All parts of the brain › Speech

What part of the brain controls speech and understands language?

Mainly a network on the left side of the brain. Broca’s area, on the inferior frontal gyrus, is linked to producing speech; Wernicke’s area, at the back of the superior temporal gyrus next to the auditory cortex, to understanding it; the supramarginal and angular gyri of the parietal lobe join them, and the lowest part of the motor cortex moves the lips, tongue and larynx. Language sits mostly in the left hemisphere in about 95% of right-handed people and about 70% of left-handed people. [1][2][3][4]

Broca’s area, Wernicke’s area and the auditory cortex are regions on these gyri, not separate shapes. The 3D model draws only whole gyri, so the gyrus that holds each area is lit; the area’s exact border is not drawn.

The 3D brain needs JavaScript. The list of parts still says what each one does for speaking and understanding language.

Slice

All 7 parts are lit together. Drag to turn, pinch or scroll to zoom, tap a part on the brain or a name in the list to focus it; .

Speech: 7 parts lit

Inferior frontal gyrus, superior temporal gyrus, supramarginal gyrus, angular gyrus, precentral gyrus, cerebellum and thalamus. Tap one to see where it is and what it does.

The parts and their roles

Holds Broca’s area (pars opercularis and triangularis), linked to producing speech: choosing and ordering words and building grammatical sentences. [2][5] Where is the inferior frontal gyrus?
Holds the auditory cortex, which first receives speech sounds, and at its back Wernicke’s area, linked to understanding spoken words. [6][3] Where is the superior temporal gyrus?
Brodmann area 40 of the parietal lobe; it takes part in language perception and processing, and both sides are active when people make choices about the sounds of words. [7][1] Where is the supramarginal gyrus?
One of the three classical language areas; it links written words seen by the visual cortex to Wernicke’s area, and takes part in reading, writing and the meaning of words. [8][1] Where is the angular gyrus?
The primary motor cortex; its lowest part, at the bottom of the motor body map, drives the face, lips, tongue and larynx that turn a planned word into sound. [9][10] Where is the precentral gyrus?
Times and coordinates articulation, helping string syllables into fast, smooth and rhythmic words and longer sentences. [11] Where is the cerebellum?
Two of its nuclei, the pulvinar and the ventral nucleus, are connected with Broca’s area and engaged in language processing, including linking a meaning to the right word sounds. [1] Where is the thalamus?

Named areas on the lit gyri

Broca’s area, on the : The pars opercularis and pars triangularis at the back of the inferior frontal gyrus (Brodmann areas 44 and 45) of the dominant hemisphere; brain imaging also shows the pars opercularis working while people process complex sentences. [2]
Wernicke’s area, on the : Traditionally Brodmann area 22 at the back of the superior temporal gyrus; it is now often taken to reach into the angular gyrus and nearby parietal cortex, a set of linked areas rather than one sharp region. [3]
Auditory cortex, on the : On the upper surface of the superior temporal gyrus, partly hidden in the lateral sulcus (roughly Brodmann areas 41 and 42), laid out by pitch from low to high; it is the first cortex that hears the speech sounds. [12]

How they work together

Making a sentence runs in three stages: conceptualisation (what to say), formulation (choosing the words and their grammatical forms and sound pattern) and articulation, in which the lungs, larynx, tongue, lips and jaw carry out the planned movements. [11]
The arcuate fasciculus, a curved bundle of white-matter fibres, connects the back of the temporal lobe with the inferior frontal lobe and was long described as the wire between Wernicke’s and Broca’s areas; newer work finds it also reaches the premotor and motor cortex, so that picture is too simple. It is a tract, not a lump of grey matter, and this model does not draw it. [13][3]
The neat two-centre picture of Broca for speaking and Wernicke for understanding is an older simplification: imaging shows the middle and inferior temporal gyri, the supramarginal and angular gyri, the supplementary motor area and the cerebellum also take part, and the left hemisphere usually leads although both sides often work during sentence processing. [1][13]
Honest limit: Broca’s area, Wernicke’s area and the auditory cortex are functional regions on gyri, not shapes of their own on this model, so the whole inferior frontal and superior temporal gyri light; the whole precentral gyrus lights though only its lowest part serves speech; the pulvinar and ventral nuclei light as the whole thalamus; and the model shows both sides even though language usually leans to the left. [2][3][4]

Sources

Facts describe anatomy and normal function only. A part lit here takes part in speaking and understanding language; it does not do it alone, and it does other jobs too. The 3D model is the adult male BodyParts3D brain (credits and licence); on it the brainstem includes the midbrain, pons and medulla, so lighting the brainstem lights all three.