Tongue

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Description

The tongue is a oval shaped, Pink ,Moist ,Solid Conical, muscular organ, which is situated in a hollow cavity of mouth. As seen in the diagram it has various structure around and several attachments. It moves freely from the anterior side which not directly attached to any other structure. Posterior part of the tongue is attached to numerous structures thus why Tongue plays several important roles such as facilitation of gustatory stimuli, facilitates mastication, speech pathway, as it helps with articulation.

Anatomical Relationships

• Anterior and lateral - teeth
• Superior - hard and soft palates
• Inferior - mucosa of the floor of the oral cavity, sublingual salivary glands, posterior wall of oropharynx
• Posterior - epiglottis, pharyngeal inlet
• Lateral - palatoglossal and palatopharyngeal arches

The mylohyoid muscle, which is responsible for raising the body of the tongue in high vowels and velar consonants. The hyoglossus, which pulls it downwards (and slightly backwards). The styloglossus, which pulls the tongue upwards and backwards. The genioglossus, which forms the bulk of the inferior part of the tongue and pulls the body of the tongue forwards.

Muscles

Tongue is made of 2 main types of group of muscles that are Intrinsic group and Extrinsic group of muscles

Total 4 types of Intrinsic muscle

• The superior longitudinal lingual muscle, which shortens the tongue and curls it upward.
• The inferior longitudinal lingual muscle, which shortens the tongue and curls it downward.
• The transverse lingual muscle, which elongates and narrows the tongue.
• The vertical lingual muscle,which flattens the tongue

The extrinsic muscles are

• The genioglossus muscle protrudes the tongue

• The hyoglossus muscle depresses and retracts the tongue
• The styloglossus muscle draws up the sides of the tongue to create a trough for swallowing following adequate mastication. The pair of styloglossus muscles work together on each side to retract the tongue.
• The palatoglossus muscle, which elevates the posterior tongue, closes the oropharyngeal isthmus, aids in the initiation of swallowing, and prevents the spill of saliva from the vestibule into the oropharynx by maintaining the palatoglossal arch.

Function

Tongue plays several roles in taste, speech, swallowing in oral cavity.

1.      Function of Taste(Gustation):  Taste buds situated in the tongue plays role in taste identification. Taste receptors identify taste in 5 category Sweet, Sour, Salty, Bitter, and Umami.

2.      Function of Speech(Phonation): tongues movement against teeth, palate and within oral cavity helps in  productions of speech

3.      Swallowing and food manipulation(Deglutition): food manipulation occurs in oral cavity, tongue presses food against hard palate and enables mastication, forms the food bolus and promotes swallowing.

Nerve

The motor supply of all Intrinsic as well as extrinsic muscles id done by cranial nerve XII (Hypoglossal) except one which is palatoglossus. Palatoglossus is supplied by Cranial nerve X (Vagus)

Sensory supply of tongue

• Taste sensation of anterior two third- chorda tympani (branch of facial nerve), general sensation of the same by lingual nerve(branch of trigeminal nerve)
• Taste sensation and general sensations  of posterior two third is supplied by glosspharangeral nerve
• Perception taste is also partly performed by epiglottis and epiglottic regions. Taste and general sensation is provided by the internal laryngeal branch of vagus nerve.

Blood Supply

Blood supply to the tongue is predominantly from the lingual artery, a branch of the external carotid artery between the superior thyroid artery and the facial artery

Links

In the video entitled Surface anatomy of the tongue (preview) - Human Anatomy and muscles of tongue by Kenhub the overview of Anatomy of tongue is explained. For further understanding of muscles of tongue and movements of tongue this cane be also an helpful watch.