Length of Eustachian tube?: (A) 12 mm, (B) 24mm, (C) 36mm, (D) 48mm
Answer is C. Length of Eustachian tube is 36 mm. (reached by the age of 7 years) Lateral third (i.e. 12 mm) is bony. Medial 2/3 (i.e. 24 mm) is fibrocailaginous.