Orbital gyri
Gyri orbitales
The four gyri on the concave underside of the frontal lobe, arranged around an H-shaped orbital sulcus above the roof of the orbit.
At a glance
- English
- Orbital gyri
- Latin (TA2)
- Gyri orbitales
- System
- Brain and spinal cord
- Region
- Head
- Side
- Paired, left and right
About the orbital gyri
The underside of the frontal lobe is called its orbital surface. It is concave from side to side and rests on the orbital part of the frontal bone, which forms the roof of the orbit, and on the lesser wing of the sphenoid. This surface is divided into a set of orbital gyri by the orbital sulci.
The pattern of these sulci is often likened to the letter H, though it varies a good deal between people and between hemispheres. Two roughly parallel limbs run from front to back and are joined by a transverse bar. The gyri are named from where they lie relative to this H: anterior, posterior, medial and lateral orbital gyri. The lateral orbital gyrus is continuous with the orbital part of the inferior frontal gyrus on the lateral surface, and the posterior orbital gyrus reaches back towards the anterior perforated substance.
Medially lies the olfactory sulcus, a straight groove close to the midline that holds the olfactory bulb and tract. Medial to this sulcus is the gyrus rectus, the straight gyrus, which continues up onto the medial surface of the hemisphere as the superior frontal gyrus. The medial orbital gyrus sits lateral to the olfactory sulcus.
Together these gyri make up much of the orbitofrontal cortex. This region receives smell, taste and visceral information, including signals that pass through the vagal pathways, and is involved in weighing reward and punishment, in decision making and in social behaviour and emotional control. Damage here, as in frontal head injury or tumours of the anterior cranial fossa such as olfactory groove meningioma, may cause disinhibited, impulsive behaviour with loss of smell.
Function and supply
- Function
- Form much of the orbitofrontal cortex, involved in smell and taste, evaluation of reward, decision making and social behaviour.
- Blood supply
- Orbitofrontal branches of the anterior cerebral artery medially and of the middle cerebral artery laterally.
Anthromica
See the orbital gyri 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.
