Anatomy of the Tongue

The Oral Cavity

• The oral cavity is the proximal part of the gastrointestinal system and is the entrance to the alimentary tract.
• It is divided into two parts: the vestibule and the oral cavity proper.

The Vestibule

• The vestibule is the space between the lips and cheeks externally and the gums and teeth internally.
• It is lined by a mucous membrane.
• A small papilla on the mucosa opposite the upper 2nd molar tooth marks the opening of the duct of the parotid gland.

The Oral Cavity Proper

• It is a cavity within the alveolar margins of the maxillae and mandible.
• It extends from the lips to the oropharyngeal isthmus, which is the junction of the mouth and pharynx.
• The roof is formed by the hard palate anteriorly and the soft palate posteriorly.
• The floor is formed by the mylohyoid muscle, and the anterior 2/3 of the tongue lies on the floor.
• The lateral wall is formed by the teeth, gums, and alveolar arches of the jaws.

The Tongue

• The tongue is a mobile, muscular organ that lies in the floor of the mouth and the anterior wall of the pharynx.
• It is a mass of skeletal muscle covered by a mucous membrane.
• It is divided into right and left halves by a median fibrous septum.
• It is concerned with taste, chewing, swallowing, and articulation.

The Location of the Tongue

• The tongue lies on the floor of the oral cavity and is partly oral and partly pharyngeal in position.
• The tongue is attached by its muscles to the hyoid bone, mandible, styloid process, soft palate, and pharyngeal wall.
• At rest, it occupies the oral cavity proper.

The Parts of the Tongue

• The anterior 2/3 of the tongue is the oral part, and the posterior 1/3 is the pharyngeal part.
• The tongue consists of the root, body, and tip.

The External Features of the Tongue

• The tongue has two surfaces: dorsal (superior) and ventral (inferior).
• The root of the tongue is attached to the mandible and hyoid bone.
• The body of the tongue is the bulk between the root and tip.
• The tip of the tongue is the anterior free end of the tongue.

The Dorsal Surface of the Tongue

• The dorsum of the tongue is convex in shape.
• It is divided by the V-shaped sulcus terminalis into the anterior 2/3 (oral part) and the posterior 1/3 (pharyngeal part).
• The foramen caecum is located at the apex of the sulcus terminalis.
• The anterior 2/3 of the tongue has papillae, which are extensions of the mucosa.
• There are three common types of papillae: filiform, fungiform, and circumvallate.

The Taste

• The tongue is a specialized organ with collections of taste buds, taste cells, nerves, and blood vessels.
• The afferent nerve fibers connect with taste buds to respond to different chemical stimuli to discriminate taste.

The Muscles of the Tongue

• The tongue has two types of muscles: intrinsic and extrinsic muscles.
• Intrinsic muscles originate and terminate within the tongue.
• Extrinsic muscles originate outside the tongue and enter the tongue.

The Intrinsic Muscles of the Tongue

• They consist of superior longitudinal, inferior longitudinal, transverse, and vertical muscles.
• They alter the shape of the tongue.

The Extrinsic Muscles of the Tongue

• They are four in number: genioglossus, hyoglossus, styloglossus, and palatoglossus.
• They connect the tongue to the styloid process, soft palate, mandible, and hyoid bone.
• They help in the movements of the tongue.

The Movements of the Tongue

• Protrusion: genioglossus on both sides acting together.
• Retraction: styloglossus and hyoglossus on both sides acting together.
• Depression: hyoglossus and genioglossus on both sides acting together.
• Elevation: styloglossus and palatoglossus on both sides acting together.

The Blood Supply of the Tongue

• The lingual artery is the main arterial supply of the tongue.
• The venous drainage of the tongue is through the deep lingual vein.

The Lymphatic Drainage of the Tongue

• The apex, frenulum, and anterior 2/3 of the tongue drain into the submental nodes, inferior deep cervical nodes, and submandibular lymph nodes.
• The posterior 1/3 of the tongue drains into the superior deep cervical nodes.

The Nerve Supply of the Tongue

• The motor supply of the tongue is through the hypoglossal nerve.
• The sensory supply of the tongue is through the lingual nerve, chorda tympani, glossopharyngeal nerve, and internal laryngeal nerve.

The Development of the Tongue

• The tongue develops from the floor of the primitive pharynx in relation to the pharyngeal arches.
• The mucous membrane of the anterior 2/3 of the tongue develops from the fusion of a pair of lingual swellings with the tuberculum impar.
• The mucous membrane of the posterior 1/3 of the tongue develops from the cranial part of the hypobranchial eminence.
• The muscles of the tongue develop from myoblasts that migrate from the occipital myotomes.

Applied Anatomy

• The sublingual administration of drugs is a preferred route in emergency situations.
• The lesion of the hypoglossal nerve results in a protruded tongue deviating toward the side of the lesion.
• Aglossia is the complete absence of the tongue.
• Bifid tongue is the failure of fusion of the lingual swelling.
• Macroglossia is the hypertrophy of the tongue.
• Tongue tie (ankyloglossia) is the shortening of the frenulum linguae.