The inferior olive (inferior olivary nucleus) is a folded band of grey matter inside the medulla oblongata, under the olive: the oval bulge, about 1.25 cm long, beside each pyramid on the front of the medulla. It is the source of the climbing fibres to the cerebellum. [1][2]
The 3D brain needs JavaScript. The text below still says where the inferior olive is and what it does.
Opens cut by a side (sagittal) slice through the medulla oblongata, which holds the inferior olive. Drag to turn, pinch or scroll to zoom, tap any part to name it; .
Not a separate shape in this atlas; lit: the part that holds it. Lit: the whole medulla oblongata. The inferior olive lies inside the medulla oblongata, under the olive on its front surface: behind the pyramid and in front of the inferior cerebellar peduncle. It has no shape of its own in the BodyParts3D model, so nothing is drawn at a guessed point. [1][2]
Lit here: the medulla oblongata, the part that holds the inferior olive — see it on its own page.
The olives, or olivary bodies, are a pair of oval bulges on the front of the medulla, each beside a pyramid and separated from it by the antero-lateral sulcus and the rootlets of the hypoglossal nerve; each is about 1.25 cm long in humans. [2]
The olives are swellings caused by the largest nuclei under them, the inferior olivary nuclei; inside, each lies behind the pyramid and in front of the inferior cerebellar peduncle, as a folded, layered band. [3][1]
It has three parts: the large folded principal olivary nucleus and two smaller curved sheets, the medial and dorsal accessory olivary nuclei. [1]
Not to be confused with the superior olivary nucleus, higher up and counted as part of the pons, which is a relay for hearing. [2]
What it does
Its neurons are the main source of climbing fibres: their axons leave it on the inner side, cross the midline and rise into the cerebellum through the inferior cerebellar peduncle. [1][4]
Each climbing fibre ends on a Purkinje cell of the cerebellum; an adult Purkinje cell keeps exactly one, the extra ones of early life being pruned after birth. [1]
It relays signals from the spinal cord to the cerebellum for motor coordination and learning, such as perfecting a jump shot; recent work suggests the timing of its signals is what matters most. [1]
Connections
Inputs: the principal nucleus from the red nucleus and the cerebral cortex, the medial accessory nucleus from the tectum and pretectum, the dorsal accessory nucleus from the spinal cord and the dorsal column nuclei. In humans most of the red nucleus’s output runs to the inferior olive of the same side. [1][5]
Outputs: the principal nucleus reaches the intermediate cerebellum and the cerebellar hemispheres; the accessory nuclei reach the vermis, and the medial one also the flocculus. [1]
Other names
Also the inferior olivary nucleus or complex (ION); oliva is the Latin for olive. [1][2]
Size
The model has no shape for the inferior olive itself, so it is not measured here. The medulla oblongata that holds it measures about 33 mm front to back, 41 mm top to bottom and 27 mm side to side on this model (the box it fits in, not its volume). [6]
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.