A lady presents with vascular injury to the inferior frontal gyrus. Which functional area is likely to be affected?

Explanation

## Correct Answer: A. Motor speech area The inferior frontal gyrus (IFG) is the anatomical location of **Broca's area** (Brodmann area 44, 45, and 47), which is the motor speech area responsible for speech production and articulation. A vascular injury to this region—typically from occlusion of the superior division of the middle cerebral artery (MCA)—results in **Broca's aphasia** (expressive or non-fluent aphasia). Patients present with effortful, halting speech with agrammatism and anomia, though comprehension remains relatively preserved. The inferior frontal gyrus is located in the dominant hemisphere (left in ~95% of right-handed individuals and ~70% of left-handed individuals). This is a high-yield anatomical correlation tested repeatedly in NEET PG because it directly links vascular territory (MCA superior division) to a specific functional deficit. The motor speech area controls the motor planning and execution of speech through connections with the motor cortex and brainstem nuclei controlling speech musculature. ## Why the other options are wrong **B. Auditory area** — The primary auditory cortex (Brodmann area 41, 42) is located in the **superior temporal gyrus** (Heschl's gyrus), not the inferior frontal gyrus. Injury here causes auditory processing deficits, not speech production problems. This is a common anatomical trap—students confuse temporal lobe structures with frontal lobe speech areas. **C. Visual area** — The primary visual cortex (Brodmann area 17) is located in the **occipital lobe** along the calcarine fissure, far removed from the inferior frontal gyrus. Vascular injury here causes homonymous hemianopia or cortical blindness, not speech deficits. This is an obvious distractor but tests whether students know basic cortical localization. **D. Wernicke's area** — Wernicke's area (Brodmann area 22) is located in the **superior temporal gyrus** (posterior-superior temporal region), not the inferior frontal gyrus. Injury causes receptive (fluent) aphasia with preserved articulation but impaired comprehension—the opposite clinical picture of Broca's aphasia. NBE pairs these two aphasias to test whether students can distinguish their anatomical locations. ## High-Yield Facts - **Broca's area** = inferior frontal gyrus (Brodmann 44, 45, 47) → motor/expressive speech - **Broca's aphasia** = non-fluent, effortful speech with agrammatism; comprehension relatively preserved - **MCA superior division** occlusion classically causes Broca's aphasia via IFG infarction - **Wernicke's area** = superior temporal gyrus (Brodmann 22) → receptive speech; injury causes fluent but incomprehensible speech - **Dominant hemisphere** = left in ~95% right-handed, ~70% left-handed individuals; speech areas always ipsilateral to dominance ## Mnemonics **BROCA = Broken speech (Broca's area)** **B**roca = **B**roken, effortful speech | **I**nferior **F**rontal **G**yrus = **I**nferior **F**rontal location. Patients struggle to produce speech (expressive deficit) but understand what you say. **WERNICKE = Words make no sense (Wernicke's area)** **W**ernicke = **W**ord salad (fluent but nonsensical) | **S**uperior **T**emporal **G**yrus = **S**uperior **T**emporal location. Patients speak fluently but don't understand and produce gibberish. ## NBE Trap NBE pairs Broca's and Wernicke's areas in the same question to test whether students can distinguish **location** (inferior frontal vs. superior temporal) and **clinical presentation** (non-fluent vs. fluent aphasia). Students who memorize "speech area = Broca" without anatomical precision often confuse the two. ## Clinical Pearl In Indian stroke units, a patient presenting with acute left MCA superior division stroke will show **right hemiparesis + Broca's aphasia** (non-fluent speech with intact comprehension). This combination—motor deficit + expressive speech loss—is pathognomonic for inferior frontal gyrus involvement and helps clinicians rapidly localize the lesion for thrombolytic eligibility assessment. _Reference: Guyton & Hall Textbook of Medical Physiology (Ch. 57: Cerebral Cortex, Intellectual Functions of the Brain); Harrison's Principles of Internal Medicine (Ch. 27: Aphasia and Other Focal Cerebral Disorders)_