ACUTE MASTOIDITIS Fig. 172. Schwartze's operation for acute rnastoiditis. A, Subperiosteal abscess over right mastoi Line of incision. The dotted line indicates a second incision which may have to be made in cases in v the sinus is to be exposed: C, Area of operation exposed: 1, Posterior root of zygoma; 2, Supram spine; 3, Tip of mastoid process. The area of operation lies within the triangle made by joining three points. D, Mastoid antrum opened: 1, Mastoid antrum; 2, Air cells at the tip; 3, Sinus i The gouge is shown in the position for removal of bone to expose the sinus. E, Removal of t mastoid. F, The operation completed: 1, Dura of middle fossa exposed; 2, Posterior belly of dig* muscle exposed by removal of mastoid lip; 3, Exposure of sigmoid sinus.