Anatomy of the Oral Region and Cavity

Oral Region

• The oral region encompasses the oral cavity, teeth, gingivae, tongue, palate, and the palatine tonsils.
• The oral cavity is the initial site for food ingestion and preparation for digestion in the stomach and small intestine.
• Swallowing (deglutition) begins voluntarily in the oral cavity.
• The voluntary phase pushes the bolus from the oral cavity into the pharynx, initiating the automatic swallowing phase.

Oral Cavity

• The oral cavity comprises two parts: the oral vestibule and the oral cavity proper.
• The oral cavity proper is the space between the upper and lower dental arches (maxillary and mandibular alveolar arches).
• The oral cavity proper has boundaries defined by the alveolar arches and teeth.
• The palate forms the roof of the oral cavity.
• The oral cavity connects to the oropharynx.
• When the mouth is closed, the oral cavity is filled by the tongue.

Tongue

• The tongue (lingua/glossa) exhibits diverse shapes and positions.
• The tongue is partially within the oral cavity and the oropharynx.
• The tongue plays a role in mastication, taste, deglutition, articulation, and oral cleansing, but its primary functions involve speech and moving food into the oropharynx.
• The tongue has a root, body, apex, dorsal (superior) surface, and inferior surface.
• The root is the posterior third of the tongue.
• The body is the middle portion (anterior two-thirds).
• The apex, or tip, is at the anterior end of the body.
• The tongue is composed of intrinsic and extrinsic muscles, enabling versatile movements.
• The tongue's surface is studded with four types of papillae: vallate, foliate, filiform, and fungiform.
• Taste buds are located in many papillae, providing sensation.

Muscles of the Tongue

• The tongue's intrinsic muscles alter its shape.
• The tongue's extrinsic muscles control its position.
• Four intrinsic muscles and four extrinsic muscles are present in each half of the tongue.

Innervation of the Tongue

• All tongue muscles, except the palatoglossus, are innervated by the hypoglossal nerve (CN XII).
• The palatoglossus muscle receives innervation from the vagus nerve (CN X).
• The anterior two-thirds of the tongue's mucosa receives general sensation from the lingual nerve, a branch of the trigeminal nerve (CN V3).
• The posterior third of the tongue's mucosa and the vallate papillae use specific sensation through the glossopharyngeal nerve (CN IX).
• The anterior two-thirds of the tongue's taste is transmitted via the chorda tympani, a branch of the facial nerve (CN VII).

Taste Anatomy

• The four fundamental tastes are sweet, salty, sour, and bitter.
• Different taste sensations are perceived in different locations on the tongue.

Vasculature of the Tongue

• Arteries of the tongue are derived from the lingual artery, branching from the external carotid artery.
• Deep lingual arteries supply the anterior tongue region.
• Dorsal lingual arteries supply the posterior tongue region.
• Veins accompanying the lingual arteries drain into the sublingual veins.
• In older individuals, sublingual veins may exhibit varicosity (enlargement).
• Both veins and arteries empty into the internal jugular vein.

Lymphatic Drainage of the Tongue

• Most lymphatic drainage aligns with venous drainage.
• Lymph from the tongue's posterior third drains to superior deep cervical lymph nodes.
• Lymph from the medial section of the anterior two-thirds drains to inferior deep cervical lymph nodes.
• Lateral parts of the anterior two-thirds drain to submandibular lymph nodes.
• The apex and frenulum of the tongue drain to submental lymph nodes.

Gag Reflex

• The anterior section of the tongue is not usually associated with the gag reflex.
• However, stimulation of the posterior tongue triggers a gag reflex, mediated by the glossopharyngeal (CN IX) and vagus (CN X) nerves.

Paralysis of the Genioglossus

• Paralysis of the genioglossus muscle causes the tongue to sag posteriorly.
• This can obstruct the airway, posing a choking risk.
• Relaxing the genioglossus muscles occurs when under general anesthesia.

Injury to the Hypoglossal Nerve

• Injuries to the hypoglossal nerve (CN XII), often due to mandibular trauma, cause paralysis on one side of the tongue.
• The tongue deviates towards the paralyzed side during movement.

Sublingual Absorption of Drugs

• Drugs placed under the tongue are quickly absorbed through the deep lingual veins.

Groove of the Tongue

• A groove separates the tongue into symmetrical halves, indicating areas of fusion during embryonic development.

Explore the fundamental anatomy of the oral region, including the oral cavity, teeth, tongue, and palate. Understand the processes involved in swallowing and the distinct components of the oral cavity. This quiz tests your knowledge of the structures and functions related to oral health and anatomy.