3D models of the sinonasal channels and the SMR, SCV and SMC of a 3-year old Warmblood mare. In a dorso-medial view of the right side (A), the middle nasal meatus (black arrow), the nasomaxillary aperture (white arrows) and the sinonasal channel system (blue) are visible. The dorsal view gives an overview of the different parts of the sinonasal channels (B): The broken lines border the common sinonasal channel (Canalis sinunasalis communis). The green arrow lies within the rostral sinonasal channel (Canalis sinunasalis rostralis), whereas the red arrow lies within the caudal sinonasal channel (Canalis sinunasalis caudalis). Coloured structures: bright green: SMR, dark green: SCV, red: SMC, blue: sinonasal channel system.