All parts of the brain › Functions › Swallowing

What part of the brain controls swallowing?

A swallowing centre in the brainstem’s medulla oblongata and pons runs each swallow once it starts: generator neurons in the solitary nucleus time the sequence and the nucleus ambiguus drives the throat and voice-box muscles. The cortex (precentral gyrus, insula, cingulate gyrus) starts the voluntary mouth phase, and the cerebellum fine-tunes the movement. [1][2][3][4]

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

Not lit: the cranial nerves IX, X and XII (not a shape in this model). Lit: whole parts; region borders not drawn.

Slice

All 6 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 cranial nerves IX, X and XII (the glossopharyngeal, vagus and hypoglossal nerves) that carry swallowing: IX senses the back of the tongue and throat where the reflex starts, IX and X work the throat and voice box through the pharyngeal plexus, and XII moves the tongue. Each is not a separate shape in this atlas (BodyParts3D 4.0), so no marker is placed at a guessed position; each nerve’s page lights the medulla it leaves from. [1][5] See the glossopharyngeal nerve (IX), the vagus nerve (X), the hypoglossal nerve (XII).

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

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

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

Swallowing: 6 parts lit

Medulla oblongata, pons, precentral gyrus, insula, cingulate gyrus and cerebellum. Tap one to see where it is and what it does.

The parts and their roles

Holds the swallowing central pattern generator: generator neurons in the dorsal medulla, inside the solitary nucleus, trigger, shape and time the sequence, and switching neurons in the ventrolateral medulla hand the drive to the motor neurons of the throat, voice box and tongue. [2] Where is the medulla oblongata?
Wikipedia’s Swallowing article places the swallowing centre on the medulla and the pons together; the trigeminal nerve, which leaves the pons, works the chewing muscles, the mylohyoid that lifts the tongue and the tensor that tightens the soft palate. [1][6] Where is the pons?
Its motor cortex is the most consistent cortical finding: a 2009 analysis pooling twelve brain-imaging studies found the sensorimotor cortex active on both sides, and the precentral gyrus on both sides more for saliva than for water. Its corticobulbar fibres reach the swallowing nuclei of the brainstem directly. [3][7] Where is the motor cortex (precentral gyrus)?
In the same analysis a cluster in the right front (anterior) insula was active when people swallowed water, and more for water than for saliva. [3] Where is the insula?
Active on both sides when people swallow saliva, its front (anterior) part more than for water, together with the supplementary motor area; the authors link these premotor regions to starting and controlling a movement. [3] Where is the cingulate gyrus?
Brain scans show it more active during swallowing; it takes input from motor and sensory cortex and fine-tunes it into coordinated output, and single magnetic pulses over it (TMS) evoke muscle responses in the throat. [4] Where is the cerebellum?

Named areas on the lit gyri

The solitary nucleus, on the : A column of grey matter in the medulla that receives taste and gut sensation through the facial, glossopharyngeal and vagus nerves. The swallowing generator neurons sit inside it, so the relay that feels the food also times the swallow. [8][2]
The nucleus ambiguus, on the : A group of large motor neurons deep in the upper medulla, just behind the inferior olive; through the vagus and glossopharyngeal nerves it works the muscles of the soft palate, throat (pharynx), voice box (larynx) and upper oesophagus. [9]
The hypoglossal nucleus, on the : Near the midline of the medulla, under the floor of the fourth ventricle; its fibres form the hypoglossal nerve to the tongue muscles that shape a trough at the back of the tongue and push the food back. [10][1]

How they work together

A swallow runs in three phases: the oral phase (chewing and shaping the food into a bolus), which is voluntary and steered from the cerebral cortex; the pharyngeal phase, a reflex set off by touch receptors at the back of the mouth and coordinated by the swallowing centre; and the oesophageal phase, involuntary waves that carry the bolus to the stomach at 3–5 cm/s. [1]
Once the throat phase starts it is hard to stop: the soft palate seals off the nose, the vocal folds close, the larynx rises under the tongue and the epiglottis tips down, while chewing, breathing and coughing are held off. In healthy adults the bolus crosses the throat at about 30–40 cm/s, and gravity matters so little that people can swallow standing on their heads. [1]
The cortex reaches the brainstem through the corticobulbar tract, which serves most of these muscles from both sides of the brain; it reaches the nuclei of nerves V, VII, IX and XII directly and the motor region of X in the nucleus ambiguus. [7]
Honest limit: the swallowing pattern generator is a network of neurons in the brainstem, not a separate shape in this atlas, so the whole medulla oblongata and pons are lit; its layout was mapped mainly with microelectrode recordings in animals. The cortical parts come from brain scans of healthy people pooled across studies (twelve in the 2009 analysis), which show where activity rises, not what each area does on its own. [2][3]

Swallowing and breathing share the throat: for the brief moment of each swallow the swallowing centre holds off the breathing centre of the medulla (deglutition apnoea), and most swallows fall while breathing out. [1] What part of the brain controls breathing?

The soft-palate, throat and voice-box muscles the nucleus ambiguus works serve speech as well as swallowing. [9] What part of the brain controls speech and understands language?

Sources

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