Anatomy of the Head & Neck
Paired organs include the tonsils, parotid glands, other major salivary glands, maxillary and frontal sinuses, and the nasal cavities. Specific sub sites of these organs, which are considered lateral sites, are indicated with an asterisk (*) in the code table above. All other sites are considered single or non-paired organs.
The anatomy of the head and neck is complex because so many different functional structures are located close to each other. Elements of the digestive, respiratory, nervous, and endocrine systems are located sometimes within millimeters of each other. Many structures have a number of names as well. Please review the anatomic diagrams on the following pages for details on organ structures and synonyms for organ names.
The oral cavity extends from the vermilion (red) border of the lips to the junction of the hard and soft palates in the roof of the mouth, and to the circumvallate papillae on the tongue. The oral cavity consists of the lips, commissures, all surfaces (anterior 2/3 or oral, dorsal, ventral, border) of the tongue except the base of tongue, lingual tonsil, gums (alveolar ridge), floor of mouth, hard palate, buccal mucosa, and retromolar trigone.
For purposes of TNM staging, the pharynx includes the following:
Tonsillar fossae, tonsillar pillars (faucial arch), vallecula, lateral and posterior walls of oropharynx, the base of tongue, soft palate, uvula, and branchial cleft as a site of neoplasm.
Anterior, superior, posterior, and lateral walls of nasopharynx.
Pyriform sinus (70% of all hypopharyngeal malignancies), postcricoid region (15%), hypopharyngeal aspect of aryepiglottic fold, posterior wall (15%), and laryngopharynx.
The larynx is comprised of three sub sites or regions. The supraglottis (35% of all laryngeal cancers) consists of the ventricular bands (false cords), arytenoids, ventricles, suprahyoid epiglottis, infrahyoid epiglottis, and laryngeal aspect of the arytenoepiglottic folds. The glottis (65%) consists of the true vocal cords and their anterior and posterior commissures. The subglottis (1%) consists of the subglottic space extending to the first tracheal ring.
The paranasal (or accessory) sinuses include (in order of frequency) the maxillary, ethmoid, sphenoid, and frontal sinuses. The maxillary sinus (antrum of Highmore) is divided into the infrastructure (anterior and inferior portion) and the suprastructure (superior and posterior). The nasal cavity is divided into two chambers by the nasal septum. The nostrils are the external opening, and the choana is the opening into the nasopharynx. All sinuses and the nasal cavity are paired sites.
The major salivary glands are the parotid (accounting for 90% of all salivary gland tumors), submandibular or submaxillary (about 10%), and sublingual glands (1%). Minor salivary glands are located in many oral cavity structures, including the oral mucosa, palate, uvula, posterior tongue, retromolar trigone, paranasal sinuses, pharynx, larynx, peritonsillar area, and floor of mouth.
The thyroid gland consists of two lateral lobes joined by an isthmus. Sometimes a pyramidal lobe is also present, extending upward anterior to the thyroid cartilage.
Waldeyer's ring: the lymphoid tissues that form a ring around the opening of the throat: tonsils laterally, adenoids superiorly, and lingual tonsil at the base. Waldeyer's ring is considered part of the pharynx.
Ohngren's line: imaginary line or plane dividing the upper and lower portions of the maxillary sinus.
Field defect: pre-disposition of mucosa to develop more than one primary tumor; also called regional diathesis.