This paper looks at the anatomy of the swallowing process, dealing with the oral cavity, the pharynx, larynx, and esophagus, and the muscles and nerves which make them function. It then looks at the process of normal swallowing, which includes the oral stage, the pharyngeal stage, and the esophageal stage, and the mechanisms which make it function. Next, it describes the types of problems encountered in dysphagia - abnormal swallowing - and how these can occur at various points in the swallowing process, and how these can be affected by anatomical defects and disease. The conclusion draws together all the material covered in the paper and stresses the necessity of an understanding of the complex swallowing process to diagnose and treat dysphagia.
The anatomic areas involved in swallowing include the oral cavity, the pharynx, the larynx, and the esophagus (Logemann, 1998). The oral cavity includes the lips, hard palate, soft palate, uvula, mandible, floor of the mouth, tongue, and faucial arches (13). The pockets created by the natural juxtaposition of structures are important because in dysphagia they are where food or liquid may collect and remain after swallowing, e.g. between the alveolus and cheek or lip superiorly and inferiorly, between the lips or cheeks and the mandible or maxilla. The floor of the mouth is formed by the mylohyoid, geniohyoid, and digastric muscles, which attach to the mandible in the anterior and the hyoid bone in the posterior (15). The tongue sits on the hyoid bone, which is embedded in its base, and is suspended in the soft tissue of the floor of the mouth by the digastric, stylohyoid, mylohyoid, and geniohyoid muscles. The tongue is composed of muscle fibers, and can be divided into an oral portion (tip, blade, front, center, and back) and a pharyngeal portion (base). The oral tongue is under cortical or voluntary neural control and the pharyngeal portion is under involuntary neural control c...