Increased intracranial pressure (ICP)** can significantly decrease cerebral blood flow due to the **Monro-Kellie doctrine**, which states that an increase in ICP reduces the cerebral perfusion pressure (CPP).
- A sustained and significant elevation in ICP can lead to **cerebral ischemia** as it opposes the arterial pressure driving blood into the brain.
*Arterial PCO2*
- **Arterial PCO2** is a potent regulator of cerebral blood flow, with **hypercapnia (high PCO2)** causing **vasodilation** and increased CBF.
- Conversely, **hypocapnia (low PCO2)** leads to **vasoconstriction** and decreased CBF, which is a key mechanism in the management of cerebral edema.
*Cerebral metabolic rate*
- **Cerebral metabolic rate (CMR)** is directly coupled to cerebral blood flow, meaning that regions of the brain with higher metabolic activity receive increased blood flow.
- This **neurovascular coupling** ensures adequate supply of oxygen and nutrients to meet the brain's metabolic demands.
Blood Supply of the Brain Indian Medical PG Question 9: Which artery is involved in Lateral medullary syndrome?
- A. Posterior inferior cerebellar artery (Correct Answer)
- B. Vertebral artery
- C. Anterior inferior cerebellar artery
- D. Superior cerebellar artery
Blood Supply of the Brain Explanation: ***Posterior inferior cerebellar artery (PICA)***
- **Lateral medullary syndrome**, also known as **Wallenberg syndrome**, is most commonly caused by ischemia due to occlusion of the **posterior inferior cerebellar artery (PICA)**.
- PICA supplies the **lateral medulla**, which includes critical structures like the **nucleus ambiguus**, spinal trigeminal nucleus, vestibular nuclei, and spinothalamic tract, leading to the characteristic constellation of symptoms.
*Vertebral artery*
- While the **vertebral artery** is the parent vessel of PICA, direct occlusion of the vertebral artery itself leads to a wider range of neurological deficits, often involving more extensive parts of the brainstem and cerebellum, not isolated to the lateral medulla in the classic Wallenberg presentation.
- Complete occlusion of the vertebral artery can cause **PICA territory infarction** as well as other territories, but isolated PICA syndrome implies more distal occlusion.
*Anterior inferior cerebellar artery (AICA)*
- Occlusion of the **AICA** typically leads to **lateral pontine syndrome**, affecting structures within the pons rather than the medulla.
- Symptoms of AICA syndrome include **ipsilateral hearing loss**, facial weakness, and cerebellar ataxia, distinct from the medullary symptoms.
*Superior cerebellar artery (SCA)*
- Occlusion of the **SCA** causes **superior cerebellar syndrome**, primarily affecting the cerebellum and upper brainstem.
- This results in severe **ipsilateral cerebellar ataxia**, dysmetria, and dysdiadochokinesia, with minimal or no involvement of the medulla.
Blood Supply of the Brain Indian Medical PG Question 10: All of the following take part in the blood supply of the optic chiasm except:
- A. Anterior cerebral artery
- B. Middle cerebral artery (Correct Answer)
- C. Anterior communicating artery
- D. Internal carotid artery
Blood Supply of the Brain Explanation: ***Middle cerebral artery***
- The **middle cerebral artery (MCA)** primarily supplies the lateral surface of the cerebral hemispheres, including portions of the frontal, parietal, and temporal lobes, but does not typically contribute to the direct blood supply of the **optic chiasm** [2].
- Its branches are more directed towards the **sylvian fissure** and cortical structures, rather than the deep midline structures like the optic chiasm [2].
*Anterior cerebral artery*
- The **anterior cerebral artery (ACA)**, through its branches, including the **anterior communicating artery**, helps supply the anterior part of the optic chiasm [3].
- It forms part of the **Circle of Willis**, from which small perforating arteries can arise to supply deep brain structures [1].
*Anterior communicating artery*
- The **anterior communicating artery (AComA)** connects the two anterior cerebral arteries and gives rise to small branches that directly contribute to the vascular supply of the **optic chiasm** [3].
- These branches are crucial for maintaining blood flow to this critical visual pathway structure.
*Internal carotid artery*
- The **internal carotid artery (ICA)** gives rise to the **ophthalmic artery** and the **anterior cerebral artery**, both of which contribute to the blood supply of the optic chiasm [3].
- Perforating branches from the ICA itself, particularly its terminal portion before bifurcating, can also directly supply the optic chiasm [3].
More Blood Supply of the Brain Indian Medical PG questions available in the OnCourse app. Practice MCQs, flashcards, and get detailed explanations.
A