Superior frontal gyrus

At a glance

English

Superior frontal gyrus

Latin (TA2)

Gyrus frontalis superior

System

Brain and spinal cord

Region

Head

Side

Paired, left and right

About the superior frontal gyrus

The superior frontal gyrus is a broad ridge along the top of the frontal lobe. It runs from the frontal pole backward, parallel to the longitudinal fissure, as far as the precentral sulcus, which separates it from the precentral gyrus. On the lateral surface it is bounded below by the superior frontal sulcus, beyond which lies the middle frontal gyrus. At the superior border of the hemisphere it turns over onto the medial surface, where it forms the medial frontal gyrus down to the cingulate sulcus and, at the back, the front part of the paracentral lobule. In front and below it reaches the orbital surface and merges with the gyrus rectus.

The gyrus makes up a large share of the frontal lobe. Its back part, just in front of the motor strip, contains much of the premotor cortex (Brodmann area 6) and, on the medial surface, the supplementary motor area, which plans sequences of movement and their timing and helps start them. Its front part belongs to the dorsolateral and dorsomedial prefrontal cortex (areas 8, 9 and 10), and a part of area 8 near the middle frontal gyrus is the frontal eye field, which directs voluntary gaze.

Functional imaging links the gyrus with working memory, especially for spatial information, with self-awareness and with attention. Its medial part contributes to the default mode network and to thinking about oneself and others. During epilepsy surgery, electrical stimulation of a small area on the left superior frontal gyrus has produced laughter accompanied by a feeling of mirth, with the person supplying an outside reason for it.

Damage to the supplementary motor area on one side can cause a temporary loss of spontaneous movement and speech on the opposite side, which usually recovers within weeks, and an alien limb phenomenon. Tumours and strokes of the anterior cerebral territory involving the gyrus may produce apathy and leg weakness.

Function and supply

Function

Its back part plans and starts movement (premotor cortex and supplementary motor area); its front part supports working memory, attention and self-awareness.

Blood supply

Mainly branches of the anterior cerebral artery; the lateral margin is supplied by branches of the middle cerebral artery.