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, ventral surface, dorsal surface and root. The tongue is made of a midline lingual septum and hypoglossus membrane, and multiple muscles including ^1,2,4. The muscles are divided into intrinsic and extrinsic muscle groups:

• intrinsic muscles of the tongue
  • vertical muscle of which do not have attachments outside the tongue
  and who's 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 position of 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.  

Blood supply

• arterial supply: lingual artery (principally) but also branches from the facial and ascending pharyngeal arteries ⁴
• venous drainage: follows arterial supply draining to the lingul, facial and/or internal jugular veins ⁴

Nerve supply

• 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 two-thirds ²

Related pathology

• squamous cell carcinoma of the tongue