This section deals with diseases of the head and neck—but not the brain, which is covered in the section on the nervous system (Section XV). The main rationale of including such diverse organs as the oral cavity, salivary glands, ear, nose, pharynx, and larynx in one section is that they are included in the surgical specialty of otolaryngology. Diseases of the teeth (dental pathology, Chapter 31: The Oral Cavity & Salivary Glands) and eyes (ophthalmic pathology, Chapter 33: The Eye) form the rest of this section. The oral cavity, nose, pharynx, and larynx form the common opening of the respiratory and gastrointestinal systems and are often collectively called the upper respiratory tract.
Viral infections of the upper respiratory tract, which include coryza (the common cold) and pharyngotonsillitis, are among the most common infections of humans and are responsible for the loss of many manhours of work throughout the world. The most common neoplasms in this section are squamous carcinomas of the upper respiratory tract (Chapters 31 and 32) and salivary gland neoplasms (Chapter 31: The Oral Cavity & Salivary Glands).