The superior olivary complex (the superior olive) is a group of small nuclei in the lower pons, one on each side, closely tied to the trapezoid body. It is the first major site where hearing signals from the left and right ears come together, and it uses the differences between them to work out where a sound comes from. [1][2]
The 3D brain needs JavaScript. The text below still says where the superior olivary complex is and what it does.
Opens cut by a side (sagittal) slice through the pons, which holds the superior olivary complex. 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 pons. The superior olivary complex lies in the lower (caudal) pons, in its back part, the tegmentum: most of its cell groups sit just behind the trapezoid body and some are embedded in it. It is above the medulla, so the medulla is not lit. It has no shape of its own in the BodyParts3D model, so nothing is drawn at a guessed point. [1][2]
Lit here: the pons, the part that holds the superior olivary complex — see it on its own page.
It is a collection of brainstem nuclei in the pons. Most of its cell groups lie just behind (dorsal to) the trapezoid body, a band of crossing hearing fibres in the lower pons, and a few lie inside it. [1][2]
Its three main nuclei are the medial superior olive (MSO), the lateral superior olive (LSO) and the medial nucleus of the trapezoid body (MNTB); smaller periolivary nuclei lie around them. [1]
On the hearing route it is the second step: fibres from the cochlear nuclei, where the medulla meets the pons, run to the superior olive on both sides, and its output climbs the lateral lemniscus to the inferior colliculus of the midbrain. [1][3]
Not to be confused with the inferior olive, lower down in the medulla, which sends climbing fibres to the cerebellum. [4]
What it does
It is the first major place where signals from the two ears converge, so each superior olive receives sound from both ears. [1]
The medial superior olive measures the tiny difference in the time a sound reaches each ear (the interaural time difference), the main cue for where low-pitched sounds come from on the left–right axis. [1][5]
The lateral superior olive compares how loud a sound is at each ear (the interaural level difference), the cue for higher-pitched sounds, which the head shadows; the medial nucleus of the trapezoid body supplies it with the inhibitory signal from the opposite ear. [1][5]
Hearing also runs back down from here: cells around the superior olive send the olivocochlear bundle out to the hair cells of the cochlea, through the vestibulocochlear nerve. [1][6]
Other names
Also the superior olive, the superior olivary nucleus or SOC; “olivary” from oliva, the Latin for olive, shared with the inferior olive below it. [1][4]
Size
The model has no shape for the superior olivary complex itself, so it is not measured here. The pons that holds it measures about 34 mm front to back, 29 mm top to bottom and 42 mm side to side on this model (the box it fits in, not its volume). [7]
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.