The posterior auricular nerve
arises close to the stylomastoid foramen
and runs upward in front of the mastoid process
; here it is joined by a filament from the auricular branch
of the vagus
and communicates with the posterior branch of the great auricular
as well as with the lesser occipital
As it ascends between the external acoustic meatus and mastoid process it divides into auricular and occipital branches.