Fig. 1

Schematic depiction of the trigeminal-autonomic reflex and related areas. Sensory afferents from cranial structures synapse in the trigeminal nucleus caudatus. Input is relayed to the brainstem and higher structures including the periaqueductal grey (PAG) and hypothalamus. Likewise, descending modulatory hypocretinergic connections are received from the hypothalamus. SSN – superior salivatory nucleus, TNC – trigeminal nucleus caudalis (trigeminal complex), PG – ptyrogopalatine (sphenopalatine) ganglion, TG – trigeminal ganglion. With permission from Holland et al. 2009 (Springer)