Orbital part of inferior frontal gyrus

At a glance

English

Orbital part of inferior frontal gyrus

System

Brain and spinal cord

Region

Head

Side

Paired, left and right

About the orbital part of inferior frontal gyrus

The inferior frontal gyrus is cut by two short branches of the lateral sulcus into three sections. The orbital part, or pars orbitalis, is the most anterior and inferior of them. It lies in front of and below the anterior limb of the lateral sulcus, often called the horizontal ramus, which separates it from the triangular part above and behind. Below, it is bounded by the stem of the lateral sulcus, and it turns round the lower edge of the frontal lobe to become continuous with the lateral orbital gyrus on the underside of the brain.

Its position makes it a bridge between the lateral and orbital surfaces of the frontal lobe. It lies above the front of the temporal pole and the lateral orbital wall, and forms the most anterior part of the frontal operculum over the front of the insula.

Its cortex corresponds to Brodmann area 47, which shares features with neighbouring orbitofrontal cortex; in many schemes it is called area 47/12. In the left hemisphere it lies just in front of Broca's area. Imaging studies link it with the meaning of words and sentences, with retrieving words by meaning, and with processing the structure of music and language. Like the orbitofrontal cortex beside it, it also takes part in emotional evaluation and in the control of behaviour.

Damage confined to this region is uncommon. When it is affected with the rest of the inferior frontal gyrus, as in strokes of the upper division of the middle cerebral artery or in frontal tumours and injuries, it adds to the language difficulty and may change judgement and behaviour.

Function and supply

Function

Brodmann area 47; involved in the meaning of words and sentences, word retrieval and, with nearby orbitofrontal cortex, emotional evaluation.

Blood supply

Lateral orbitofrontal branch of the middle cerebral artery.