Referred pain from the sphenoid sinus
Red flag: Please note that sphenoid sinusitis often results in referred pain to the vertex of the head; the junction between Vi and C2 dermatomes.
Innervation of the sphenoid sinus: Sensory innervation is by the posterior ethmoidal nerves. Postganglionic parasympathetic fibres of the facial nerve that synapse in the pterygopalatine ganglion control mucous secretion.
Level 1