Angular gyrus

At a glance

English

Angular gyrus

Latin (TA2)

Gyrus angularis

System

Brain and spinal cord

Region

Head

Side

Paired, left and right

About the angular gyrus

The angular gyrus lies in the lower part of the parietal lobe, in the region called the inferior parietal lobule. It sits just behind the supramarginal gyrus and curves around the upturned back end of the superior temporal sulcus, near the upper margin of the temporal lobe. Because of this position it borders the parietal, temporal and occipital lobes and is often described as lying at the meeting point of the lobes. It corresponds roughly to Brodmann area 39. The angular gyri of the two hemispheres are connected through the back of the corpus callosum, in the splenium and isthmus.

Its location places it between the cortex that processes vision, hearing and touch, and it acts as a high-level association area that combines these streams. In the language-dominant (usually left) hemisphere it forms part of the posterior language territory beside Wernicke's area, and it is classically seen as the place where the seen form of a word is linked to its sound and meaning. It is active in reading and writing, in recalling arithmetic facts for exact calculation, and in retrieving the meaning of words.

Beyond language it takes part in several wider functions. It is a key node of the default mode network, the set of regions that is active when the mind is turned inwards rather than to the outside world, and it contributes to memory retrieval, to judging other people's intentions and to directing attention. The right angular gyrus helps orient attention in space and to striking features. It also compares intended movements with their effects, helping a person sense that an action is their own. Stimulating the right-sided gyrus electrically during brain surgery has produced out-of-body sensations, which suggests a role in combining body position with the sense of self.

Damage to the left angular gyrus, most often from a stroke in the territory of the middle cerebral artery, causes Gerstmann syndrome: difficulty writing (agraphia), difficulty with arithmetic (acalculia), inability to name or tell apart the fingers (finger agnosia) and confusion between left and right. Lesions here can also cause alexia with agraphia, a loss of both reading and writing. Damage on the right can contribute to neglect of the left side of space.

Function and supply

Function

Combines visual, auditory and bodily information for reading, writing, word meaning and exact calculation; contributes to spatial attention, left-right orientation, memory retrieval, the sense of agency and the default mode network.

Blood supply

Supplied by the angular branch of the middle cerebral artery, with a contribution from the posterior cerebral artery at its back edge.