Journal of Clinical and Diagnostic Research. 2022 Jul, Vol-16(7): AC01-AC05 1 1 DOI: 10.7860/JCDR/2022/55145.16574 Original Article Anatomy Section Morphometry of Adult Human Trachea and its Clinical Implications: A Cadaveric Study in Northern India INTRODUCTION The trachea is an unpaired hollow tube that descends as a continuation of the larynx from C6 to the upper border of T5 vertebra where it divides into right and left principal bronchi [1]. There is a wide variation in different dimensions of trachea in same age group as well as in different age groups in both sexes [2-8]. There is wide variation in dimensions of trachea described in different textbooks and by different authors in different journals [1,9]. Gray’s Anatomy by Standring states that adult trachea is 10- 11 cm long, external transverse diameter is 2 cm in adult males and 1.5 cm in adult females, lumen has an average transverse diameter of 12 mm [1]. Schwartz in Text book “Principles of Surgery” stated that range of tracheal length is 10-13 cm, 18-22 semicircular cartilage rings, 2.3 cm transverse diameter and 1.8 cm anteroposterior diameter [9]. Besides anthropometry, knowledge of morphometric variations is essential as it may help the pulmonologists to understand the aetiology of several pulmonary diseases like bronchitis, emphysema, pulmonary fibrosis and tuberculosis [10]. The present study was taken up to measure different dimensions of trachea (length, subcarinal angle, anteroposterior and transverse diameter, height of rings and distance between posterior ends of tracheal rings) which can be helpful in pulmonary physiology and anaesthesiology to conduct some maneuvers like endotracheal intubation, diagnostic and therapeutic bronchoscopic procedures with skill and perfection. Though the study measuring the dimensions of trachea are available form different parts [3-5,7,11] but the studies related to this area are sparse. Hence, present study was conducted to determine the variations in the dimensions of human trachea in the cadavers of age group 20-70 years in Northern India. MATERIALS AND METHODS The present cross-sectional study was done on 40 tracheas obtained from adult human cadavers in the Department of Anatomy, Sri Guru Ram Das Institute of Medical Sciences and Research, Amritsar, Punjab, India, from March 2019 to December 2021. Inclusion criteria: Adult human cadavers aged between 20-70 years were included. Exclusion criteria: Cadavers aged more than 70 years and less than 20 years, mutilated cadavers, cadavers having sternal and tracheal deformities, Human Immunodeficiency Virus (HIV) and Corona positive cadavers were excluded. Sample size: A total of 40 trachea, obtained from adult human cadavers were enrolled for the study by convenience sampling. Cadaver was placed in supine position on dissection table with extended neck. Skin incision was given from symphysis menti to xiphoid process of sternum. Lateral incision was given from symphysis menti along the lower border of mandible and from xiphoid process upwards and laterally along the floor of axilla. After reflecting skin, superficial fascia, deep fascia, muscles (sternohyoid, sternothyroid and sternocleidomastoid), the sternoclavicular joint was disarticulated, sternum was reflected downward after cutting the ribs at the costal cartilages with the bone cutter. Viscera like lungs, heart, thyroid gland were removed along with great vessels, nerves and prevertebral muscles. The trachea was dissected with the larynx and principal bronchi [11]. The measurements were taken as follows: Tracheal length: It was measured with vernier caliper from the lower border of cricoid cartilage to the apex of subcarinal angle where the trachea was bifurcating [Table/Fig-1]. Total number of tracheal rings were measured in the mid- sagittal line. STUTI MAHAJAN 1 , ANUPAMA MAHAJAN 2 , MONIKA LALIT 3 , POONAM VERMA 4 Keywords: Dimensions, Pulmonary fibrosis, Sleep apnoea, Subcarinal angle, Tracheal rings, Variations ABSTRACT Introduction: There is a wide variation in different dimensions of trachea in same age group as well as in different age groups in both sexes. Besides anthropometry, the study of these morphometric variations is of profound clinical importance as it may help the pulmonologists to understand the aetiology of several pulmonary diseases like bronchitis, emphysema, pulmonary fibrosis and tuberculosis. Aim: To determine the variations in the dimensions of human trachea in the cadavers of age group 20-70 years in Northern India. Materials and Methods: This cross-sectional study was conducted in the Department of Anatomy, Sri Guru Ram Das Institute of Medical Sciences and Research, Amritsar, Punjab, India, during March 2019 to December 2021. A total of 40 tracheas were obtained from adult human cadavers which were included in present study by convenience sampling. The trachea was dissected with the larynx and principal bronchi and measurements were taken. Data collected was saved on Microsoft excel and was analysed by calculating percentages, mean and Standard Deviation (SD). Results: Mean length of trachea was 109.25 mm, mean subcarinal angle was 75.45°. Mean anteroposterior diameter, transverse diameter, mean height and distance between posterior ends of rings was 16.70 mm and 18.10 mm, 4.53 mm and 12.15 mm respectively and mean of inter-ring distance between 1 st -2 nd , 5 th - 6 th , 10 th -11 th , 15 th -16 th Tracheal rings was 1.12 mm. Conclusion: The present study revealed a wide variation in different dimensions viz. length, transverse and anteroposterior diameters, mean height, inter-tracheal ring distance and the subcarinal angle. Accurate anatomical knowledge of the variations is essential for understanding the pathophysiology and management of different airway disorders and in reconstructive surgery of tracheobronchial tree.