BY :- DR.MOHIT DHAWAN

M.D.S 1ST YEAR

PG. DEPT. OF PROSTHODONTICSB.R.S DENTAL COLLEGE

SULTANPUR(PANCHKULA)

THE TONGUE

introductionFunctionsExternal featuresMucous membraneMusclesArterial supplyVenous supplyNerve supplyLymphatic drainage

CONTENTS

Prosthodontic considerationsInfluence and action of floor of the mouth

Applied anatomy

Tongue is always the most integral part of oral anatomy.

every prosthodontist should have a proper knowledge of its anatomy to implement it for delivering a retentive denture.

introduction

FUNCTIONS OF THE TONGUE

Taste, mastication and deglutition.

The tongue takes part in the functions of sucking, swallowing, receiving food into the mouth, mastication,vocalization and speech.

In speech, this is the most accurate and fastest mechanisms of the body.

It plays an intrinsic part in the formation of sounds of vowels and consonants.

Functions Of Tongue

Control guide to direct the flow of the food and liquids to the pharynx.

Its a contributing factor in aiding normal positioning of erupting teeth in the dental arches as a counter pressure to facial muscles on the labial and buccal side of the teeth.

Acts as an additional thermal guide

EPITHELIUM

Anterior 2/3:- I st brachial arch.Posterior 1/3:- III rd brachial arch .Posterior most :- 4th brachial arch.

MUSCLES from Occipital myotomes

CONNECTIVE TISSUES from the local mesenchyme

DEVELOPMENT

EXTERNAL FEATURES

Diagram showing external features.

Body has 2 surfaces:

The dorsum, convex, curved upper surface.

The ventral surface, inferior surface.

The dorsum of the tongue is divided into: 1. an oral part( anterior two third) 2. A pharyngeal part ( posterior one

third)

The parts are separated by a faint v shaped groove, the sulcus terminalis.

External features

It is placed on the floor of the mouth.

It is covered by mucous membrane which consists of a layer of connective tissues & lined by stratified squamous epithelium.

it’s margins are free &are in contact with the gums &teeth.

ORAL OR PAPILLARY PART

in front of the palatoglossal arch each margin show 4-5 vertical folds – foliate papillae.

SUPERIOR SURFACE of the oral part shows a median furrow which is rough and covered with papillae.

INFERIOR SURFACE

INFERIOR SURFACE

• It is covered with a smooth mucous membrane, which shows a median fold called frenulum lingulae.

• On either side –prominence by deep lingual veins

• Laterally –fold called plica fimbriata directed towards the tip of the tongue.

• The folds converge anteriorly & terminate on either side of the lingual frenum in a small elevation called the sublingual caruncula or papilla. (warton’s duct opens here).

PHARYNGEAL (LYMPHOID)PART

Lies beneath the palatoglossal arches and the sulcus terminalis.

The mucous membrane has no papillae, but has many lymphoid follicles –collectively constitute the lingual tonsil.

posterior part of the tongue

The posterior part of the tongue is connected to the epiglottis by three folds of mucous membrane.

These are the median, right and left glossoepiglotic folds.

On either side of the median fold there is a pouch called the Vallecula.

PAPILLAE OF THE

TONGUE

PAPILLAE OF THE TONGUE

• Large 1-2mm diameter.• 8-12 in no.• Situated in front of sulcus terminalis.• Cylindrical projection.• Walls raised above the surface.

FUNGIFORM PAPILLAE:

• Numerous • Near tip and margins• Smaller than vallate but larger than filliform.• Narrow peduncle and rounded head• Bright red colour.

VALLATE PAPILLAE:

FILLIFORM PAPILLAE:

Cover the presulcular area of the dorsum.Velvety appearance.Smallest and numerous.Pointed and covered with keratin.

The mucous membrane of the tongue contains the receptors for the special sensory modality of taste.

Other sensory nerve endings permit the tongue to detect particle size of food, pain, temperature, pressure & even defects on natural teeth or a denture.

MUCOUS MEMBRANE

Mucous membrane forms papillae,& is adherent to the muscles.

Numerous glands, both serous & mucous lie deep to the mucous membrane.

Numerous taste buds are distributed throughout the mucous membrane.

Taste buds are not present in the middle of the tongue.

MUSCLES OF THE

TONGUE

It contains 4 intrinsic and 4 extrinsic muscles.

Intrinsic – (I) superior longitudinal (II) inferior longitudinal (III) transverse (IV) vertical

MUSCLES OF THE TONGUE

Extrinsic muscles:(I) genioglossus (II) hyoglossus(III) styloglossus(IV) palatoglossus.

extrinsic muscles

MEDIAN section AND LATERAL VIEW

INTRINSIC MUSCLESSuperior longitudinal

Shortens & makes the dorsum concave. lies beneath mucous membrane.

Inferior longitudinal

Shortens &makes the dorsum convex. Close to inferior surface between genioglossus and hyoglossus.

Transverse Makes the tongue narrow & elongated. Extends from median septum to margins.

Vertical Makes the tongue broad & flattened. Found in the borders of anterior part of tongue.

Origin Upper genial tubercle

Insertion Upper fibers: tip middle: dorsum Lower: hyoid bone

Action Retract the tip, Depress tongue, Protrude the tongue

Genioglossus muscle

It is a “lingual fixing muscle of the lower denture”.

The movements of the tongue esp the contraction is in conjunction with the lingual vertical and the genioglossus muscle that helps in the drawing of the tongue anteriorly towards the floor of the muscle.

Hence, it increases the pressure which the tip of the tongue can exert on the floor of the oral cavity and the alveolar process.

ACTION OF THE MUSCLE (prosthodontic view)

Genioglossus muscle

→ →

OriginGreater cornu & lateral part of body of hyoid bone

InsertionSide of the tongue between styloglossus & inferior longitudinalmuscle of the tongue

ActionDepress the tongue,Retrudes the tongue

Hyoglossusmuscle

OriginTip and anterior surface of the styloid

process

Insertion Side of the tongue

actionPull the tongue upward and forward

Styloglossus muscle

When the muscle contract

↓

Terminating part of Alveolingual sulcus is lifted alongwith the mucousa.

↓

Dislocating the denture

Generally, it’s a LINGUAL DISLOCACTING MUSCLE.

Action of the styloglossus muscle (prosthodontic view)

OriginOral surface of palatine aponurosis.

InsertionSide of the tongue at the junction of oral and

pharyngeal part of palatoglossal arch.

Action Touches the palate. thus preventing the bolus from

coming out.

palatoglossus

It is also a lingual dislocating muscle.

It is having the same action as that of the styloglossus muscle.

Action of palatoglossus(prosthodontic view)

MOTOR NERVES:Intrinsic & extrinsic muscles except palatoglossus-

Hypoglossal nerve.Palatoglossus –Cranial part of Accessory n.

through Pharyngeal plexus.SENSORY NERVESAnterior 2/3 –Chorda Tympani (Facial Nerve).General sensation -Lingual nerve.

Nerve supply

Nerve supply

• Posterior 1/3 –general taste &sensation- Glossopharyngeal nerve.

• Posterior most- Vagus nerve.

Arterial supply

Lingual artery which is a branch of external carotid artery .

The root is supplied by tonsillar & ascending pharyngeal arteries.

Deep lingual vein is the principal vein.

Runs backwards &unite to form lingual vein.

Ends in either common facial vein or internal jugular vein.

VENOUS DRAINAGE

LYMPHATIC DRAINAGE

Tip –bilaterally to Submental nodes.

The remaining right & left halves of anterior 2/3s drain unilaterally to submandibular nodes.

Posterior 1/3 drains bilaterally into jugulo-omohyoid nodes. (lymph nodes of the tongue).

A common nodular varicose enlargement of superficial veins on the undersurface of the tongue is seen.

Becomes smooth &glossy or red &inflamed in appearance.

Lingual mucosa – soreness, burning or abnormal taste sensations. (in elderly &postmenopausal women)

AGE CHANGES OF THE TONGUE

The presence of a retracted tongue affects the complete denture construction; however, its effect on denture function remains questionable. (J.Oral Rehab:2005 jun397-402)

Focal collections of chronic inflammatory cells are common, because of the infiltration of microorganisms or toxins through the thin epithelium of this region.

As the age increases the motor skills of the tongue decreases.

For complete denture wearers, the tongue plays an important role in the retention and stability of dentures.

Here, BRODIE spoke about the “Antagonistic” muscle groups.

It can be used to stabilize the dentures.

ACTIVE MUSCULAR FIXATION

→→ ↑↑

The resting muscles can be made to fix a denture by 2 condtions:-

By the inclination of the polished surfaces of the dentures.

By the polished surfaces of the denture between the cheeks and the lower lip on the one side and the tongue on the other side.

PASSIVE MUSCULAR FIXATION

The buccal flanges of the lower denture must slope inferiorly and laterally.

The lingual flanges also must extend inferiorly and medially below the anterior and lateral parts of the tongue, and as far as posteriorly by the range of the action of tongue and internal pterygoid muscle.

Inclination of polished surfaces

Inclination of polished surfaces

The position of the polished surfaces should be such that it can be wedged between the supporting structures.

It should be in equilibrium with the forces acting on both side.

Position of the polished surfaces

“Prosthodontic considerations”

Tongue thrusting habit tend to displace mandibular denture and sometimes maxillary denture also.

Measurement of the tongue force and fatigue indicate that long span edentulous state effects the musculature of the tongue. The tongue becomes stronger and this increase in strength must be considered.

(JPD 1963,,VOL 13,857-865, by Philip Rinaladi)

IMPRESSIONS:

Small narrow tongue –easy to make impressions. Poor border seal.

Broad thick tongue –makes impression making tough but provides good lingual seal.

HOUSE’S CLASSIFICATION OF TONGUE SIZES.

Class I: normal in size ,development & function.

Class II: teeth have been absent long enough to permit a change in form & function of the tongue.

TONGUE SIZE

Class III: the tongue is retracted & depressed into the floor of the mouth ,with the tip curled upward, downward or assimilated into the body of tongue.

Class I is ideal for prostheses .

Class II & III – Unfavorable

HOUSE’S CLASSIFICATION OF TONGUE SIZES.

WRIGHT ‘S CLASSIFICATION OF TONGUE POSITION.

Class I: Tongue lies in the floor of the mouth with the tip forward & slightly below the incisal edges of the mandibular anterior teeth.

Class II : The tongue is flattened & broadened but the tip is in a normal position.

POSITION OF THE TONGUE

Class III: the tongue is retracted & depressed into the floor of the mouth ,with the tip curled upward, downward or assimilated into the body of tongue.

Class I is ideal for prostheses .Class II & III – Unfavorable.

This is an area posterior to mylohyoid muscles.

Bounded by retromylohyoid curtain.

Posterolateral- overlies the superior constrictor muscle.

Posteromedial- covers the palatoglossal muscle.

Inferior- overlies submandibular gland.

RETROMYLOHYOID FOSSA

The denture border should extend posteriorly to contact retromylohyoid curtain when the tip of the tongue is placed against the front part of upper residual ridge.

RETROMYLOHYOID FOSSA

Protrusion of the tongue causes the retromylohyoid curtain to move forward.

The space between the residual ridge and the tongue which extends from lingual frenum to the retromylohyoid curtain.

Can be considered in 3 regions.

1. Anterior region : This extends from lingual frenum to where the mylohyoid curves down below the level of the sulcus. This depression is called premylohyoid fossa.

Alveololingual sulcus

This results from the concavity of the mandible joining the convexity of the mylohyiod ridge.

The lingual border of the impression in this anterior region should extend down to make definite contact with the mucous membrane floor of the mouth when the tip of the tongue touches the upper incisors

Anterior region

Extends from the premylohyoid fossa to the distal end of mylohyoid ridge curving medially from body of the mandible. The curvature is caused by prominence of mylohyoid ridge.

When the mylohyoid muscle and the tongue are relaxed, the muscle drapes back under the mylohyoid ridge. If the impression is made under these conditions,the muscle will be trapped under the ridge when the tongue is placed against upper incisors

The middle region

A slope of the lingual flange towards the tongue in the molar region allows the mylohyoid muscle to contract and raise the floor of the mouth without displacing the denture.

The middle region

This part is the retromylohyoid space or fossa.

It extends from the end of the mylohyoid ridge to the retromylohyoid curtain ( glossopalatine and superior constrictor muscles).

The denture border should extend posteriorly to contact the retromylohyoid curtain( the posterior limit of alveololingual sulcus) when the tip of the tongue is placed against the front part of upper residual ridge.

The posterior region

The distal end of the lingual flange turns buccally to fill the retromylohyoid fossa.

When the lingual flange is developed in this manner the border has a typical ‘s’ shaped curve

The posterior region

If the floor is too low ,so the dentist tends to over extend the denture flange, which leads to loss of retention because the denture flange impinges on the tissue & gets dislodged during the activation of the floor of the mouth.

The mandibular denture should be stable enough to resist a gentle push on the mandibular incisors by the tongue.

Tongue position has an important bearing on impression making and subsequent ability of the patient to manage with the mandibular denture.

All procedures leading to completing a lower impression should be done with tongue in its normal position.

According to the degree of activity and functional type:

1.occupational tongue.

2. Still tongue.

3.normal tongue.

4.habitual tongue.

JPD 1955,vol.5,629-635,by Barnett kessler.

FUNCTIONAL TONGUE CLASSIFICATION

Apply to those whose activities require increased tongue action: jurist, teachers. Lecturers.

This implies that the organ has developed a greater range of power movements which may results in trauma where flexibility in range is interfered with or restricted by prosthetic appliance.

2. Still:Limited activity due to injury or deformity.

Can not project the tongue forward much.

Passive tongue: tongue- tie.

3. Normal :Welcomed by prosthodontists as they give a range within limit2. s in effecting desirable rehabilitation.

4. Habitual: describes those disturbing power movements developed by habit.

The base of the tongue is thick and powerful and dislodging force is most offending to prosthetic denture.

It is suggested that the lower 2 molar in the prosthesis may be reduced buccolingually and may be set buccal to the ridge crest for stability

The actions of the tongue & cheek along with the esthetics ,primarily determine the lateral limits of the mandibular posterior teeth.

The teeth shouldn’t be placed more lingual than the extent of the ridge, since elevation of the tongue may dislodge the prosthesis.

TEETH SETTING

At rest after swallowing the tip gently touches the lingual surface of the lower anterior teeth.

The anterior teeth must not be set too far labially as the tongue normally rests on the anterior teeth.

The tongue assumes a position in which it’s lateral border is at the level of lingual contour of the lower natural posterior teeth.

TEETH SETTING

The dorsal surface is nearly at the level of the occlusal plane of posterior teeth.

It can be used as a good guide for the height of occlusal plane of artificial posteriors.

In prolonged edentulous patients the tongue is hypertrophied.

“Applied anatomy”

Injury to the hypoglossal nerve produces paralysis of the muscles of the tongue on the side of the lesion.

The lesion may be either infranuclear or supranuclear.

Infranuclear:- gradual atrophy of the affected half of the tongue.

Muscular twitching are also observed.

Seen typically in motor neuron disease & in syringobulbia.

Supranuclear lesions:- produce paralysis without wasting.

Seen in pseudobulbar palsy where the tongue is stiff & small

Glossitis is usually a part of generalized ulceration of the mouth cavity.

The presence of a rich network of lymphatic & of loose areolar tissue,in the substance of the tongue is responsible for enormous swelling of the tongue in acute glossitis.

The tongue fills up the mouth cavity & protrudes out.

The under surface of the tongue is a good site (along with the bulbar conjunctiva) for observation of jaundice.

In unconscious patients the tongue may fall back & obstruct air passages.

This can be prevented by lying the patient on one side with head down (the ‘ tonsil position’) or by mechanically pulling the tongue out.

In patients with grand mal epilepsy the tongue is commonly bitten between the teeth during the attack.

This can be prevented by hurriedly putting a mouth gag at the onset of the seizure.

Carcinoma of the tongue is quite common.

It is treated by radiotheraphy than by surgery.

Carcinoma of the posterior 1/3rd of tongue is more dangerous due to bilateral lymphatic spread.

Lingual cusps of upper premolars protrude lingually and restrict lateral border of anterior 3rd of the tongue- needs reduction and trimming of premolars.

Positioning of lower posteriors lingually off the ridge causes restriction of tongue movement- lack of space for the tongue to stretch and relax- tongue extend towards the throat- difficulty in breathing.

APPLIED ANATOMY JPD 1960,vol 10,42-46,by Joseph.s.Landa

Insufficient vertical dimension causes excessive friction of the dorsum against the palatal vault and occlusal surfaces of upper teeth- Affects phonetics an deglutition.

When dentures are worn for many years with insufficient vertical dimension, papillae in the anterior 3rd and middle 3rd are obliterated leading to smooth and shiny tongue.

APPLIED ANATOMY JPD 1960,vol 10,42-46,by Joseph.s.Landa

A total glossectomy or laryngectomy results in loss of basic vital functions and loss of speech.

In these patients fabrication of a mandibular tongue prosthesis can be done.

Procedure: Diagnostic casts are made and articulated. Mandibular RPD is constructed with a chrome cobalt

alloy mesh work which extends to the floor of the mouth.

PROSTHETIC RECONSTRUCTION OF MANDIBULAR TONGUE

Superior portion of the tongue is concave in form to permit food and liquid to pass posteriorly towards the pharynx.

This tongue prosthesis is effective in improving esthetics and function of the patient.

Tongue prosthesis is constructed from soft medical grade silicon rubber with a flexible tip.

Mesh openings in the alloy meshwork mechanically lock the silicone tongue prosthesis in position.

When teeth comes in contact the tip of the tongue touches the rugae area of the maxilla.

↓

↓

Superior portion of the tongue is concave in form to permit food and liquid to pass posteriorly towards the pharynx.

This tongue prosthesis is effective in improving esthetics and function of the patient.

B.D.Chaurasia’s-Human anatomy

Boucher’s-Prosthodontic treatment for edentulous patients.

Clinically oriented anatomy- Moore and Dalley.

Winkler’s-Essentials of complete denture prosthodontics.

Wikipedia Gray,s anatomy

REFERENCES

JPD-1955,VOL 5,629-635.

JPD-1963,VOL 13,857-865.

JPD-1978,VOL 39,652-655.

(J.Oral Rehab:2005 jun397-402)Hps online .com

REFERENCES

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