The lateral hypothalamus is the outer zone of the hypothalamus, one on each side, running through all three of its regions from front to back. It holds the brain’s orexin (hypocretin) neurons, and its best-known roles are promoting feeding and wakefulness. [1][2][3]
The 3D brain needs JavaScript. The text below still says where the lateral hypothalamus is and what it does.
Opens cut by a side (sagittal) slice through the hypothalamus, which holds the lateral hypothalamus. 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 hypothalamus. The lateral hypothalamus is the outer zone of the hypothalamus, not a separate organ; BodyParts3D has no shape for it, so the whole hypothalamus is lit and nothing is drawn at a guessed point. Look at the outer edge of the lit hypothalamus, away from the midline. [1][2]
Lit here: the hypothalamus, the part that holds the lateral hypothalamus — see it on its own page.
From the midline outwards the hypothalamus has three zones (periventricular, intermediate and lateral); the lateral nucleus appears in the lateral area of each of its three regions, front (anterior), middle (tuberal) and back (posterior). [2]
Its orexin neurons lie mainly in the perifornical area, around the fornix as it passes through the hypothalamus, and in the lateral hypothalamus itself. [3]
What it does
It contains the main orexin-making nucleus of the hypothalamus; the human brain has about 50,000 to 80,000 orexin neurons, which project widely through the nervous system. [1][3]
The orexin system was first thought to drive mainly food intake; the roles most often named for orexin in this region are promoting feeding and arousal, that is, wakefulness. [1][3]
Orexin acts partly by exciting other cell groups that make neurotransmitters, such as the noradrenaline cells of the locus coeruleus. [3]
Its other cited roles: lowering pain perception, regulating body temperature, digestive functions and blood pressure. [1]
Besides orexin, its neurons use other signals, including GABA and melanin-concentrating hormone (MCH). [1]
Connections
Inputs include the medial prefrontal cortex, the central nucleus of the amygdala and the bed nucleus of the stria terminalis. [1]
Its orexin fibres reach the whole of the rest of the hypothalamus, and the brainstem, where orexin tunes automatic (autonomic) body functions. [1][3]
Also called the lateral hypothalamic area (LHA). Orexin was found in 1998 by two groups at once, one of which named it hypocretin, so both names are in use. [1][3]
Size
The model has no shape for the lateral hypothalamus itself, so it is not measured here. The hypothalamus that holds it measures about 18 mm front to back, 20 mm top to bottom and 17 mm side to side on this model (the box it fits in, not its volume). [5]
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.