Quantitative and histomorphological studies on the geniculate ganglion of the facial nerve in man.

The human geniculate ganglion was studied histologically and quantitatively. It appeared pyramidal in shape. The mean diameter of the side of the triangle constituting its base was 1,050 micrometer and its mean height 1,800 micrometer; the volume of the ganglion was 26 X 10(7) micrometer 3. The ganglionic cells were arranged in clusters with longitudinally extending bundles of nerve fibres in between. At the apex of the ganglion compact neurons were delineated from those in the rest of the ganglion by a bundle of nerve fibres. Moreover, scattered solitary nerve cells were met with between fibres of the greater petrosal and the chorda tympani nerves. The mean neuronal population was 1,070, the mean cell volume 11,913 micrometer 3, the cell territory 242,990 micrometer 3 and the volume of the intercellular space 231,077 micrometer 3. Extraganglionic vessels approximated the ganglion perpendicular to its long axis, while further intraganglionic vessels extended in a direction parallel to the long axis of the ganglion and vertical terminal ramifications formed dense vascular channels around the capsule of the nerve cells. The significance of that pattern of blood supply was discussed.