On the duality of the facial nerve ganglion

Objectives: Describe quantitatively the number of ganglion cells in the geniculate (G) and meatal (M) segments of the human facial nerve. Study Design: 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. Methods: 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. Results: 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, Conclusions: 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,