The frontotemporal peripheral nerves. Topographic variations of the supraorbital, supratrochlear and auriculotemporal nerves and their possible clinical significance

The peripheral topography of the supraorbital (SON) and supratrochlear (STN ) nerves and the superficial temporal branch of the auriculotemporal nerve (ATN) was investigated in 10 cadavers. The aim was to define the optimal lo cations for anaesthetic nerve blocks. as well as to help surgeons prevent n erve injuries. Specific measurements on the nerve "exits" in relation to de fined landmarks are presented. The variability of the supraorbital notches and peripheral branching of the dissected nerves suggests several methods f or anaesthetic blocks in cases of surgical and clinical head pain. The opti mum injection site for a selective SON block is 20-30 mm from the midline ( range 15-33 mm), reinjection at 30-50 mm from the midline might complete in efficient nerve block. For selective SON block the distance between the mai n SON and STN branches (mean 15.3 mm) should also be considered. The ATN is best blocked at a point located at the level with and 10-15 mm (range 8-20 mm) anterior to the upper origin of the helix. Separate exits for the medi al and lateral SON branches were observed in eight of the 20 nerves examine d. Twenty of the 28 exits were foraminae completed by bony or connective ti ssue. In many cases both the SON and STN ascended close to the associated a rtery: in six cases a tissue band covered the nerve and vessel at the orbit al exit. Some of the observed structures associated with the nerve might be pain-generators, however the present study does not provide any evidence f or such a hypothesis.