Middle frontal gyrus

At a glance

English

Middle frontal gyrus

Latin (TA2)

Gyrus frontalis medius

System

Brain and spinal cord

Region

Head

Side

Paired, left and right

About the middle frontal gyrus

The middle frontal gyrus is a wide strip of cortex that runs from front to back across the lateral (outer) surface of the frontal lobe. It lies bounded above by the superior frontal sulcus and below by the inferior frontal sulcus, with the superior frontal gyrus over it and the inferior frontal gyrus under it. Behind, it ends at the precentral sulcus, in front of the precentral (motor) gyrus; in front, it reaches towards the frontal pole and turns onto the orbital surface. It makes up a large share of the lateral frontal lobe.

It is often better thought of as a region than as a single tidy ridge. It is frequently split along its length by a shallow middle frontal sulcus into upper and lower tiers, and in some brains it is broken into pieces. Its back part joins the precentral gyrus, and its folds vary considerably between people.

The gyrus contains several important areas. Its posterior part, close to the precentral sulcus, holds the frontal eye field (around Brodmann area 8), which starts voluntary saccades to the opposite side and directs visual attention. Further forward, the middle frontal gyrus forms most of the dorsolateral prefrontal cortex (areas 9 and 46), which supports working memory, planning, switching between tasks and other executive functions. On the left, its back part (sometimes called Exner's area) is linked with handwriting. It has rich connections with the parietal lobe through the superior longitudinal fasciculus, and with the thalamus and basal ganglia.

Damage to the frontal eye field causes the eyes to deviate towards the side of the lesion, at least for a short time after an acute stroke, because the opposite field is unopposed; a seizure there drives them away. Damage to the dorsolateral prefrontal cortex leaves movement and sensation intact but impairs organisation, planning and flexible thinking. The region is a common target of transcranial magnetic stimulation in treating depression.

Function and supply

Function

Holds the frontal eye field, which directs voluntary eye movements and attention, and much of the dorsolateral prefrontal cortex, which supports working memory and executive control.

Blood supply

Branches of the superior division of the middle cerebral artery, with the anterior cerebral artery supplying its upper margin.