Oral Cavity Proper (Palate & Tongue) - Oral Cavity Anatomy

The video introduces the oral cavity proper, building on the previous discussion of the oral vestibule. It outlines the borders of the oral cavity proper: anteriorly and laterally by the alveolar processes, gums, and teeth; superiorly by the hard and soft palate; and inferiorly by the floor of the oral cavity and the tongue. Posteriorly, it connects to the pharynx through the oropharyngeal isthmus.

The palate forms the superior border, separating the oral cavity from the nasal cavity. The hard palate is the bony anterior part, composed of maxillary alveolar processes and the horizontal plate of the palatine bone, covered by periosteum and a mucus membrane with palatine glands. Key features include the incisive papilla, palatine raphe, and transverse palatine folds. The soft palate, or velum palatinum, is the posterior, flappy part made of mucosal membrane, muscles, palatine aponeurosis, vasculature, and mucous glands. The uvula is the free end of the soft palate.

The soft palate is crucial for swallowing. Its primary role is to block off the nasal cavity during swallowing, preventing food from entering the nasopharynx. Along with the tongue blocking the oral cavity and the epiglottis blocking the larynx, this ensures food travels only down the esophagus.

Five muscles attach to the soft palate: the muscle of the Uvula (shortens and elevates the uvula), Levator Veli Palatini (elevates the soft palate and opens the auditory tube), Tensor Veli Palatini (tenses the soft palate and widens the auditory tube), Palatoglossus (elevates the tongue root, depresses the soft palate, narrows the pharynx opening), and Palatopharyngeus (elevates the pharynx, depresses the soft palate, narrows the pharynx opening). The palatoglossus and palatopharyngeus muscles form arches that house the palatine tonsils.

The inferior border comprises the floor of the oral cavity and the tongue. The floor is made up of the mylohyoid, anterior belly of digastric, and geniohyoid muscles. Salivary glands (submandibular and sublingual) are also located here. The tongue is a muscular organ with an apex, body, and root.

The tongue has several landmarks: the median sulcus, the V-shaped terminal sulcus separating the body from the root, and the foramen caecum (a remnant of the thyroglossal duct). The lingual tonsil is located at the root. Mucosal folds like the glossoepiglottic folds and the median epiglottic fold connect the tongue to the epiglottis, forming the epiglottic vallecula. The frenulum connects the tongue to the oral cavity floor, flanked by fimbriated folds, sublingual folds, and sublingual caruncles for salivary gland openings.

Tongue muscles are divided into extrinsic (originate from bone, insert into tongue, focus on movement) and intrinsic (originate and insert within the tongue, focus on changing shape). Extrinsic muscles include Genioglossus (pulls tongue forward/depresses), Styloglossus (pulls tongue backward/elevates), Hyoglossus (pulls tongue backward/depresses), and Palatoglossus (elevates tongue root, depresses soft palate). Intrinsic muscles are the Superior/Inferior longitudinal (shorten tongue), Vertical (flatten tongue), and Transverse (narrow tongue) muscles.

The surface of the tongue is covered with lingual papillae, which contain taste buds. These include Filiform papillae (for roughness), Fungiform papillae (with taste receptors), Vallate papillae (near the terminal sulcus, with taste buds), and Foliate papillae (at the lateral regions, with taste buds).

Posterior to the oral cavity proper is the oropharynx, separated by the isthmus of fauces (or oropharyngeal isthmus), which marks the border between the pharynx and the oral cavity.