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Body Surface

The primary surface landmarks of the oral cavity and larynx are associated with the mouth (philtrum, vermillion border, oral fissure and angle of the mouth [buccal angle]) and larynx (hyoid, thyroid prominence and cricoid arch). Branches of the maxillary (infraorbital) and mandibular (buccal and mental) divisions of the trigeminal nerve and cervical plexus (great auricular and transverse cervical) innervate the skin overlying the oral cavity and larynx.

Skeleton and Joints

The bones and cartilages associated with the oral cavity, pharynx and larynx are the mandible, maxilla, palatine and hyoid bones, and epiglottal, thyroid, cricoid, arytenoid, corniculate and cuneiform cartilages. There are synovial joints between the inferior cornua of the thryroid cartilage and the lamina of the cricoid cartilage.

Organization

This region of the head and neck includes the oral cavity, palate, pharynx and larynx. The oral cavity extends from the lips to the oropharyngeal isthmus (at the palatoglossal arch). It is subdivided into the vestibule and the oral cavity proper. The vestibule is the space between the lips and cheeks, and the teeth and gingivae. The roof is the hard palate and the floor is the mylohyoid muscle. The anterior 2/3rds of the tongue and sublingual gland occupy the oral cavity.

The pharynx is the half-funnel shaped musculomembranous tube positioned posterior to the nasal cavity, oral cavity and larynx. It is subdivided into three regions. The nasopharynxis is superior to the soft palate and is continuous with the nasal cavity through the posterior nares (choanae). The pharyngotympanic tubes open into the nasopharynx. The oropharynx is continuous with the oral cavity through the oropharyngeal isthmus and extends from the soft palate to the epiglottis. The soft palate is the musculofibrous structure extending posterior to the hard palate that closes off the oropharynx from the nasopharynx during swallowing. The palatine tonsil is located in the lateral wall of the oropharynx, anterior to the palatopharyngeal arch. The laryngopharynx (hypopharynx) extends from the epiglottis at the lateral glossoepiglottic folds to the pharyngo-esophageal junction at the posterior border of the cricoid cartilage.

The larynx, positioned inferior to the hyoid and continuous with the trachea, is comprised of cartilages, ligaments, membranes, muscles and a lining mucous membrane. It functions during respiration, vocalization and swallowing. The laryngeal space is subdivided into a vestibule between the epiglottis and vocal folds and the infraglottic cavity inferior to the vocal folds. The vocal folds extend from the arytenoid cartilages to the posterior aspect of the thyroid angle (where the two laminae meet). Vestibular (false vocal) folds are present immediately superior to the vocal folds.

Muscles

Muscles of the oral cavity function to elevate the hyoid (geniohyoid and mylohyoid), and protrude (genioglossus), retract (styloglossus), flatten (hyoglossus) or change the shape (intrinsics) of the tongue. Muscles of the palate function to elevate (levator veli palatini) or tense (tensor veli palatini) the soft palate, and approximate (palatoglossus) the palatoglossal folds. Muscles of the pharynx function to elevate (palatopharyngeus and stylopharyngeus) or constrict (peristalisis; superior, middle and inferior constrictors) the pharyngeal wall. Muscles of the larynx function to abduct (posterior cricoarytenoid), adduct (lateral cricoarytenoid, interarytenoids), tense (cricothyroid) or slacken (thyroarytenoid) the vocal folds during vocalization, and close (aryepiglotticus) the laryngeal inlet during swallowing.

Innervation

Branches of the maxillary, mandibular and facial nerves innervate (sensory, taste, postganglionic sympathetic and postganglionic parasympathetic) the oral cavity. Branches of the maxillary, glossopharyngeal and vagus nerves innervate (sensory, taste, postganglionic sympathetic and preganglionic parasympathetic) the pharynx. Branches of the vagus nerve innervate (sensory, postganglionic and preganglionic parasympathetic) the larynx. Muscles of the tongue are innervated by the hypoglossal and mandibular (sensory) nerves, by the mandibular and vagus nerves, the pharynx by the glossopharyngeal and vagus nerves and larynx by the vagus nerve. The submandibular and sublingual glands are innervated by postganglionic sympathetic axons from the superior cervical ganglion and postganglionic parasympathetic axons from the submandibular ganglion.

Blood Supply

Branches of the lingual and maxillary arteries are the primary blood supply of the oral cavity. Branches of the facial and maxillary arteries are the primary blood supply of the soft palate. Branches of the ascending pharyngeal artery are the primary blood supply of the pharynx. Branches of the superior and inferior thyroid arteries are the primary blood supply of the larynx. Tributeries of the corresponding veins drain the oral cavity, soft palate, pharynx and larynx.