Broca area

ANATOMY: Located in the pars opercularis (BA 44) and pars triangularis (BA 45) of the inferior frontal gyrus, in the dominant hemisphere (left in ~95% of right-handers and ~60-70% of left-handers). Blood supply: superior division of the middle cerebral artery (MCA). It connects to Wernicke area (posterior superior temporal gyrus, BA 22) via the arcuate fasciculus.

FUNCTION: Motor planning and production of speech (and grammar/syntax processing). It sends output to the adjacent primary motor cortex (face/mouth region) to execute articulation.

BROCA (EXPRESSIVE, NONFLUENT) APHASIA: - Speech: nonfluent, effortful, halting, telegraphic speech with agrammatism (content words preserved, function words omitted), e.g., "Walk... dog... park." - Comprehension: relatively intact. - Repetition: impaired. - Naming: impaired. - Insight: patients are usually aware of the deficit and frustrated, so depression is common. - Associated findings: right facial droop and right arm weakness (adjacent motor cortex), and sometimes apraxia of speech. Usually no visual field cut. - Etiology: most commonly ischemic stroke of the superior division of the left MCA. Others include tumor, hemorrhage, trauma, and neurodegenerative disease such as primary progressive aphasia (nonfluent/agrammatic variant, frontotemporal dementia spectrum).

COMPARISON (high-yield): - Wernicke aphasia: fluent but nonsensical speech (word salad), impaired comprehension, impaired repetition, and unawareness of the deficit. Lesion in the superior temporal gyrus (inferior division of MCA). - Conduction aphasia: fluent speech, intact comprehension, impaired repetition. Lesion in the arcuate fasciculus. - Global aphasia: Broca plus Wernicke areas affected (large MCA stroke). Both fluency and comprehension impaired. - Transcortical motor aphasia: like Broca but with intact repetition (watershed ACA-MCA infarct). - Transcortical sensory aphasia: like Wernicke but with intact repetition. - Mixed transcortical aphasia: impaired fluency and comprehension with intact repetition (watershed). - Anomic aphasia: isolated naming difficulty.

BOARD PEARLS: "Broca = Broken boca (mouth)": can't speak but understands. Fluency and repetition are impaired, while comprehension is intact. Look for a right-sided face/arm weakness plus nonfluent speech in a stroke vignette. Evaluation is by urgent noncontrast head CT (rule out hemorrhage), then tPA/thrombectomy if eligible. Management includes speech-language therapy.