inferior ramus of the arcuate sulcus

inferior ramus of the arcuate sulcus (iras)

The term inferior ramus of the arcuate sulcus refers to the lower, diagonal branch of the arcuate sulcus in the frontal lobe of the macaque. Defined by dissection, it separates the precentral gyrus caudally from the inferior frontal gyrus rostrally ( Martin-2000 ). Architectonically it separates the premotor cortex caudally from the dorsolateral prefrontal cortex rostrally. It may be homologous to the inferior precentral sulcus of the adult human ( See arcuate sulcus for details. ) Equivalent structures are not found in the smooth cerebral cortex of the rat or mouse ( NeuroNames ).

Also known as: Ramus inferior sulcus arcuatus, vertical arcuate sulcus, vertical ramus of arcuate sulcus, inferior arcuate sulcus, inferior ramus of the arcuate sulcus

NeuroNames ID: 65

All Names & Sources

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English

inferior arcuate sulcus

Matelli-2004

English

inferior ramus of the arcuate sulcus

Szabo-1984

English

vertical arcuate sulcus

Krieg-1975

English

vertical ramus of arcuate sulcus

Walker-1940

Illustrations

Showing 3 illustration(s)

drawing of
all aspects in
human

labeled line drawings of
sagittal section in
Macaca fascicularis

drawing of
all aspects in
macaque

Species With The Structure

Equivalent By	Human	Macaque	Rat	Mouse
Topology	Relevant Data Not Located	Has The Structure	Does Not Have The Structure	Does Not Have The Structure

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Basis

Has Equivalent

Organism

Their Name

Source

Topology

Yes

Macaca mulatta (Macaca mulatta)

vertical arcuate sulcus

Topology

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Topology

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Models Where It Appears

Structural CNS Model - Macaque

Brain structures of the macaque are illustrated in BrainInfo’s NeuroMaps macaque brain atlas. Structures are grouped by proximity in a hierarchy corresponding to the central nervous system hierarchy of NeuroNames ( Bowden-1995 Martin-2000 ). Structures in the NeuroMaps atlas are based on the segmentation of an MRI of the brain of a 3-year old male rhesus macaque (Macaca mulatta). The atlas is most useful for targeting structures for implantating electrodes and chemtrodes. Updated 29 Oct 2025.

brain

forebrain

cerebrum (endbrain)

cerebral cortex (cortical plate)