Fig. 1

Photographs of a right-paramedian dissected equine skull (a + b left side, lateral views; c + d left side, medial view). During sample collection skin and musculature were transected (a), the eye and parts of the maxillary bone were removed (b), skulls were transected sagittally and the nasal septum was removed (c) and parts of the nasal conchae were removed (d). The yellow coloured boxes mark the nine different sample sites. a Frontal sinus, FS (1), caudal maxillary sinus, CMS (2), rostral maxillary sinus, RMS (3); b Caudal maxillary sinus, orbit, CMS-O (4); c Dorsal conchal sinus, DCS (5), middle conchal sinus, MCS (6), ventral conchal sinus, VCS (7) and frontal sinus septum, FSS (8); d Nasomaxillary aperture, NA (9)