Anatomical variations of the ciliary ganglion with an emphasis on the location in the orbit

The ciliary ganglion is of outmost physiological importance, due to its involvement in pupillary light reflex circuits. The ciliary ganglion may be damaged during surgical procedures. Therefore, the aim of the study was to examine the anatomical variations of the ganglion with an emphasis in location in the orbit. Anatomical variations of the parasympathetic root of the ganglion were also examined and classified. 40 orbits were dissected. The orbital content was removed en bloc. The lateral rectus muscle was detached from its insertion and reflected. After the removal of the orbital fat, the ciliary ganglion was visualized. Then, the morphology, roots and location of the ganglion were assessed. The location of the ciliary ganglion varied from 17 to 83.7% (mean = 51.4%, median = 53%, SD 14.8%) of the distance between the point of the optic nerve emerging from the eyeball and the common tendinous ring (counting from the front). In most cases (55%) it was found between 50.1 and 75% of the distance between the back of the eye and the common tendinous ring, while in 37.5% of cases it was found between 25 and 50% of this distance. The parasympathetic root of the ciliary ganglion was variable. Its origin was from the nerve to the inferior oblique muscle in most of cases. In four cases (10%), the parasympathetic root of the ciliary ganglion was duplicated. The ciliary ganglion occupies a variable position with regards to the optic nerve. The parasympathetic root of the ganglion may be unusually short or doubled.