The locus coeruleus is a small nucleus in the pons of the brainstem, at the back of the upper (rostral) pons in the side of the floor of the fourth ventricle. It is the principal site where the brain makes norepinephrine (noradrenaline). [1]
Not a separate shape in this atlas; lit: the part that holds it. Lit: the whole pons. The locus coeruleus is a small nucleus inside the pons, at the back of its upper part beside the floor of the fourth ventricle; it has no shape of its own in the BodyParts3D model, so nothing is drawn at a guessed point. [1][2]
The 3D brain needs JavaScript. The text below still says where the locus coeruleus is and what it does.
Slice
Opens cut by a side (sagittal) slice through the pons, which holds the locus coeruleus. Drag to turn, pinch or scroll to zoom, tap any part to name it; .
Lit here: the pons, the part that holds the locus coeruleus — see it on its own page.
It is located in the posterior area of the rostral pons, in the lateral floor of the fourth ventricle. [1]
The pons is the part of the brainstem between the midbrain above and the medulla oblongata below. [3]
The fourth ventricle, whose floor it lines, is located within the pons or the upper part of the medulla oblongata. [2]
What it does
Through its widespread projections the locus coeruleus–norepinephrine system modulates circuits of the cortex, the deeper forebrain, the cerebellum, the brainstem and the spinal cord. [1]
Functions it influences include arousal and the sleep-wake cycle, attention and memory, cognitive control and flexibility, decision making, emotion, neuroplasticity, and posture and balance. [1]
Its norepinephrine has an excitatory effect on most of the brain, mediating arousal and priming neurons to respond to stimuli; stress activates it and it responds by releasing more norepinephrine. [1]
It is part of the reticular activating system and is almost completely inactive during rapid eye movement (REM) sleep. [1]
Connections
Outputs, using norepinephrine, reach the amygdala and hippocampus, the brainstem and spinal cord, the cerebellum, the cerebral cortex, the hypothalamus, the tectum, the thalamus and the ventral tegmental area. [1]
Inputs include the medial prefrontal cortex, the nucleus paragigantocellularis, the nucleus prepositus (gaze) and the lateral hypothalamus, which releases orexin; the cingulate gyrus, amygdala, cerebellum and raphe nuclei also project to it. [1]
Inside it
Mostly medium-sized neurons; melanin granules inside them give it its blue colour. In adult human males it has about 22,000 to 51,000 pigmented neurons. [1]
Other names
Latin for “blue spot”; also spelled locus caeruleus or locus ceruleus (LC), and also called the blue nucleus or nucleus pigmentosus pontis, the heavily pigmented pontine nucleus. [1]
Size
The model has no shape for the locus coeruleus 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). [4]
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.