Background: The aim of this study was to investigate the diameters of the bony nasolacrimal canal by computed tomography in normal adult Mongolian population and the effect of gender and age on the nasolacrimal canal diameter. Methods: Using standart tomographic images, we measured the diameters, angle between the bony canal and nasal floor and length of the bony nasolacrimal duct in 150 patients without nasolacrimal duct disease. Results: The anterioposterior diameter of the bony nasolacrimal canal was 6.49± 1.06mm, transverse diameter was 4.56±0.9mm, angle between the bony canal and nasal floor was 69.6±8.1o. No significant difference in anterioposterior diameter and transverse diameter in gender. The angle between the bony canal and nasal floor was significantly greater in male. Conclusions This study may contribute to the establishment of a detailed anatomical and morphometric baseline of the bony nasolacrimal canal and provide useful information for the planning of interventions for nasolacrimal duct obstruction

Introduction: Khuumii (throat singing) is a unique form of art derived from the nomadic population of Central Asia, producing two or more “simultaneous” sounds and melodies through the organ of speech. Material and Methods: The aim of the study is to identify the anatomical structures involved in the formation of khuumii and the features and patterns of their functions and compare each type of khuumii as performed by Mongolian people. A total of 60 participants aged 18-60 years (54 men and 6 women) were selected by non-random sampling method using cross-sectional study. Statistical analysis was performed using SPSS 23 software using questionnaires, X-ray, endoscopy, sound research method, and general blood tests. Results: 90.7% of the khuumii singers were male and 9.3% were female. The average height of the participants was 172.91±0.93 cm (arithmetic mean and mean error), average body weight was 77.53±2.46 kg, and body mass index was 25.93±5.31 respectively. Heart rate was 92.19±20.71 per minute prior to khuumii while 133.19±19.09 after performing khuumii and 85.81-98.56 at 95% confidence interval. In terms of ethnicity (ethnographically), the Khalkh were the largest ethnic group (72.1%), followed by Bayad, Buryatia, Darkhad, Torguud, and Oirat (2.3%), respectively. 60.5% of the participants were professional khuumii singers who graduated from relevant universities and colleges. The process of Khuumii was recorded by X-ray examination, and laryngeal endoscopy evaluated the movement of true and false vocal chords, interstitial volume, movements of epiglottis and arytenoid cartilage, and mucosa. Khuumii increases the workload of the cardiovascular system by 70-80%. Furthermore, the sound frequency is 2-4 times higher than that of normal speech, and sound volume is 0.5-1 times higher. 95.3% of throat singers did not have a sore throat, 88.4% did not experience heavy breathing, and 74.1% had no hoarseness. During the formation of khuumii sound, thoracic cavity, diaphragm, and lungs regulate the intensity of the air reaching the vocal folds, exert pressure on the airways and vibrate the sound waves through air flows passing through the larynx and vocal folds. Mouth-nose cavity as well as pharynx are responsible for echoing the sound. Conclusion It is appropriate to divide khuumii into two main types according to structural and functional changes in the organs involved; shakhaa and kharkhiraa. Khuumii, the “Human music” originating from the people of Altai Khangai basin by imitating the sounds of nature with their own voice in ancient times, spread all over the world from Mongolia and it is proposed to classify khuumii into two main types of shakhaa and kharkhiraa in terms of structural involvement and functionality.