Preface

The pharynx is an incredible structure in the human body. The pharynx is a conical passage connecting the oral cavity and nasal cavity to the junction of the esophagus and trachea. There is also another passage called the eustachian or pharyngotympanic tube, which links the nasopharynx to the middle ear.

The pharynx moves food or water from the mouth to the esophagus and moves air from the nasal and oral cavities to the larynx. The larynx, the nearby structure, is a triangle-shaped box that consists largely of cartilages with surrounding structures, including muscles, fibers, and elastic tissue components. They play important roles in swallowing, breathing, producing sound, and protecting the trachea against food aspiration. During the normal speech, air comes from the lungs and sound comes from the vocal cords and then travels upward in the pharynx. In other words, the pharynx is a dynamic rendezvous site of gases (air), liquids (water), and solids (food).

Although the pharynx is relatively small compared to other organ systems, it is just as vital. For example, obstructive sleep apnea, the most common sleep-related breathing disorder, is characterized by repetitive collapse and closing of the pharynx during sleep. The most common cause of sleep apnea in children is enlarged tonsils and adenoids that block the airway and obstruct breathing during sleep. In addition, there are some conditions that can cause the pharynx to not function properly, affecting digestion, respiration, phonation, or sleep.

The pharynx is a crossroad in the upper part of the digestive and respiratory pathways and malignancy at this level leads to the impairment of vital functions, such as breathing, feeding, and speech. Pharyngeal cancer is one of the most challenging cancers in terms of location, evolution, prognosis, and functional implications. With advances in treatment, surgery and reconstruction techniques can deliver an adequate quality of life for patients. Pharyngeal reconstruction is a complex and difficult process that should involve a combined evaluation of the size and location of the defect, the patient's age and comorbid status, and the simplest reconstruction with the greatest level of function.

Based on these concepts, the book highlights developments as well as future perspectives in the ever-expanding field of pharynx health. It is a great reference for otolaryngologists, pulmonologists, gastroenterologists, pediatricians, neurologists, and other medical professionals.

I am grateful to everyone who has contributed to the editorial process of this book, including the wonderful staff at IntechOpen. This book would not be possible without their help and support. I would also like to express my gratitude to my family, teachers, and colleagues.

#### **Tang-Chuan Wang**

Chairman of Otolaryngology-Head and Neck Surgery, China Medical University Hsinchu Hospital, Taiwan

> School of Medicine, College of Medicine, China Medical University, Taiwan

> > Section 1

Introduction - The Incredible

Pharynx Affecting Human

Life

Department of Biomedical Engineering, College of Biomedical Engineering, China Medical University, Taiwan

Research Scholar of Harvard Medical School, MA, USA

Research Scholar of University of Iowa Hospitals and Clinics, IA, USA

Member of American Academy of Otolaryngology-Head and Neck Surgery

Fellow of the American College of Surgeons

## Section 1
