The insula is cortex folded deep inside the lateral (Sylvian) sulcus of each hemisphere, the fissure that separates the temporal lobe from the frontal and parietal lobes. It is hidden: the frontal, parietal and temporal lobes fold over it like a lid. [1][2]
The 3D brain needs JavaScript. The text below still says where the insula is and what it does.
Slice
Opens cut by a front (coronal) slice through the insula. Drag to turn, pinch or scroll to zoom, tap any part to name it; .
Deep within the lateral sulcus, the most prominent groove of each hemisphere, which separates the frontal and parietal lobes above from the temporal lobe below. [2]
Not visible on the surface of an intact brain: the cortex covering it toward the outside is the operculum (“lid”), formed by parts of the frontal, temporal and parietal lobes. [1]
Its edge is the circular sulcus (sulcus of Reil), a semicircular groove that separates it from the opercular gyri in front, above and behind. [1]
Paired: one insula in each hemisphere. Some authorities count it as a separate lobe, others as part of the temporal lobe, and it is sometimes grouped into the limbic lobe. [1]
What it does
Interoception: it handles sensations from inside the body, such as warmth or coolness on the skin, a stretched stomach or a full bladder, and the right front insula is linked with the ability to feel one’s own heartbeat. [1]
Taste: the anterior insula is part of the primary gustatory cortex; in rhesus monkeys its neurons also respond to the texture and temperature of food in the mouth. [1]
The cortex that processes vestibular (balance) sensations extends into the insula. [1]
Body regulation: it takes part in autonomic control through the sympathetic and parasympathetic systems, and it has been described as a “central command” centre that raises heart rate and blood pressure at the start of exercise. [1]
Speech: the anterior insula is part of the network for the motor control of speech, coordinating the articulation movements. [1]
It is also linked with emotion, empathy, judging how strong a pain is, and the sense of owning one’s body. [1]
Connections
Front part: receives a direct projection from the ventral medial nucleus of the thalamus and a particularly large input from the central nucleus of the amygdala, and projects back to the amygdala. [1]
Back part: connects both ways with the secondary somatosensory cortex and receives thalamic input carrying body-state signals such as pain, temperature, itch and touch. [1]
In human diffusion imaging, the anterior insula is wired to regions of the temporal and occipital lobes, the opercular and orbitofrontal cortex, and the inferior frontal gyrus. [1]
The ventral anterior cingulate cortex (Brodmann area 24) sends projections to the anterior insula. [3]
Inside it
The central sulcus of the insula divides it into a front part, made of three or four short gyri, and a back part, formed by a long gyrus. [1]
Its cell structure changes along its length, from granular at the back to agranular at the front; the anterior insula contains spindle neurons (von Economo neurons). [1]
Other names
Also called the insular cortex or insular lobe; plural insulae. [1]
First described by Johann Christian Reil; Henry Gray’s Gray’s Anatomy made it known as the Island of Reil. [1]
Size
On this model the left insula measures about 52 mm front to back, 35 mm top to bottom and 19 mm side to side (the box it fits in, not its volume); the right one is its mirror image. [4]
Centre of the left insula compared with the centre of the left temporal lobe: 24 mm further forward, 24 mm higher, 7 mm closer to the midline; 35 mm apart in a straight line. [4]
Centre of the left insula compared with the centre of the left putamen: 7 mm higher, 9 mm further from the midline; 12 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.