Tongue

The tongue is a complex, principally muscular, structure that extends from the oral cavity to the oropharynx. It has important roles in speech, swallowing and taste. 

Gross anatomy

The tongue has a tip, dorsum, inferior surface and root. The tongue is made of a midline lingual septum and hyoglossus membrane, and multiple muscles ^1,2,4. The muscles are divided into intrinsic and extrinsic muscle groups:

• intrinsic muscles of the tongue which do not have attachments outside the tongue and whose action is to alter the shape of the tongue:
  • superior longitudinal muscle of the tongue
  • inferior longitudinal muscle of the tongue
  • transverse muscle of the tongue
  • vertical muscle of the tongue
• extrinsic muscles of the tongue (mnemonic) which have attachments outside the tongue and therefore their actions alter the positionof the tongue:
  • genioglossus muscle
  • hyoglossus muscle
  • styloglossus muscle
  • palatoglossus muscle

The tongue is divided into two parts at the level of the circumvallate papillae ^1,3:

• mobile tongue: anterior two-thirds; part of the oral cavity
  • includes root of tongue, which is considered separately due to its importance in oropharyngeal cancer
• base of tongue: posterior one-third; fixed; part of the oropharynx

The tongue is covered by a mucosa, which is roughened on the dorsal surface covered by filiform, fungiform and circumvallate papillae. Posteriorly, the base of the tongue contains the lingual tonsils ⁴.  

On its inferior surface the tongue is usually joined to the floor of the mouth by a thin midline membrane, the frenulum of the tongue.

Arterial supply

• lingual artery (principally) but also branches from the facial and ascending pharyngeal arteries ⁴

Venous drainage

• follows arterial supply draining to the lingual, facial and/or internal jugular veins ⁴

Innervation

• hypoglossal nerve (CN XII): intrinsic and extrinsic muscles (except palatoglossus muscle, which is supplied by the pharyngeal plexus)
• lingual nerve
  • sensory supply to the anterior two-thirds
  • special sensory (taste) fibres diverge from the lingual nerve and travel with the facial nerve (CN VII) via chorda tympani
• glossopharyngeal nerve (CN IX): sensory supply to posterior one-third ²

Lymphatic drainage

The dorsal mucosal surface of the pharyngeal part of the tongue contains groups of lymphoid follicles forming the lingual tonsils. 

The anterior tongue drains to several nodal groups:

• apex: drains to submental and submandibular nodes
• body: drains to submandibular nodes then to the deep cervical nodes (especially the jugulodigastric and jugulo­omohyoid nodes)

The posterior tongue drains directly to deep cervical nodes.

Of clinical significance in tumours approaching the midline, central regions of the tongue may drain bilaterally, especially if lymphatic vessels on one side are obstructed.

History and etymology

The word tongue is derived from an Old English word tunge, meaning the organ of phonation, or speech itself, and ultimately is thought to be derived from lingua, the Latin for tongue ⁷.

Related pathology

• neoplastic
  • squamous cell carcinoma of the tongue
  • haemangioma
  • lipoma
• non neoplastic
  • neck tongue syndrome
  • ankyloglossia (tongue tie)
  • macroglossia