tongue

TongueDr. Deepak K Gupta

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Muscles of Tongue


Introduction• A muscular structure in the oral cavity, divided

into 2 parts:– Oral: movable part

– Pharyngeal: non-movable part

• Median fibrous septum is thick tissue separating the tongue into halves

• Functions• Mastication

• Taste

• Talking

• Deglutition


Muscles of Tongue

• There are two sets of muscles of tongue– Extrinsic: attached to specific bony sites outside the

tongue, move the tongue as a whole• Genioglossus• Hyoglossus• Styloglossus• Palatoglossus

– Intrinsic: have no attachments to skeletal structures, alter the shape of the tongue• Superior longitudinal muscle• Inferior longitudinal muscle• Transverse muscle• Vertical muscle

• With the exception of the palatoglossus (CN X), this muscles are supplied by the hypoglossal nerve (CN XII)


Muscles of Tongue


Extrinsic Muscles


Extrinsic Muscles: Genioglossus• Origin

– Mandible (superior genial [mental] spine via an intermediate tendon); more posteriorly the twogenioglossi are separated by the lingual septum

• Insertion– Inferior fibers: Hyoid body

(anterosuperior surface)\– Intermediate fibers: Posterior tongue– Superior fibers: Ventral surface of

tongue (mix with intrinsic muscles)

• Nerve Supply: Hypoglossal n. (CN XII)• Action

– Protrusion of the tongue – Makes dorsum concave– Deviation to opposite side


Extrinsic Muscles: Hyoglossus

• Origin: Hyoid bone (greater cornu and anterior body)

• Insertion: Lateral tongue, between styloglossus and inferior longitudinal muscle

• Nerve Supply: Hypoglossal n. (CN XII)

• Action: Depresses the tongue


Extrinsic Muscles: Styloglossus• Origin: Styloid process of temporal bone (anterolateral aspect of apex)

and stylomandibular ligament• Insertion

– Longitudinal part: Dorsolateral tongue (mix with inferior longitudinal muscle)

– Oblique part: Mix with fibers of the hyoglossus

• Nerve Supply: Hypoglossal n. (CN XII)• Action: Superior and posterior movement of the tongue


Extrinsic Muscles: Palatoglossus

• Origin: Palatine aponeurosis (oral surface)

• Insertion: Lateral tongue to dorsum and fibers of the transverse muscle

• Nerve Supply: Vagus n. (CN X) via the pharyngeal plexus

• Action: Elevates the root of the tongue; closes the oropharyngeal isthmus by contracting thepalatoglossal arch


Intrinsic Muscles


Intrinsic Muscles• Superior longitudinal muscle

– Origin• Thin layer of muscle inferior to the dorsal mucosa;

• Fibers run anterolaterally from the epiglottis and median lingual septum

– Action• Shortens tongue

• Makes dorsum concave (pulls apex and lateral margin upward)

• Inferior longitudinal muscle– Origin

• Thin layer of muscle superior to the genioglossus and hyoglossus;

• Fibers run anteriorly from the root to the apex of the tongue

– Action: Shortens tongue; makes dorsum convex (pulls apex down)


Intrinsic Muscles

• Transverse muscle

– Origin: Fibers run laterally from the lingual septum to the lateral tongue

– Action: Narrows tongue; elongates tongue

• Vertical muscle

– Origin: In the anterior tongue, fibers run inferiorly from the dorsum of the tongue to its ventral surface

– Action: Shortens tongue; makes dorsum convex (pulls apex down)


Dorsal Surface of Tongue



• Its divided in 2 parts:

– Oral portion: Occupies tongue’s anterior 2/3

• Covered with keratinized stratified squamous epithelium

– Pharyngeal portion: Occupies tongue’s posterior 1/3

• Covered with nonkeratinized stratified squamous epithelium

• Sulcus terminalis: A V-shaped groove demarcates junction of these 2 parts.

• Foramen cecum: The initial developmental site for the thyroid gland– The initial developmental site for the thyroid gland



• Median sulcus: Fibrous, divides tongue into halves• Lingual tonsils: Large nodules of lymphatic origin,

cover the pharyngeal surface.• Glossoepiglottic folds: Mucous membranes

– Connect the posterior portion of the folds pharyngeal part of the tongue with the epiglottis of the larynx.

• Palatoglossal Arch: Pass from the soft palate to the lateral aspects of the tongue– Also known as the anterior pillar of the fauces

• Glands: Numerous mucous and serous minor salivary gland

• Papillae: its presence makes the dorsal surface of tongue SPECIALISED


Papillae of Tongue


Specialized mucosa of Tongue

• The mucosa of the dorsal surface of the tongue is different than anywhere else in the oral cavity because it has got– Highly extensible lining

– Different types of lingual papillae

• It bears taste buds and therefore have a sensory function

• The mucous membrane of the tongue is composed of two parts, with different embryologic origins• Anterior 2/3: derived from 1st pharyngeal Arch

• Posterior 1/3: derived from 3rd Pharyngeal Archwww.facebook.com/notesdental

Papillae of Tongue

• There are mainly 4 types of papillae on the dorsal surface of tongue

– Circumvallate papillae

– Foliate papillae

– Fungiform Papillar

– Filliform Papillae


Filliform Papillae

• Most numerous papillae of the tongue

• Pointed keratinized projections formed by overlapping sheets of the surface epithelial cells

• Papillae project toward the oropharynx

• Not associated with taste buds• Easily seen without

magnification• Contribute to the rough

surface of the tongue


Fungiform Papillae

• It can also be seen with the naked eye

• Fewer fungiform than filiform papillae

• Scattered over the surface of the tongue.

• Rounded elevations above the surface of the tongue

• About 2 mm in diameter and with a smooth surface

• Contain taste buds on their superior surfaces

• Surface is not keratinizedwww.facebook.com/notesdental

Foliate papillae

• Located in furrows along the posterior sides of the tongue

• Not as prominent in the human tongue as in lower animals

• 4-11 vertical furrows containing the foliate papillae

• May be lined withtaste buds.


Circumvallate papillae

• Located at the junction of the anterior 2/3 and posterior 1/3 of the tongue

• 8 to 12 in number• Larger than the fungiform papillae• Do not project above the surface

of the tongue• Taste buds line the lateral walls of

the papillae• Ducts of the underlying serous

glands open into the trenches surrounding the papillae– function is to flush out these areas

to allow renewal of taste


Pappillae


T.S. Of Taste Bud


Taste Buds• Goblet-shaped clusters of cells that are oriented

at right angles to the surface of the epithelium

• It has a small pore that opens into the oral cavity

• Tasteable substances may contact the the bud cells

• Relatively constant in size: 60 to 80 µm in length and 35 to 45 µm at their maximum diameter

• Surrounded by few flattened epithelial cells

• Neuroepithelial cells: Since these receptors transmit to nerve endings.


Taste Buds• Type I dark cells - 60%

• Type 2 light cells – 30 % – Clear apical ends

– Shorter, less numerous microvilli that terminate in the inner pore

• Type 3 cells - 7% • similar to type 2 cells in appearance

• do not terminate in microvilli, as do types 1 and 2

• have a blunt, rounded tip that ends in the outer taste pore

• Type 4 cells: basal cell located in the base


Ventral Surface of Tongue


Ventral Surface of Tongue• Ventral or undersurface of the tongue is shiny, and blood

vessels are visible• Lingual frenum

– thin sheet of tissue at the midline that attaches the undersurface of the tongue to the floor of the mouth

• Sublingual papilla– A swelling on both sides of the lingual frenulum at the tongue

base– Marks the entrance of saliva from submandibular glands into

the oralbase cavity

• Plica fimbriata: Fimbriated folds, lateral to the lingual frenulum• Deep lingual veins: under the mucosa between the plica fimbriata

and the lingual frenulum


Ventral Surface of Tongue


Nerve Supply of Tongue

• Since tongue has got functions for mastication, deglutition, speech & taste sensation, it has got 3 sensation

• Sensory: its of 2 types– General somatic afferent (GSA): Pain, temperature,

discriminative touch - Trigeminal (via lingual), glossopharyngeal, and vagus (via internal laryngeal)

– Special visceral afferent (SVA):Taste - Facial (via chordatympani), glossopharyngeal, and vagus (via internal laryngeal

• Motor: Hypoglossal n., Pharyngeal plexus, pharyngeal branch of spinal accessory nerve


Nerve supply and developement arch relationship of tongueAnterior 2/3 rd of

tongue

Posterior 1/3 rd of

tongue

Posterior most

portion of tongue

Taste Chorda Tympani Glossopharyngeal Vagus – internal

laryngeal

Sensory Lingual of V3 Glosssopharyngeal Vagus – internal

laryngeal

Motor All extrinsic and intrinsic muscle except palatoglossus –

Hypoglossal N, palatoglossus – cranial root of accessory N

Arch

Developement

First Third Fourth


Vascular Supply• The tongue is supplied by the

– Lingual artery : (from the maxillary artery)• Divides into its terminal branches

– Deep lingual artery

– Sublingual artery

– Submental artery : branch of facial artery from ECA, anastomose with sublingual artery

– Lingual vein: runs parallel to the artery • On the medial surface of the hyoglossus muscle

• drains into the internal jugular vein

– Submental vein : Anastomoses with the lingual v.’sbranches


Neurovascular supply of tongue


Lymphatic drainage

• The lymphatic drainage of the tongue and oral floor is mediated by

– Submental

– Submandibular groups of lymph nodes

• Ultimately drain into the lymph nodes along the internal jugular vein


Lymphatic drainage


References

• Grays Anatomy for Students 2nd Edition

• Head and Neck Anatomy for Dental Medicine

• Head, Neck and Dental Anatomy, 4th Edition

• Netter’s Head and Neck Anatomy for Dentistry, 2nd Edition Neil S norton

• Oral Development and Histology, 3rd Edition

• Woelfel's Dental Anatomy

• Ten Cate’s Oral Histology - Development, Structure, and Function, 7th Edition


tongue

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extrinsic muscles

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ventral surface of tongue