Wednesday, February 9, 2011

Superior Longitudinal Fasciculus

The superior longitudinal fasciculus is a thick and long bundle of myelinated axons which links the frontal lobe to the occipital, and part of the parietal and temporal lobes of each cerebral hemisphere. The association fibers that constitute the superior longitudinal fasciculus are bi-directional, which means that some axons originate in cortical neurons of the frontal lobe, while others in neurons located in the occipital and back regions of the temporal and parietal lobes, integrating motor and decision-making centers with visual and sensory ones. The superior longitudinal fasciculus sweeps along the superior margin of the claustrum in a great arc.

The superior longitudinal fasciculus consists of three distinct components: 1) SLF I is the dorsal component and originates in the superior and medial parietal cortex, passes around the cingulate sulcus and terminates in the dorsal and medial cortex of the frontal lobe and in the supplementary motor cortex; 2) SLF II is the major component of SLF and originates in the caudal-inferior parietal cortex and occipital lobe, ending in the dorsolateral prefrontal cortex (Brodmann 6, 8 and 46); 3) SLF III is the ventral component which begins in the supramarginal gyrus (rostral portion of the inferior parietal lobe) and ends in the ventral premotor and prefrontal cortex (Brodmann 6, 44, and 46).