oordinated in the brainstem, but has some voluntary control. The larynx is suspended from the hyoid by the thyrohyoid ligament and thyrohyoid muscle.
The roof of the mouth is formed by the hard palate (maxilla), the soft palate (velum), and the uvula (17). The pharynx consists of three constrictor muscles and the pharyngeal walls. Spaces between the inferior constrictor muscle and the thyroid cartilage form the pyriform sinuses. The pharynx opens into the larynx at the base of the tongue (20). The epiglottis attached to the hyoid bone rests against the base of the tongue. The aryepiglottic folds form the lateral walls of the laryngeal vestibule. The arytenoids tilt anteriorly during swallowing closing the airway entrance. The larynx and trachea are suspended between the hyoid bone and the sternum by the laryngeal strap muscles. The cricopharyngeal muscle fibers and the cricoid lamina form the upper esophageal sphincter, preventing backflow from the esophagus into the larynx. The esophagus is a muscular tube, with the lower esophageal sphincter at the bottom end to prevent reflux of stomach contents, including stomach acid. It passes through the neck, chest, and diaphragm and attaches to the stomach. The posterior wall of the trachea is shared in common with the anterior wall of the esophagus.
A. Oral Cavity: The oral cavity represents the horizontal subsystem of the mastication and deglutition system involved in swallowing (Kennedy and Kent, 1985). It is known as the stomato-gnathic system (stomato = mouth, gnathic = the jaw). It includes the maxilla, mandible, dentition with supporting structures, hyoid bone, temporomandibular joint, mastication and facial expression muscles, tongue, salivary glands, neurovascular and lymphatic glands ligaments, skin, and mucous membranes.
Initial decomposition of food prior to swallowing is achieved by the masticatory function of the teeth and the maxilla and mandible ...