Association fiber

Association fibers are axons that connect cortical areas within the same cerebral hemisphere.[1]

Association fiber
Diagram showing principal systems of association fibers in the cerebrum.
Dissection of cerebral cortex and brainstem showing association fibers and insular cortex after removal of its superficial grey matter
LatinFibrae associationis telencephali
Anatomical terms of neuroanatomy

In human neuroanatomy, axons (nerve fibers) within the brain, can be categorized on the basis of their course and connections as association fibers, projection fibers, and commissural fibers.[1]

The association fibers unite different parts of the same cerebral hemisphere, and are of two kinds: (1) short association fibers that connect adjacent gyri; (2) long association fibers that make connections between more distant parts.

Short association fibers

Many of the short association fibers (also called arcuate or "U"-fibers) lie immediately beneath the gray substance of the cortex of the hemispheres, and connect together adjacent gyri.[2] Some pass from one wall of the sulcus to the other.[2]

Long association fibers

The long association fibers connect the more widely separated gyri and are grouped into bundles.[2] They include the following:

uncinate fasciculusfrontal lobetemporal lobe
cingulumcingulate gyrusentorhinal cortex
superior longitudinal fasciculusfrontal lobeoccipital lobe
inferior longitudinal fasciculusoccipital lobetemporal lobe
vertical occipital fasciculusinferior parietal lobulefusiform gyrus
occipitofrontal fasciculusoccipital lobefrontal lobe
Arcuate fasciculusfrontal lobetemporal lobe

Diffusion tensor imaging is a non-invasive method to study the course of association fibers.

See also


  1. Standring, Susan (2005). Gray's Anatomy: The Anatomical Basis of Clinical Practice (39th ed.). Churchill Livingstone. pp. 411. ISBN 9780443071683. The nerve fibres which make up the white matter of the cerebral hemispheres are categorized on the basis of their course and connections. They are association fibres, which link different cortical areas in the same hemisphere; commissural fibres, which link corresponding cortical areas in the two hemispheres; or projection fibres, which connect the cerebral cortex with the corpus striatum, diencephalon, brain stem and the spinal cord.
  2. Standring, Susan (2005). Gray's Anatomy: The Anatomical Basis of Clinical Practice (39th ed.). Churchill Livingstone. pp. 411. ISBN 9780443071683. Association fibres may be either short association (arcuate or 'U') fibres, which link adjacent gyri, or long association fibres, which connect more widely separated gyri. Short association fibres may be entirely intracortical. Many pass subcortically betweena adjacent gyri, some merely pass from one wall of a sulcus to the other. Long association fibres are grouped into bunbles, ...
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