Anatomy of Tongue in a nutshell

Anatomy of Tongue

2 primary functions of the tongue:

1. Digestion:
   • Mechanical digestion- keeps food between the teeth
   • Very important in moving the bolus into the oropharynx
2. Speech formation:
   • All sounds are made by distinct conformations of the tongue
   • Tongue paralysis will lead to major impairment in speech

3 parts of the tongue:

1. Body: called the oral portion, the anterior 2/3 (Infront of the terminal sulcus).
   • Is the freely movable portion
   • Moves bolus, forms sounds etc.
2. Root: called the pharyngeal portion, the posterior 1/3 (Behind of the terminal sulcus).
   • Is fixed and doesn’t move
   • Faces the oropharynx
3. Apex/tip: pointed portion most forward in the mouth.

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1 – rima glottidis; 2 – incisure interarythonoidea; 3 – tuberculum corniculatum; 4 – tuberculum cuneiforme; 5 – plica aryepiglottica; 6 – recessus piriformis; 7 – plica glossoepiglottica mediana; 8 – plica glossoepiglottica lateralis; 9 – tonsilla palatina sinistra; 10 – folliculi linguales; 11 – papillae conicae; 14 – sulcus medianus linguae; 15 – apex linguae; 12, 16 – papillae filiformes; 17 – papillae fungiformes; 13, 18, 19 – papillae foliatae; 20 – papillae vallatae, кзади sulcus terminalis; 21 – foramen cecum linguae; 22 – tonsilla palatina dextra; 23 – epiglottis; 24 – cornu majus ossis hyoidei​

Surfaces of the tongue:

• Dorsum of the tongue: the superior surface

1. • Covered with a thick layer of mucous membrane.
   • The membrane on the body of the tongue is covered with finger / thread-like projections called lingual papillae (4 types)
     1. Filiform Papillae
        • Are the most numerous
        • The smallest / thinnest
        • Contain no taste buds
     2. Fungiform Papillae
        • More “club-shaped”
        • Less numerous
        • Contain singular (usually) taste buds
     3. Vallate Papillae
        • 8-12 largest, cylindrical
        • form an inverted V shape.
        • Contain multiple taste buds
     4. Folate Papillae
        • laterally located, are a series of ridges located more posterior on the body
        • Contain taste buds

• • Features on the surface of the tongue

1. 1. 1. Median Lingual Sulcus
         1. Midline furrow/groove = marks the lingual septum (divides in 2 halves0
         2. Where the two lateral lingual swellings came together
      2. Sulcus terminalis
         1. Sulcus just posterior to Vallate papillae
         2. Marks the anterior 2/3 vs. the posterior 1/3 of the tongue where the posterior tongue bud met the two lateral tongue buds.
      3. Forman cecum is the point where the thyroglossal duct was attached to the tongue (thyroid gland began forming to descend from here)

• • Dorsum of  the Root of the tongue:
    1. The surface is irregular (bumpy) and contains no papillae.
    2. The irregular surface is due to lymphoid tissue on the posterior 1/3 of the tongue called the lingual tonsil.
    3. There are taste buds in the mucous membrane on the root, but they are not associated with papillae.
• The inferior surface of the tongue:

1. 1. Attached to the sublingual fossa by the Lingual Frenulum.
   2. If the lingual Frenulum is too short, it will limit the mobility of the tongue, and thus limit speech (may require surgical detachment)
   3. Mucous membrane: On the inferior surface of the tongue is very thin
      • Can see the lingual vein clearly through it
      • Can deliver drugs by putting them into sublingual fossa where it dissolves and is absorbed into lingual vein (faster than digestion)

Sensory Innervation of the mucous membrane of the tongue:

• Anterior 2/3 Innervation from the trigeminal nerve along the lingual branch
  1. cell bodies are in the trigeminal (Semilunar) ganglion
  2. Taste fibers travel along the chorda tympani combines with lingual nerve) which is a branch of the CN VII and has somas in the Geniculate ganglion.
• Posterior 1/3
  1. Sensation: goes along CN IX lingual branch with cell bodies in the superior/inferior glossopharyngeal/petrosal ganglion.
  2. Taste: Glossopharyngeal ganglia carries these as well with the same ganglia.
  3. Glossopharyngeal does get taste information from Vallate papillae (grew over sulcus terminalis)
• Epiglottis area also has taste sensation from the Vagus nerve, the cell bodies are in the superior/inferior vagal ganglia (Jugular ganglia).

1. 1. Side note: nerves going to the mucous membrane contain sensory, parasympathetic, and sympathetic fibers.

Muscles of the tongue:

• Intrinsic muscles of the tongue:

1. 1. The body of the tongue is a thick muscular structure with intrinsic muscles that run longitudinally, horizontally, and vertically.
   2. These make it possible for the tongue to change shape for different sounds.

• All innervated by the Hypoglossal nerve CN XII
• Extrinsic muscles act on the body of the tongue.

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1 – m. longitudinalis inferior; 2 – m. genioglossus; 3 – m. geniohyoideus; 4 – саrtilago thyreoidea; 5 – os hyoideum; 6 – m. hyoglossus; 7 – m. styloglossus

1. 1. Hyoglossus muscle:
      • Origin: Hyoid bone
      • Inserts: lateral aspect of the body of the tongue
      • Action: Depress/draw down the lateral aspect of the tongue (esp. posterior part)
      • Innervated by Hypoglossal CN XII
   2. Styloglossus muscle:
      • Origin: Styloid process
      • Inserts: lateral aspect of the tongue (blends with intrinsic muscles)
      • Action: Retracts tongue and elevates posterior aspect
      • Innervated by CN XII
   3. Genio-Glossus muscle:
      • Origin: Internal aspect of the mandible (Genial Tubercle)
      • Inserts: Fans out into the body of the tongue
      • Action: Protrudes the tongue
      • Innervation: CN XII
      • This is the key muscle used when testing CN XII (ask the patient to stick out tongue)
   4. Palatoglossus:
      • Is the only muscle with “glossus” in it that is not innervated by CN XII.
      • It is innervated by the Vagus
      • Action: elevate the tongue (if the palate were fixed)

• • None of these muscles cross the midline. There is a septum that separates the two portions (sometimes have fat associated with the boundary between).

1. 1. 1. This is how people can split their tongue and use each half as a separate tongue
      2. each half has independent innervation and vascularization
      3. explains why tongue piercing in the midline can be done without damaging nerves/vessels.
      4. if have damage on the left side, the stronger right side will deviate the tongue to the left when sticking out the tongue.

Blood supply of the tongue:

• Lingual artery supplies the tongue

1. 1. Comes off of the external carotid artery
   2. Runs deep into the hyoglossus muscle (this is why we can’t see it in the lab)
   3. The hypoglossal nerve runs on the superficial surface of the hyoglossus muscle.
   4. As the lingual artery approaches the tongue, it branches:
      • Dorsal lingual arteries
      • Are responsible for serving the posterior portion of the tongue.
   5. Lingual artery continues past the sublingual fossa:
      1. Gives off the Sublingual branch to the sublingual fossa
      2. Lingual artery goes into the body of the tongue
   6. Terminates as the deep lingual artery which supplies the anterior portion, up to the tip of.

3D model of the tongue:

Also read:

1. The Tongue @ TeachMeAnatomy
2. The Tongue @ geekymedics
3. Practice Anatomy tests for free!
4. Best Anatomy books for Medical students
5. Best Anatomy websites & journals
6. Anatomy syllabus in (CBME) in India
7. Anatomy syllabus in Russia & Other CIS
8. Anatomy syllabus in China

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