The arcuate nucleus is a cluster of neurons in the base of the hypothalamus (the mediobasal hypothalamus), lying against the bottom of the third ventricle and the median eminence. It is one of the brain’s main appetite sensors. [1][2]
The 3D brain needs JavaScript. The text below still says where the arcuate nucleus is and what it does.
Opens cut by a side (sagittal) slice through the hypothalamus, which holds the arcuate nucleus. 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 arcuate nucleus is a small nucleus in the floor of the hypothalamus, in its middle (tuberal) region; BodyParts3D has no shape for it, so the whole hypothalamus is lit and nothing is drawn at a guessed point. Look at the lowest middle part of the lit hypothalamus, just above where the pituitary stalk hangs. [1][2]
Lit here: the hypothalamus, the part that holds the arcuate nucleus — see it on its own page.
It sits in the mediobasal hypothalamus, adjacent to the third ventricle and the median eminence, the spot at the base of the hypothalamus where the pituitary stalk begins. [1]
Of the hypothalamus’s three regions front to back (preoptic/anterior, tuberal, mammillary/posterior), it belongs to the middle, tuberal region, in its medial area, close to the midline. [2]
Its neurons are not sealed off from the blood as most of the brain is: they have their own capillary network next to the median eminence, and a lining of tanycytes forms the barrier there. [1]
What it does
Its inner (medial) neurons use NPY and AgRP and stimulate appetite; its outer (lateral) neurons use POMC and CART and inhibit appetite. Ghrelin from the stomach switches on the first group, leptin from fat tissue the second. [1]
Wikipedia lists its roles as feeding, metabolism, fertility and the control of the heart and blood vessels. [1]
Its tuberoinfundibular dopamine (TIDA) neurons release dopamine at the median eminence into the portal blood of the pituitary, which holds back prolactin release; this is the tuberoinfundibular pathway. [1][3]
Its GHRH neurons help control growth hormone (GH) release, together with somatostatin and NPY. [1][2]
Honest limit: it holds several cell groups side by side (the two appetite groups, dopamine, GHRH and kisspeptin neurons), which no atlas shape here can show apart; the whole hypothalamus stands in for all of them. [1]
It works with the pituitary gland through the median eminence: releasing hormones made in the hypothalamus are carried along axons to the median eminence and on in the portal blood. [2]
Other names
It is also known as the infundibular nucleus, a name that keeps it apart from the arcuate nucleus of the medulla oblongata, a different group of cells. [1]
Size
The model has no shape for the arcuate nucleus 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.