Normal Anatomy of the Esophagus The esophagus is a muscular tubular structure that measures approximately 25 cm in adult individuals and extends from the cricopharyngeal muscle, which forms the upper esophageal sphincter (at the level of the sixth cervical vertebra, about…
Generalities The mediastinum is the portion of the thoracic cavity located between the pleural cavities, extending anteroposteriorly from the sternum to the spine and from the thoracic inlet superiorly to the diaphragm inferiorly. The numerous organs and structures it contains…
Normal Anatomy of the Pleura Both the visceral and parietal pleural layers have a lining of mesothelial cells endowed with a continuous basement membrane and resting on a layer of well-vascularized fibroelastic connective tissue matrix. The submesothelial connective tissue is…
Normal Anatomy Grossly the lungs are subdivided into lobes, three on the right (upper, middle, and lower) and two on the left (upper and lower). Each lobe is supplied by a dedicated lobar bronchus with a companion artery and vein…
Normal Gross Anatomy and Embryology The parathyroid glands, the last major organ to be recognized in humans, were discovered in 1880 by Ivar Sandstrom, a Swedish medical student, as recounted by Aidan Carney in his delightful essay on the subject.…
Normal Anatomy and Thyroid Gland Development The thyroid anlage appears in the embryo as a midline structure at the site corresponding to the foramen cecum of the adult tongue. From here, it descends as a component of the thyroglossal duct…
Introduction Nearly all the diseases that can involve the ear also occur in other sites of the body. However, some of these diseases either have a predilection for the ear or pose special problems when occurring at this site. Only…
Normal Anatomy The major salivary glands are the paired parotid, submandibular (submaxillary), and sublingual glands. The parotid gland weighs 14–28 g, the submandibular gland weighs 7–8 g, and the sublingual gland weighs 3 g. The main duct of the parotid gland (Stensen duct)…
Normal Anatomy In most respects, the microscopic features of the mandible and maxilla differ in no significant way from those of any other bones. Their peculiarity is derived from their close proximity to the mucosal surface of the oral cavity…
Oral Cavity and Oropharynx Normal Anatomy The oral cavity and oropharyngeal region represent the upper portion of the digestive tract; in addition, the oropharynx constitutes a portion of the upper respiratory tract. The oropharynx and hypopharynx share many of the…