The pons is the middle part of the brainstem: the rounded bulge below the midbrain and above the medulla oblongata, sitting directly in front of the cerebellum at the base of the brain. [1][2]
The 3D brain needs JavaScript. The text below still says where the pons is and what it does.
Slice
Opens cut by a side (sagittal) slice through the pons. Drag to turn, pinch or scroll to zoom, tap any part to name it; .
In humans it lies below (inferior to) the midbrain, above (superior to) the medulla oblongata and in front of (anterior to) the cerebellum. [1]
In cross-section it has a front (ventral) part, the basilar part, with a bulge on each side made by the pontine nuclei, and a back (dorsal) part, the pontine tegmentum. A groove, the medullopontine sulcus, marks its lower edge, and the roots of cranial nerves 6, 7 and 8 emerge along it. [1]
Its back surface forms the upper part of the floor of the fourth ventricle, the fluid-filled space between the pons and medulla in front and the cerebellum behind. [1][3]
With the cerebellum it develops from the metencephalon, part of the hindbrain (rhombencephalon). [1]
What it does
Relays signals from the forebrain to the cerebellum; OpenStax calls the pons the main connection with the cerebellum. [1][4]
Contains nuclei that deal mainly with sleep, breathing, swallowing, bladder control, hearing, balance, taste, eye movement, facial expression, facial sensation and posture. [1]
The pontine respiratory group, one of the three groups of breathing neurons in the brainstem, sits in the pons; its pneumotaxic centre regulates the switch from breathing in to breathing out. [1][5]
With the medulla it regulates the cardiovascular and respiratory systems and their rates. [4]
Connections
Pontine nuclei in its basilar part pass signals from the cerebral cortex to the opposite side of the cerebellum through the thick middle cerebellar peduncles. [1][6]
The corticospinal tract, carrying commands for voluntary movement, runs down through its basilar part on the way to the medulla and spinal cord. [1][7]
Cranial nerve nuclei in it: the trigeminal (V) sensory and motor nuclei, the abducens (VI) and facial (VII) nuclei, and the vestibular and cochlear nuclei of the vestibulocochlear nerve (VIII). [1]
Inside it
Two parts: the basilar part at the front (pontine nuclei and the crossing fibres to the cerebellum) and the tegmentum behind it (cranial nerve nuclei and part of the reticular formation). [1]
Other names
Pons is Latin for bridge. It is also called the pons Varolii (“bridge of Varolius”) after the Italian anatomist and surgeon Costanzo Varolio (1543–1575). [1]
Size
In humans the pons measures about 2.5 cm in length. [1]
On this model the pons measures about 34 mm front to back, 29 mm top to bottom and 42 mm side to side (the box it fits in, not its volume). [8]
Centre of the pons compared with the centre of the cerebellum: 36 mm further forward, 5 mm higher; 37 mm apart in a straight line. [8]
Centre of the pons compared with the centre of the medulla oblongata: 9 mm further forward, 22 mm higher; 24 mm apart in a straight line. [8]
Facts describe anatomy and normal function only. The 3D model is the adult male BodyParts3D brain (credits and licence); real brains vary in size and shape, so its measurements describe one model, not anyone’s brain.