Alireza Vajhi - Department of Surgery and Radiology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.
Mohammad Reza Mokhber Dezfouli - Department of Internal Medicine, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.
Omid Zehtabvar - Anatomy Sector, Department of Basic Science, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.
Sirous Sadeghian Chaleshtori - Department of Internal Medicine, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.
Seyyed Hossein Modarres Tonekabony - Doctor of Veterinary Medicine, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.
Reihaneh Soflaei - Veterinary Radiology DVSc Student, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.
Javad Abbasi - Department of Large Animal Internal Medicine, Karaj Branch, Islamic Azad University, Karaj, Iran.

Understanding anatomical structures from the past to the present has been one of the guidelines for advancing medical and veterinary science worldwide. The lack of comprehensive information on the anatomy of the paranasal sinuses and the Shal sheep nasal cavity (Ovis aries) encouraged us to write this article. Computed tomography (CT) scan is a method that shows different parts of the body without superimposition of adjacent structures. Radiographic imaging also gives very high-resolution images of bones to examine bone structures. Paranasal sinuses of Shal sheep were composed of frontal, maxillary, lacrimal, and palatine sinuses, and the nasal sinuses were composed of dorsal, and middle nasal sinuses, which were identified and labeled in keeping with cheek teeth as landmarks. The width of the frontal bone and length of the nasal cavity at the level of the ۶th cheek tooth were ۷ ± ۰.۳ and ۱۳ ± ۰.۸ cm, respectively. The volumes of both the right and left sinuses were measured automatically, and the accurate location of sinuses, canals, nasal folds, conchae, and meatuses, and connections between different parts of the nasal cavity and paranasal sinuses were described. The volume of the frontal, maxillary, and palatine sinuses were ۲۷۹.۳ ± ۱۶.۴, ۸۰.۶ ± ۲.۶, and ۱۳.۵ ± ۰.۲ cm۳, respectively. Frontal, maxillary, and lacrimal sinuses were observed like other ruminants. But the palatine sinus in this breed was not present in the Egyptian sheep, Saanen, and Markhz goats. Also, unlike Sanan and Markhz goats and like Egyptian sheep, ventral nasal sinus was not observed in this breed.

Computed Tomography, Volumetric study, Morphometric study, Sheep, Skull