Dehiscence of anterior wall of the external auditory canal cause infection in the parotid gland via -
The cartilaginous part of external auditory canal—the “fissures of santorini” through which infections can pass from external ear to parotid and vice versa.
The deficiency present in bony part is “Foramen of Huschke” seen in children up to the age of 4. Through this infections of ear can also pass to parotid gland.

Ref. Dhingra 6/e, p 2, 5/e, p4
Fissure of santorini
Notch of rimus
Petrous fissure
Retropharyngeal fissure