Background: Endoscopic sinus surgery (ESS) is a technique which carries great potential benefits for the treatment of many nasal conditions. However, it also carries substantial risks. The key to safe surgery lies with adequate training .While dissection of cadaveric human heads is essential in learning nasal and sinus anatomy, and in practicing techniques, it is often difficult to obtain a supply of human heads that are accessible to trainees.
Aim of work: Was comparing CT scan of sheep nose and paranasal sinuses
with that of human and studying the anatomy of the lateral wall of the nose of the sheep and comparing with that of human.
Material and Methods: It was be performed on 14 heads of sheep (rahmani) purchased fresh from an abattoir. The 14 heads were classified into: Group (1) 4 heads were subjected to CT scan. Group (2) 6 heads were subjected to anatomical dissection. Group (3) 4 heads were subjected to Endoscopic examination. The following was performed: Coronal CT scan was done to 4 heads with cuts at 5 mm spacing 2 mm slice thickness . Scan was started just after the nares, 30 slices were acquired. Anatomical dissection of the head by :Heads were divided two subgroups: Subgroup A Included 3 heads and were dissected sagittally.subgroup B Included 3 heads and were dissected coronally. The endoscopic examination was carried out on group(3) using a rigid endoscope with a diameter of 4 mm. The endoscope was inserted into the ventral nasal passage of the left side and moved forward along the nasal septum up to the region of the pharynx.
Results: The CT scans and anatomical dissection showed that, the shape of sheep nose is conical, it is narrow anteriorly and wide posteriorly with a length ranging from (16-20) cm, a height was measuring 6-10cm and a width of 7.5-9cm at widest points. The opening of Para nasal sinuses lies in the middle meatus like that of the human. CT scan and anatomical dissection showed that the nasal cavity of the sheep was narrowed by the bullous nature of the inferior concha.
Conclusion: Using the sheep head model provides a cheap, practical and safe method for teaching basic nasal and sinus endoscopy techniques. The sheep proved to be the most useful animal both in terms of general nasal anatomy and in the depth of the nose being accessible to the endoscope used in humans. Although the anatomy of the head of the sheep is evidently different from that of the human, the nasal cavity itself is very similar in appearance, though somewhat wider.