The limbic system is a set of structures on the inner edge of each cerebral hemisphere, on both sides of the thalamus and just under the cerebral cortex, curving round the top of the brainstem. Its five modelled members are lit together. [1][2]
Not lit: the fornix, the mammillary bodies, the anterior thalamic nuclei, the septum pellucidum and the olfactory bulb, all named as limbic components in the cited source. None is a separate shape in this 3D model (the anterior nuclei are inside the whole thalamus, which this page leaves dark), so no marker is placed at a guessed position. [1][3][4]
The 3D brain needs JavaScript. The text below still says where the limbic system is and what it does.
Slice
All 5 are lit together, on both sides where they are paired; tap a name in the list to focus one. Drag to turn, pinch or scroll to zoom, tap any part to name it; .
Where it is
It is located on both sides of the thalamus, immediately beneath the medial temporal lobe of the cerebrum, mostly in the forebrain. [1]
Its cortical parts form a ring on the inner (medial) face of each hemisphere: the cingulate gyrus above the corpus callosum, continuing round behind it into the parahippocampal gyrus on the underside of the temporal lobe. [5][6]
What it does
It is involved in emotion, behaviour, motivation, long-term memory and the sense of smell. [1]
Honest limit: it is no longer seen as one unit responsible for emotion, and which structures belong to it is debated, so read the lit set as the parts most often named, not a closed list. [1]
Connections
The Papez circuit, proposed in 1937, links several members in a loop: hippocampus → fornix → mammillary bodies → anterior thalamic nuclei → cingulate gyrus → parahippocampal gyrus (entorhinal cortex) → back to the hippocampus. [3]
The fornix, a C-shaped bundle of nerve fibres, is the main output of the hippocampus and runs through the hypothalamus to the mammillary bodies. [7][8]
Other names
Also called the paleomammalian cortex. Limbic comes from the Latin limbus, “edge” or “border”: in 1878 Paul Broca named the ring of cortex on the inner border of each hemisphere the limbic lobe, and Paul MacLean made “limbic system” popular around 1952. [1][5]
Size
On this model the limbic system together fit in a box about 111 mm front to back, 76 mm top to bottom and 75 mm side to side (the box they fit in, not their volume). [4]
Centre of the left amygdala compared with the centre of the left hippocampus: 20 mm further forward; 20 mm apart in a straight line. [4]
Centre of the left cingulate gyrus compared with the centre of the left hippocampus: 32 mm higher, 18 mm closer to the midline; 37 mm apart in a straight line. [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.