On the duality of the facial nerve ganglion

Describe quantitatively the number of ganglion cells in the geniculate (G) and meatal (M) segments of the human facial nerve.

One hundred human temporal bone specimens that were sectioned horizontally and stained with hematoxylin and eosin were selected from a temporal bone collection on the basis of minimal artifact and absence of pathology involving the facial nerve.

Cells with a nucleolus in all sections through the facial nerve were projected on tracing paper with a camera lucida and counted manually. A modified Abercrombie technique was employed to compute total cells in the G and M segments.

Ages of patients ranged from 1 month to 92 years; the male-to-female ratio was 56:44. The total number of cells in individual temporal bones ranged from 589 to 4183 (mean, 2162 cells). The range of cells in the G ganglion was from 66 to 4017 (mean, 1713 cells); in the M ganglion the number ranged from 0 to 2764 (mean, 448 cells). There was no correlation of total ganglion cell number to age or sex. The majority of cells were found in the G ganglion in 88% of temporal bones. In 8% temporal bones the majority of cells were in the M ganglion and in 4% the M and G ganglions contained an equal number of cells.

The facial nerve sensory ganglion consists of two components: G and M. The G ganglion outnumbers the M component in the majority of temporal bones (88%). The M ganglion was equal to or greater in number than the G ganglion in 12% of temporal bones.