From anterior two third of tongue lingual nerve carries the taste sensation and through the chorda tympani it joins to the facial nerve. The taste sensations are tested as described below:
Solutions of five percent sucrose, one percent acetic acid, five percent sodium chloride and 0.5% quinine sulfate, cotton tipped applicator sticks.
To test the sense of taste use strong solution of sugar (for sweet), common salt (for salt), weak solution of citric acid (for sour) and quinine (for bitter). Four vials of solutions, salt, acetic acid and quinine are placed on the table with labels. Dry the tongue with paper towel and apply 5% sucrose solution with the applicator stick/glass rod to the tip, sides and back of the tongue. The different tastes are written on a paper and the subject is asked to point out the taste which he is tasting. The patient is asked to keep the tongue protruded, while applying one solution at a time. The same procedure is repeated with 1% acetic acid, 5% NaCl and 0.5% quinine sulphate. These substances are applied on each side of the tongue and the patient should be able to identify. After each taste mouth must be rinsed. Both the anterior and posterior part of the right and the left halves of the tongue should be tested separately. The quinine solution should be tested in the last as effect is more lasting than that of others.