Computed Tomography, Magnetic Resonance, Cross‐Sectional Anatomy, and 3D Volume Rendering of the Nasal Cavity and Paranasal Sinuses of the Alpaca ( <i>Vicugna pacos</i> )

ABSTRACT Understanding the anatomy of the paranasal sinuses and nasal cavity in alpacas ( Vicugna pacos ) is limited by scarce published data. This prospective cadaveric study aimed to enhance the interpretation of clinical cross‐sectional imaging and expand knowledge of normal anatomy using computed tomography (CT), magnetic resonance imaging (MRI), macroscopic cross‐sections, and 3D reconstructions (Amira v5.3.3; Thermo Fisher Scientific, Waltham, MA, USA). Seven alpacas (median age 3.9 years; five males, two females) underwent CT and MRI. Frozen anatomical slices were obtained from three heads, and sinus fenestration from one. All specimens had a conchal (dorsal and middle), maxillary, frontal, and ethmoidal sinus. The 6/7 specimens presented a sphenoidal sinus, and 5/7 specimens presented bilateral lacrimal sinuses. Notably, the ventral conchal and palatine sinuses were absent in all specimens. The frontal sinus was divided into a smaller, non‐concamerated, medial compartment and a large, diversely concamerated, lateral compartment in all specimens, except one in which only a common frontal sinus was present. The sphenoidal sinus was divided by a variably thickened septum in 3/6 heads. The ethmoidal bone contained air‐filled cells divided into lateral and medial groups. The lateral cells presented a lengthier rostro‐caudal extension and connected to the frontal, lacrimal, and maxillary sinuses, whereas the medial cells were shorter and surrounded the middle conchal sinus.