The arcuate fasciculus (AF) has been classically described as a connection between Broca’s area and Wernicke’s area 1. However, the location and connectivity of the fibers of the AF is variable. The AF is composed of a direct and indirect component 2.
Anatomy
Direct Component
The direct component of the AF lies dorsal to the external capsule and deep to the insular cortex 2. Fibers of the direct component of the AF connect the caudal portion of the superior temporal lobe with the caudal dorsal premotor and prefrontal cortices 3.
Indirect Component
Most of the frontal fibers of the anterior indirect segment of the AF run from the ventral precentral gyrus and posterior portion of the pars opercularis to the supramarginal gyrus. Fibers are oriented horizontally.
The fibers of the posterior indirect segment of the AF extend from the posterior portion of the middle temporal gyrus to the angular gyrus. Fibers within the posterior indirect segment are oriented vertically.
The fibers of the long segment are located at the deep aspect of the anterior and posterior segments of the AF. Anteriorly, the long segment is connected to the ventral precentral gyrus and the pars opercularis. Posteriorly, fibers of the long segment are connected to the middle temporal gyrus and the inferior temporal gyrus. 4
Related Pathology
Isolated lesions to the AF are rare. Although some studies describe conduction aphasia due to lesion of the AF, damage to the AF is not necessary for conduction aphasia and some patients with damage to this structure may retain the ability to repeat language 5–7. The exact role of the AF remains unclear, however some studies suggest the AF may play a role in spatial localization of auditory stimuli. 3
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