Anatomical review of the nasal cavities and the sinuses

The specificities of the equine nasal vestibule and nasal cavities (length, simple conchae, small size of the middle nasal concha, conchal sinuses, …) are first presented. The 5 sinuses of the horse are then described. The frontal (conchofrontal) sinus is divided in 2 compartments, separated by the ethmoid bone. It opens in the caudal maxillary sinus (and not in the nasal cavity) by the frontomaxillary opening. There are 2 maxillary sinuses, caudal and rostral ; each of them is divided in 2 compartments, lateral and medial, communicating above the infra-orbital canal which crosses them caudo-rostrally. The floor of the lateral compartment of each maxillary sinus is in relation with the alveoli of the last teeth (molars and, for the rostral maxillary sinus, last premolar) ; these relations vary with age ...