Olive
Oliva
An oval swelling on the front of the medulla oblongata, beside the pyramid, produced by the inferior olivary nucleus beneath it.
At a glance
- English
- Olive
- Latin (TA2)
- Oliva
- System
- Brain and spinal cord
- Region
- Head
- Side
- Paired, left and right
About the olive
The olive, or olivary body, is a smooth oval bulge on each side of the upper medulla oblongata. It lies on the anterolateral surface, just lateral to the pyramid, and is about one and a quarter centimetres long. The bulge is made by the inferior olivary nucleus, a large folded sheet of grey matter just beneath the surface.
Its borders are well marked. Medially the anterolateral sulcus separates it from the pyramid, and the rootlets of the hypoglossal nerve emerge in this groove. Behind it lies the posterolateral sulcus, from which the glossopharyngeal, vagus and accessory rootlets emerge, with the ventral spinocerebellar tract between the two. Above, a small depression separates the olive from the lower border of the pons; the facial and vestibulocochlear nerves attach near this point. External arcuate fibres sweep over the lower ends of the olive and pyramid towards the inferior cerebellar peduncle.
Inside, the inferior olivary complex has three parts. The principal nucleus is a crumpled bag of grey matter like a purse, open medially at its hilum, from which olivocerebellar fibres stream out. The medial accessory nucleus lies between the principal nucleus and the pyramid, and the smaller dorsal accessory nucleus lies behind it. Smaller groups such as the dorsal cap are also described. Olivary fibres cross the midline and enter the opposite cerebellum as climbing fibres, which play a central part in timing movements and in motor learning. The superior olivary nucleus, despite the name, lies in the pons and belongs to the auditory pathway, helping to locate sounds.
Lesions involving the dentate nucleus, red nucleus and inferior olive can enlarge the olive, a change seen on MRI and linked with rhythmic palatal tremor.
Function and supply
- Function
- Marks the position of the inferior olivary nucleus, whose climbing fibres to the opposite cerebellum help coordinate and learn movements.
- Blood supply
- Branches of the vertebral artery, the anterior spinal artery and the posterior inferior cerebellar artery.
Anthromica
See the olive where it really sits, with every layer of the body around it.
- Every layer, one body. Peel from muscle to bone, nerve, vessel and organ, and turn it any way.
- English and Latin. Every structure named the way your exam names it.
- Quiz until it sticks. Short drills on the structures you keep missing.
Free to start. No card.
