Where is the speech center of the brain located?

Location of Speech Centers in the Brain

The primary speech centers are located in the left hemisphere in most individuals, specifically in Broca's area (posterior inferior frontal gyrus, Brodmann areas 44-45) and Wernicke's area (posterior superior temporal gyrus, Brodmann area 22). 1

Primary Speech Areas

Broca's Area (Motor Speech Production)

• Located in the left inferior frontal gyrus, specifically the pars opercularis (Brodmann area 44) and pars triangularis (Brodmann area 45) 2, 3, 4
• The posterior part (pars opercularis) plays a more prominent role in speech production than the anterior part 5
• Responsible for speech motor planning and articulation 2

Wernicke's Area (Speech Comprehension)

• Located in the posterior part of the left superior temporal gyrus (Brodmann area 22) 3, 4
• Positioned on the most posterior part of the supratemporal plane adjacent to the Sylvian sulcus 2
• Critical for language comprehension and semantic processing 1, 6

Critical White Matter Connections

Arcuate Fasciculus

• The left arcuate fasciculus serves as the primary dorsal language pathway connecting temporal, parietal, and frontal language regions 7
• Damage to this pathway produces repetition deficits with 90% accuracy for naming and 96% accuracy for speech fluency classification 1, 7
• The volume of the left long segment improves prediction of language recovery at six months 7

Additional Language-Critical Regions

Perisylvian Cortex

• The anterior insula (left-lateralized) is activated during both propositional and non-propositional speech 2
• Posterior inferior parietal cortex contributes to propositional speech production 2

Temporal-Parietal Regions

• Posterior middle temporal/fusiform gyrus is critical for naming recovery, particularly in hyperacute stroke 6
• Damage to posterior middle temporal lobe negatively affects aphasia therapy outcomes, especially when proximal to the hippocampus 1, 6

Hemispheric Dominance

Left Hemisphere Dominance

• Language cortex is defined as left hemisphere unless additional clinical data suggest otherwise 1
• Approximately 86% of individuals demonstrate left hemisphere dominance for language 3

Atypical Lateralization

• 14% of patients show atypical language lateralization (right or bilateral) 3
• Bilateral activation occurs in 10% of cases, while right hemisphere dominance occurs in 4% 3

Distributed Language Network

Modern understanding recognizes that speech is not localized to discrete areas but involves distributed bilateral networks 1:

• Bilateral frontal and temporal regions work together for language processing 1
• Frontotemporo-parietal and cingulo-opercular networks interact rather than functioning as isolated centers 1
• The superior temporal gyrus, inferior frontal gyrus, and lingual gyrus show interhemispheric connectivity patterns that correlate with language function 1

Clinical Pitfalls

• Functional localization may differ from anatomical landmarks, particularly in patients with arteriovenous malformations or other lesions where function may reside in non-classic locations 1
• Functional MRI, Wada testing, or brain mapping should be used when precise localization is critical for surgical planning 1
• The right hemisphere can support speech production after left hemisphere damage, particularly involving right cerebellar Crus I and right pars opercularis 5