Fascicular patterns of the hypoglossal nerve.

Hypoglossal-facial nerve transfer is a standard technique for facial-palsy reconstruction. The fascicular anatomy of the hypoglossal nerve may be important in determining strategies, when attempting to minimize atrophy of the tongue. The present study investigated hypoglossal fascicular anatomy by histomorphometric analysis of 10 human hypoglossal nerves. The nerve demonstrates a monofascicular topography in its proximal third and mid portions, becoming polyfascicular only in its distal third. The mean number of fascicles in the distal portion is 5.0, compared to 1.1 in the proximal and mid portions (p < .01). The mean number of myelinated axons in the hypoglossal nerve is 9200.