All of the following from the boundary of MacEwen's triangle except
Temporal line
Posterosuperior segment of bony external auditory canal
Promontory
Tangent drawn to the external auditory meatus
Bounded by Temporal line, the Posterosuperior segment of a bony external auditory canal, Tangent drawn to the external auditory meatus. Impoant landmark to locate mastoid antrum in mastoid surgery. Ref: Dhingra 6th edition
Ear