The smaller, anteromedial, "pars nervosa" compartment contains CN IX, (tympanic nerve, a branch of CN IX), and receives the venous return from inferior petrosal sinus. The larger, posterolateral, "pars vascularis" compartment contains CN X, CN XI, Arnold's nerve (or the auricular branch of CN X involved in the Arnold's reflex, where external auditory meatus stimulation causes cough), jugular bulb, and posterior meningeal branch of ascending pharyngeal artery.