The inferior or orbital surface of the

frontal lobe The frontal lobe is the largest of the four major lobes of the brain in mammals, and is located at the front of each cerebral hemisphere (in front of the parietal lobe and the temporal lobe). It is parted from the parietal lobe by a groove betwe ...

is concave, and rests on the orbital plate of the frontal bone. It is divided into four orbital gyri by a well-marked H-shaped

orbital sulcus The inferior or orbital surface of the frontal lobe is concave, and rests on the orbital plate of the frontal bone The frontal bone is a bone in the human skull. The bone consists of two portions.'' Gray's Anatomy'' (1918) These are the vertical ...

. These are named, from their position, the medial, anterior, lateral, and posterior, orbital gyri. The medial orbital gyrus presents a well-marked antero-posterior sulcus, the

olfactory sulcus The olfactory tract is a bilateral bundle of afferent nerve fibers from the mitral and tufted cells of the olfactory bulb that connects to several target regions in the brain, including the piriform cortex, amygdala, and entorhinal cortex. It ...

, for the

olfactory tract The olfactory tract is a bilateral bundle of afferent nerve fibers from the mitral and tufted cells of the olfactory bulb that connects to several target regions in the brain, including the piriform cortex, amygdala, and entorhinal cortex. It ...

; the portion medial to this is named the straight gyrus, and is continuous with the

superior frontal gyrus In neuroanatomy, the superior frontal gyrus (SFG, also marginal gyrus) is a gyrus – a ridge on the brain's cerebral cortex – which makes up about one third of the frontal lobe. It is bounded laterally by the superior frontal sulcus. The su ...

on the medial surface.

Function

Bailey and Bremer reported that stimulation to the central end of the

vagus nerve The vagus nerve, also known as the tenth cranial nerve, cranial nerve X, or simply CN X, is a cranial nerve that interfaces with the parasympathetic control of the heart, lungs, and digestive tract. It comprises two nerves—the left and right ...

caused electrical activity in the inferior orbital surface (http://brain.oxfordjournals.org/cgi/pdf_extract/75/2/244)

Additional images

File:Orbital gyrus animation2.gif, Orbital gyri shown in red. File:FrontalCaptsBasal.png, Orbital surface of brain. File:Slide2STE.JPG, Close up of orbital gyri. File:Orbital gyrus viewed from bottom.png, Human brain bottom view. Orbital gyri shown in red. File:Tuberculous leptomeningitis.jpg, Human brain bottom view. Orbital gyri not labelled, but seen at top.

References

External links

* https://web.archive.org/web/20100406032835/http://anatomy.med.umich.edu/atlas/n1a2p13.html Cerebrum Gyri Frontal lobe {{neuroanatomy-stub