Inferior frontal sulcus
Sulcus frontalis inferior
A groove on the outer surface of the frontal lobe that runs forwards from the precentral sulcus and divides the middle frontal gyrus from the inferior frontal gyrus.
At a glance
- English
- Inferior frontal sulcus
- Latin (TA2)
- Sulcus frontalis inferior
- System
- Brain and spinal cord
- Region
- Head
- Side
- Paired, left and right
About the inferior frontal sulcus
The inferior frontal sulcus is the lower of the two long furrows on the lateral face of the frontal lobe. It begins behind at the precentral sulcus, usually joining its lower part, and runs forwards and slightly downwards towards the front of the lobe. Above it is the middle frontal gyrus; below it is the inferior frontal gyrus, which borders the lateral sulcus and the edge of the orbit.
The gyrus beneath it is cut by the anterior and ascending rami of the lateral sulcus into three parts. From back to front these are the opercular part, which overlies the insula behind the ascending ramus; the triangular part, wedged between the two rami; and the orbital part, which turns onto the underside of the lobe. The sulcus therefore forms the upper limit of all three. Like the superior frontal sulcus it may be broken into segments by small bridging folds.
The cortex on either side of the sulcus has distinct roles. In the dominant hemisphere, usually the left, the opercular and triangular parts of the inferior frontal gyrus form Broca's area, which is essential for producing fluent speech and for building sentences. The middle frontal gyrus above contains much of the dorsolateral prefrontal cortex, involved in working memory, planning and control of attention. The sulcus is also part of the inferior frontal junction, where it meets the precentral sulcus, a region active in switching between tasks.
Both gyri are supplied by branches of the superior division of the middle cerebral artery, which emerge from the lateral sulcus and climb over the frontal operculum. Occlusion of this division typically produces Broca aphasia with weakness of the opposite face and arm. In awake brain surgery the sulcus helps the team locate language cortex before stimulation mapping.
Function and supply
- Function
- A surface landmark between the middle and inferior frontal gyri; the flanking cortex includes Broca's speech area below and dorsolateral prefrontal cortex above.
- Blood supply
- Frontal branches of the superior division of the middle cerebral artery.
Anthromica
See the inferior frontal sulcus where it really sits, with every layer of the body around it.
- Every layer, one body. Peel from muscle to bone, nerve, vessel and organ, and turn it any way.
- English and Latin. Every structure named the way your exam names it.
- Quiz until it sticks. Short drills on the structures you keep missing.
Free to start. No card.
