This is a triangular space bounded by –
Bony labyrinth anteriorly
Sigmoid sinus posteriorly
Dura containing superior petrosal sinus superiorly.
This triangle is a potential weak spot through which infections of temporal bone may traverse and affect cerebellum. Extra dural abscess involving the posterior cranial fossa is also possible when thin bone in this triangle gets breached in infections / cholesteatoma involving mastoid cavity.Since bone in this area is rather thin it can be drilled out to enter into the posterior cranial fossa. This can be used as an approach to posterior cranial fossa lesions.
The size of this triangle is highly variable depending on the size of the sigmoid sinus. A large sigmoid sinus reduces the size of this triangle and also increases the angulation of the superior petrosal sinus with it. This impedes the venous drainage predisposing to the development of endolymphatic hydrops.