Tuning-fork for testing of the sensitivity to vibrations (pallanesthesia), by creating low vibrations and setting the fork onto bony prominences that are close to the surface, for example the first metatarsal joint, or the ankle.
Liniger, C., Albeanu, A., Bloise, D. & Assal, J. P., 1990. The Tuning Fork Revisited. Diabetic Medicine, 7(10), pp. 859-864 – http://www.ncbi.nlm.nih.gov/pubmed/2149682