Tongue Anatomy

Tongue Anatomy

All about Tongue Anatomy

tongue anatomy and morphology

Introduction

The tongue is a muscular organ situated in the floor of the mouth

Parts of Tongue

  1. Root
    • Root is attached to the styloid process and soft palate above, and to mandible and the hyoid bone (lingual bone or tongue-bone) below
    • Tongue cannot be swallowed due to these attachments, related to geniohyoid and mylohyoid attachments
  2. Tip: Tip of tongue forms the anterior free end, which lies behind the upper incisor teeth at rest position
  3. Dorsum / Body: It is convex in all directions and divided into following 3 parts
    • Oral or Papillary part of the tongue
      • It is the anterior 2/3rd part of tongue
      • It is placed on the floor of the mouth
      • It's margins are free and in contact with gums and teeth
      • In front of palatoglossal arch it's both margins shows 4 to 5 vertical folds named Foliate Papillae
      • Superior surface shows a median furrow and covered with papillae which makes it rough
      • Inferior surface shows a median fold called Frenulum Linguae, covered by a smooth mucous membrane
      • On either side of frenulum there is a prominence produced by the deep lingual vein and laterally there is a fold called Plica Fimbriata
    • Pharyngeal / Lymphoid part of the Tongue
      • It lies behind palatoglossal arch and sulcus terminalis
      • It's posterior part is called base of the tongue, which forms the anterior wall of oropharynx
      • It's mucous membrane has no papillae, but it has many lymphoid follicles that collectively constitutes the lingual tonsil
    • Posterior most part of the Tongue
      • It is connected to the epiglottis by 3 folds of mucous membrane, which are median glossoepiglottic fold and the right and left lateral glossoepiglottic fold
      • On either side of median fold, there is depression called Vallecula
      • Lateral folds separates the vallecula from the piriform fossa

Clinical Anatomy of Tongue

  1. Glossitis: Inflammation of tongue, which is a part of generalized oral cavity ulceration or stomatitis
  2. Atrophy of filliform papillae: Tongue becomes smooth in certain anaemias
  3. Acute Glossitis: Presence of rich lymphatics network and loose areolar tissue is responsible for enormous swelling of the tongue
  4. Undersurface of tongue is good site to diagnose Jaundice
  5. In unconscious patients, tongue may fall back and obstruct the air passage which can be prevented by lying the patient on one side with head down or keeping the tongue out mechanically

Papillae of Tongue

Tongue Papillae are the projections of mucous membrane or corium which gives the roughness to anterior 2/3rd of tongue

  1. Circumvallate / Vallate Papillae
    • Largest size of all papillae, with 1 - 2 mm in diameter
    • 8 - 12 in number
    • Situated immediately anterior to the sulcus terminalis
    • Each papilla is a cylindrical projection surrounded by a circular sulcus
    • The wall of papillae has taste buds
  2. Fungiform Papillae
    • These are numerous at tip and margins of the tongue, sometimes also seen in dorsum of tongue
    • Smaller than circumvallate papillae but larger than filliform papillae
    • Each papilla contains narrow pedicle and a large rounded head
    • They have bright red colour
  3. Filliform / Conical Papillae
    • Covers the presulcular area of dorsum of the tongue, giving it's characteristic Velvety appearance
    • Smallest and most numerous of the lingual papillae
    • Each papillae is pointed and covered with keratin
  4. Folliate Papillae: 4 to 5 vertical folds at lingual margin

Muscles of Tongue

Middle fibrous septum divides the tongue into left and right halves, each half contain 4 Intrinsic and 4 Extrinsic muscles as follows:

  1. Intrinsic Muscles
    • Superior Longitudinal
    • Inferior Longitudinal
    • Transverse
    • Vertical
  2. Extrinsic Muscles
    • Genioglossus
    • Hyoglossus (often including the Chondroglossus)
    • Styloglossus
    • Palatoglossus

Arterial Supply of Tongue

  1. It is derived from the tortuous Lingual Artery, branch of the External Carotid Artery
  2. Root of tongue is supplied by Tonsillar Artery, branch of Facial Artery and Ascending Pharyngeal branch of External Carotid Artery

Venous Drainage of Tongue

  1. Deep lingual vein is largest and main vein of tongue
  2. It unites the Lingual vein which ends in the Internal Jugular Vein

Lymphatic Drainage of Tongue

  1. Tip of tongue bilaterally drains to Submental lymph node
  2. Anterior 2/3rd of tongue drains to Submandibular lymph node
  3. Posterior 1/3rd and posterior most part drains to upper deep cervical and jugulodigastric lymph node
  4. Whole lymph finally drains to Jugulo-omohyoid lymph node; known as Lymph Node of Tongue

Nerve Supply of Tongue

  1. Motor Nerve: All the intrinsic and extrinsic muscles are supplied by the Hypoglossal nerve except Palatoglossus which is supplied by Cranial root of the accessory nerve through the Pharyngeal nerve plexus
  2. Sensory Nerve:
    • Anterior 2/3rd of tongue: Lingual nerve for general sensation and Chorda tympani for taste sensation, except circumvallate papillae
    • Posterior 1/3rd of tongue: Glossopharyngeal nerve for both general sensation and for taste sensation, including circumvallate papillae
    • Posteriormost of tongue: Vagus nerve through internal laryngeal branch

Histology of Tongue

  1. Bulk of the tongue is made up of striated muscles
  2. Mucous membrane consist of layer of connective tissue, lined by stratified squamous epithelium. On oral part of dorsum it is thin, forms papillae and adherent to the muscles. On pharyngeal part of dorsum, it is very rich in lymphoid follicles. Numerous mucous and serous gland lies deep to the mucous membrane
  3. Taste buds are most numerous on the sides of circumvallate papillae and walls of surrounding sulci. Taste buds are numerous over the foliate papillae and posterior 1/3rd of tongue, whereas sparsely distributed on the fungiform papillae, soft palate, epiglottis and pharynx. There are no taste buds on mid dorsal region of oral part of tongue

Development of Tongue

  1. Epithelium
    • Anterior 2/3rd: First 2 lingual swellings arises from 1st branchial arch
    • Posterior 1/3rd: 3rd branchial arch
    • Posterior most: 4th branchial arch
  2. Muscle: Occipital myotomes
  3. Connective tissue: Local mesenchyme

Taste Pathway of Tongue

  1. Taste from anterior 2/3rd of tongue except circumvallate papillae is carried by Chorda tympani till the geniculate ganglion. The central process go to the tractus solitarius in the medulla
  2. Taste from posterior 1/3rd of tongue including circumvallate papillae is carried by Glossopharyngeal nerve till the inferior ganglion. The central processes also reach the tractus solitarius
  3. Taste from the posterior most part of the tongue and epiglottis is carried by Vagus nerve till inferior ganglion. These central processes also reach tractus solitarius
  4. After a relay in tractus solitarius, the solitario-thalamic tract is formed which becomes a part of trigeminal lemniscus and reaches postero-ventromedial nucleus of thalamus of the opposite side. Another relay here takes them to lowest part of post central gyrus, which is the area for taste