Cuneus

Thecuneus is a wedged-shaped gyrus that is delineated byregion on the medial surface of the occipital lobe.

Relations

Anterosuperiorly the parieto-occipital sulcus separates the cuneus from the precuneus of the parietal lobe.

Posteroinferiorly the cuneus abuts the calcarine sulcus which separates it from the lingual gyrus¹.

The parieto-occipital sulcus anteriorly and the inferior sagittal sinus inferiorly. Its posterior aspect rests over the posterior section of the calcarine sulcus, join to form a "Y". lingual gyrus and occipital pole¹.

Blood supply

Blood supply to the cuneus is via the calcarine artery and parieto-occipital artery. The proportion varies from person to to person and either artery can be the major source of perfusion².

Function

Fibres of the superior optic radiation corresponding to the inferior quadrant of the visual field synapse on the cuneus³.

Magneto encephalographic (MEG) measurements of occipital cortical signals have shown that the anteromedial cuneus activates almost simultaneously with the primary visual cortex (3-4 ms delay) in response to a visual stimulus and may act to modulate signals travelling from the primary visual cortex to the extrastriate cortices⁴.

Related pathology

Lesions of the cuneus result in an inferior contralateral quadrantanopia³.

Beyond its role in vision, a reduction of cortical thickness of the cuneus has has also been associated with the pathogenesis of trigeminal neuralgia⁵, as well as the development of psychosis in patients with a history of herpes simplex virus type 1 infection⁶. 

An MRI study found that thinning of posterior cortical regions, including the cuneus, is closely correlated with the occurrence and severity of visual hallucinations in dementia with Lewy bodies⁷.