Horizontal Branch of Sylvian Fissure

The Horizontal Branch of the Sylvian Fissure (hbSF) separates the pars triangularis from the pars orbitalis, both sectors of the inferior frontal gyrus. It starts together with the abSF with which it may be linked. It runs posterior to anterior towards the descending segment of the IFS or the Lateral Orbital Sulcus which it rarely reaches.

The first point of the curve should be dropped posteriorly (3) followed by the anterior terminal point (4).

Parasagital slices can be of help to identify these two sulci (5). The two terminal branches form a V or Y , easily seen on parasagital slices as shown.

The combination of the pars opercularis and triangularis is usually called, in the left hemisphere, Broca's Area.

USC Biomedical Imaging Research Lab © 2009, designed by Dimitrios Pantazis