DEVELOPMENT OF DEVELOPMENT OF THE TONGUETHE TONGUE

by:by:

Dr. Carmina Romero GranadoDr. Carmina Romero Granado

tonguetongue

Largest single muscular Largest single muscular organ inside the oral organ inside the oral cavity.cavity.

Originates from the Originates from the muscles of occipital muscles of occipital myotomesmyotomes

Innervated by 5Innervated by 5thth, 7, 7thth, 9, 9thth & 10& 10thth cranial nerves cranial nerves

Extensive innervation is Extensive innervation is due to the long distance due to the long distance the muscle cells the muscle cells migrates to reach the migrates to reach the tongue & varied tongue & varied functions performedfunctions performed

Muscles travel in the Muscles travel in the paths of these various paths of these various nervesnerves

Parts of the tongueParts of the tongue

The first pharyngeal The first pharyngeal arch tissues forms the arch tissues forms the anterior (movable) body anterior (movable) body of the tongueof the tongue

The second & third The second & third arches form the arches form the posterior ( immovable) posterior ( immovable) body & base . body & base .

Tissues of the tongue Tissues of the tongue has 3 parts:has 3 parts:

The central The central tuberculum impar tuberculum impar & &

Two lateral lingual Two lateral lingual swellingsswellings

Formation of the TongueFormation of the Tongue

The tongue begins to The tongue begins to develop at about 4 develop at about 4 weeksweeks

Local proliferation of Local proliferation of the mesenchyme then the mesenchyme then gives rise to a number gives rise to a number of swellings in the floor of swellings in the floor of the mouthof the mouth

First, a swelling (First, a swelling (the the tuberculum impartuberculum impar) ) arises in the midline in arises in the midline in the mandibular process the mandibular process and is flanked by two and is flanked by two other bulges, the other bulges, the lingual lingual swellingsswellings

Very quickly these Very quickly these lateral lingual swellingslateral lingual swellings enlarge and merge with enlarge and merge with each other and the each other and the tuberculum impartuberculum impar to to form a large mass from form a large mass from which the mucous which the mucous membrane of the membrane of the anterior two thirds of anterior two thirds of the tongue is formedthe tongue is formed

The root of the tongue The root of the tongue arises from the arises from the hypobranchial hypobranchial eminenceeminence, a large , a large midline swelling midline swelling developed from the developed from the mesenchyme of the mesenchyme of the third archthird arch

Hypobranchial Hypobranchial eminence is the eminence is the primordial of the primordial of the epiglottis (thin plate epiglottis (thin plate of cartilage in front of cartilage in front of the glottis that of the glottis that protects it) during protects it) during swallowingswallowing

The mesenchyme of the The mesenchyme of the third arch rapidly third arch rapidly overgrows that of the overgrows that of the second arch, which is second arch, which is thereby excluded from thereby excluded from further involvement in further involvement in the development of the the development of the tonguetongue

The The hypobranchial hypobranchial eminenceeminence gives rise to gives rise to the mucous covering the the mucous covering the root, or posterior third root, or posterior third of the tongueof the tongue

Some authorities divide Some authorities divide the the hypobranchial hypobranchial eminenceeminence into an into an anterior copula (which anterior copula (which gives origin to the gives origin to the mucosa covering the mucosa covering the root of the tongue) and a root of the tongue) and a hypobranchial eminencehypobranchial eminence (which gives rise to the (which gives rise to the epiglottis)epiglottis)

The tongue separates The tongue separates from the floor of the from the floor of the mouth by a down mouth by a down growth of ectoderm growth of ectoderm around its periphery, around its periphery, which subsequently which subsequently degenerates to form the degenerates to form the lingual sulcus and gives lingual sulcus and gives the tongue mobilitythe tongue mobility

The The musclesmuscles of the of the tongue have a different tongue have a different origin: they arise from origin: they arise from the the occipital somitesoccipital somites, , which have migrated which have migrated forward into the tongue forward into the tongue area, carrying with them area, carrying with them their supply, the twelfth their supply, the twelfth cranial (hypoglossal) cranial (hypoglossal) nervenerve

This unusual development This unusual development of the tongue explains its of the tongue explains its innervationinnervation

Since the mucosa of the Since the mucosa of the anterior two thirds of the anterior two thirds of the tonguetongue is derived from the is derived from the first arch, it is supplied by first arch, it is supplied by the the fifth cranial nerve fifth cranial nerve (trigeminal nerve),(trigeminal nerve), whereas the whereas the mucosa of the mucosa of the posterior third of the posterior third of the tonguetongue, derived from the , derived from the third arch, is supplied by third arch, is supplied by the the ninth cranial nerve ninth cranial nerve (glossopharyngeal nerve)(glossopharyngeal nerve)

The body & base of the tongue differ in The body & base of the tongue differ in structure of the mucous membrane:structure of the mucous membrane:

anterior (body)- papillary in natureanterior (body)- papillary in nature Posterior (base)- lymphatic in naturePosterior (base)- lymphatic in nature

this are separated by a V-shaped sulcus known this are separated by a V-shaped sulcus known as as sulcus terminalis sulcus terminalis

The anterior 2/3 is divide into two lateral The anterior 2/3 is divide into two lateral halves by a halves by a lingual septum lingual septum w/c is w/c is manifested externally as manifested externally as median sulcusmedian sulcus

the dorsal mucosa covering the anterior part is the dorsal mucosa covering the anterior part is velvet like in appearance because of the velvet like in appearance because of the presence of invaginations & evaginations presence of invaginations & evaginations known as known as lingual papillalingual papilla

Types of lingual papilla:Types of lingual papilla:

4 types of lingual papilla:4 types of lingual papilla:

1.1. FiliformFiliform

2.2. FungiformFungiform

3.3. FoliateFoliate

4.4. circumvalatecircumvalate

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