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Orbital gyri

The orbital gyri are a group of cortical gyri located on the inferior (orbital) surface of the frontal lobe. They form a major part of the orbitofrontal cortex and are involved in higher-order cognitive processes including decision-making, emotional regulation, reward processing, and social behavior.

Due to their location adjacent to the orbits and anterior cranial fossa, the orbital gyri are particularly vulnerable to traumatic injury, tumors, and inflammatory processes and are frequently evaluated in neuroimaging.

Synonyms

  • Orbital surface gyri of the frontal lobe

  • Orbitofrontal gyri

  • Gyri orbitales

Location

  • Situated on the inferior surface of the frontal lobe

  • Rest on the orbital plates of the frontal bone

  • Anterior to the olfactory trigone

  • Inferior to the frontal pole

  • Medial to the lateral orbital sulcus

  • Separated from the gyrus rectus by the olfactory sulcus

Anatomical components

  • Medial orbital gyrus

  • Anterior orbital gyrus

  • Posterior orbital gyrus

  • Lateral orbital gyrus

  • H-shaped orbital sulcus:

    • Divides the orbital surface into multiple gyri

    • Key landmark on inferior frontal lobe anatomy

Relations

Inferiorly:

  • Orbits and orbital fat

  • Orbital plates of the frontal bone

Superiorly:

  • Frontal white matter

  • Superior frontal and middle frontal gyri (via cortex continuity)

Medially:

  • Gyrus rectus

  • Olfactory sulcus and olfactory bulb

Laterally:

  • Inferior frontal gyrus

  • Lateral orbital sulcus

Posteriorly:

  • Anterior perforated substance

  • Insular region (deep)

Vascular supply

  • Orbitofrontal branches of the anterior cerebral artery (ACA)

  • Orbital branches of the middle cerebral artery (MCA)

  • Small perforating cortical arteries

Function

  • Decision-making: Evaluation of reward, punishment, and risk

  • Emotional regulation: Modulation of affect and impulse control

  • Social behavior: Interpretation of social cues and behavioral inhibition

  • Olfactory integration: Higher-order processing of smell-related information

  • Executive control: Integration of sensory input with goal-directed behavior

Clinical significance

  • Traumatic brain injury: Commonly affected in coup–contrecoup injuries due to frontal bone proximity

  • Orbitofrontal syndrome: Personality changes, disinhibition, impulsivity, and poor judgment

  • Tumors: Meningiomas, gliomas, and metastatic lesions may involve orbital gyri

  • Epilepsy: Seizure focus in some cases of frontal lobe epilepsy

  • Neurodegenerative disease: Early involvement in frontotemporal dementia

  • Olfactory disturbances: Lesions may affect smell perception and integration

MRI appearance

T1-weighted images:

  • Normal cortex: Intermediate signal intensity with clear gray–white matter differentiation

  • Orbital gyri: Thin cortical ribbon following the inferior frontal surface

T2-weighted images:

  • Normal cortex: Intermediate-to-slightly hyperintense signal

FLAIR:

  • Normal: Uniform cortical signal

Diffusion-weighted imaging (DWI):

  • Normal: No diffusion restriction

Post-contrast T1-weighted images:

  • Normal: Minimal or no enhancement

CT appearance

Non-contrast CT:

  • Normal: Gray–white matter differentiation preserved

  • Trauma: Common site for hemorrhagic contusions

Post-contrast CT:

  • Normal: Minimal cortical enhancement

MRI images

MRI Orbital gyri axial anatomy image -img-00000-00000

MRI images

MRI Orbital gyri coronal anatomy image -img-00000-00000

MRI images

MRI Orbital gyri sag anatomy image -img-00000-00000_00001