All parts of the brain › Functions › Facial expressions

What part of the brain controls facial expressions?

Every facial expression leaves the brain from the facial nucleus in the pons, whose facial nerve works the muscles of the face. Posed expressions start in the face area of the motor cortex on the precentral gyrus; spontaneous emotional ones come from deeper motor systems, with the cingulate gyrus’s face areas, the amygdala and the basal ganglia shaping them. [1][2][3]

The 3D brain needs JavaScript. The list of parts still says what each one does for facial expressions.

Not lit: the facial nerve (not a shape in this model). Lit: whole parts; region borders not drawn.

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; .

Not lit: the facial nerve (cranial nerve VII), which leaves the brainstem where the pons meets the medulla and carries the facial nucleus’s commands to the muscles of facial expression. It is not a separate shape in this atlas (BodyParts3D 4.0), so no marker is placed at a guessed position. [1][4][5] See the facial nerve’s page, lit where it leaves the brain.

The facial motor nucleus is a region on the pons, not a separate shape. The 3D model has no shape for it, so the whole pons is lit; the region’s exact border is not drawn.

The cingulate face areas is a region on the cingulate gyrus, not a separate shape. The 3D model has no shape for it, so the whole cingulate gyrus is lit; the region’s exact border is not drawn.

Facial expressions: 7 parts lit

Precentral gyrus, pons, cingulate gyrus, amygdala, caudate nucleus, putamen and globus pallidus. Tap one to see where it is and what it does.

The parts and their roles

Its face area in the primary motor cortex sends posed, voluntary expressions down the corticobulbar tract to the facial nucleus; in monkeys it and the ventral premotor cortex give that nucleus its heaviest cortical input, mostly to the lower face on the opposite side. [2][6] Where is the motor cortex (precentral gyrus)?
Holds the facial motor nucleus (below): the lower motor neurons whose axons form the motor part of the facial nerve and work every muscle of facial expression, plus the stapedius in the middle ear. [1] Where is the pons?
Holds two face areas of the cingulate motor cortex that project straight to the facial nucleus; in monkeys the front one (M3) reaches the forehead and eyelid muscles on both sides, one possible route by which felt and willed face movements part ways. [6] Where is the cingulate gyrus?
Joins the network that decides to make an expression and monitors it as it is made; in monkeys its lateral basal nucleus projects heavily to the face area of the front cingulate motor cortex (M3), which in turn reaches the facial nucleus. [3][7] Where is the amygdala?
With the putamen it forms the dorsal striatum, the largest part of the basal ganglia, which takes input from many brain areas and sends output only within the basal ganglia; the basal ganglia belong to the extrapyramidal motor system, where spontaneous emotional expressions originate. [8][9][2] Where is the caudate nucleus?
The other half of the dorsal striatum, passing cortical input on to the globus pallidus: one stage of the basal-ganglia loops that adjust movement without driving motor neurons directly. [8][9] Where is the putamen?
The output stage: it takes input from the striatum and sends inhibitory output to motor-related areas; its neurons fire steadily and pause when the striatum signals, releasing their targets (disinhibition). [8] Where is the globus pallidus?

Named areas on the lit gyri

The facial motor nucleus, on the : A cluster of motor neurons in the lower pons (the caudal ventrolateral pontine tegmentum); its axons loop round the abducens nucleus before leaving as the motor part of the facial nerve. Its dorsal neurons serve the upper face, its ventral ones the lower face. [1]
The cingulate face areas, on the : The face representations of the rostral (M3) and caudal (M4) cingulate motor cortex, mapped in rhesus monkeys and called two areas in the midcingulate cortex in a 2014 review; both send fibres to the facial nucleus. [6][3]

How they work together

Two routes reach the face. Posed expressions travel from the primary motor cortex down the pyramidal (corticobulbar) tract; genuine emotional ones come from the extrapyramidal motor system and its subcortical nuclei and are often made without awareness. Infants under two and children born blind show emotional expressions, a sign they are not learned. [2]
The upper face takes orders from both sides of the brain, the lower face mainly from the opposite side: the dorsal facial nucleus (upper face) receives input from both hemispheres, the ventral (lower face) mainly from the other one. So the right hemisphere moves the lower left face. [1][10]
Smiling is mainly the zygomatic major muscle raising the corners of the mouth; in a Duchenne smile the orbicularis oculi also lifts the cheeks and creases the skin around the eyes. Both are muscles of facial expression, worked by the facial nucleus. [11][1]
Because the right hemisphere is more specialised for emotional expression, emotions tend to show more strongly on the left side of the face, especially negative ones; portraits more often show the left side. [2]
Honest limit: these are networks, not single centres. Which cortical area reaches which part of the facial nucleus, and the amygdala’s link to the cingulate face area, were traced in rhesus monkeys; in people the evidence is mostly brain imaging. The facial nucleus is not a separate shape in this atlas, so the whole pons is lit. [6][7][3]

Reading other people’s expressions is a different job: the recognising-faces page lights the fusiform gyrus and the amygdala, whose activity rises sharply when people look at faces. [2] What part of the brain recognises faces?

The emotions page lights the parts that produce the feeling; this page lights the ones that put it on the face. [2] What part of the brain controls emotions?

Sources

Facts describe anatomy and normal function only. A part lit here takes part in facial expressions; 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.