International Journal of Science and Healthcare Research Vol.5; Issue: 2; April-June 2020 Website: ijshr.com Case Report ISSN: 2455-7587 International Journal of Science and Healthcare Research (www.ijshr.com) 73 Vol.5; Issue: 2; April-June 2020 Abnormal Passage of Oesophagus through the Diaphragm - A Case Report Dasari Chandi Priya 1 , Mrudula Chandrupatla 2 , N. Archana 1 1 Assistant Professor, 2 Professor and HOD, Department of Anatomy, Apollo Institute of Medical Sciences and Research, Hyderabad, Telangana, India, 500090. Corresponding Author: Dasari Chandi Priya ABSTRACT Diaphragm is a musculo-aponeurotic sheet separating thoracic and abdominal cavities. It has few apertures in it providing passage for structures traversing between both the cavities. Out of those, oesophageal hiatus (OH) has got more surgical importance as it goes through muscular portion of diaphragm and is prone to changes in hiatal diameter due to excursions of diaphragm. This should lead to stomach herniation into thoracic cavity and acid reflux with inspiration but it is prevented by the arrangement of crural diaphragm around the OH and angle at the entry of oesophagus into stomach as studied by Collis et al. However, due to age or congenital defects, above mentioned pathologies do occur. This has led to pronounced research into normal anatomy of OH and most of the studies have found that right crus provides significant contribution to OH margins. During cadaveric dissection at our college in the department of Anatomy, we have a found OH, in a cadaver, bounded by the crura on both sides and median arcuate ligament anteriorly. Aorta and other routinely found structures are seen passing through the same hiatus posterior to the oesophagus. Precise knowledge about oesophageal hiatus is essential for better understanding of physiological and clinical phenomena. Key words: Diaphragm openings, Oesophageal hiatus, Crura, Median arcuate ligament. INTRODUCTION Diaphragm is a dome shaped, musculofibrous sheet separating the thoracic cavity from the abdominal cavity. Its convex superior surface faces thoracic cavity and concave inferior surface faces abdominal cavity. The muscular component of diaphragm arises from the circumference of thoracic outlet and it has 3 components i.e. sternal, costal and lumbar. Sternal fibres arise from the posterior aspect of xiphoid process and costal fibres from the inner surface of lower six costal cartilage and ribs, interdigitating with transversus abdominis. The lumbar part arises from medial and lateral arcuate ligaments, which extend across psoas major and quadrates lumborum muscles, and also from the right and left crura. The right crus arises the anterolateral surfaces of the bodies and intervertebral discs of the upper three lumbar vertebrae. The left crus arises from the corresponding parts of the upper two lumbar vertebrae. The medial tendinous margins of the crura meet in the midline to form an often poorly defined arch, the median arcuate ligament. All these fibres insert into central tendon. Many structures pass between the abdominal and thoracic cavities through the openings in the diaphragm. However there are mainly three openings for the passage of inferior vena cava, esophagus and aorta. Caval opening, quadrilateral in shape, lies at the level of intervertebral disc between 8 th and 9 th thoracic vertebrae and passes through the central tendon of diaphragm. It conveys IVC, which adheres to the margins of opening, and right phrenic nerve. Aortic opening is seen at the level of 12 th thoracic vertebra, conveying aorta, thoracic duct,