Tongue and Its Musculature

“Tongue and its musculature”

By:-

Sanket chakraverty 1st Year M.D.S Dept Of Prosthodontics Sree Balaji Dental College

CONTENTS

• introduction• Functions• External features• Mucous membrane• Muscles• Arterial supply• Venous supply• Nerve supply• Lymphatic drainage• Prosthodontic considerations• Influence and action of floor of the mouth• Applied anatomy

introduction

• Tongue is always the most integral part of oral anatomy. Its nature as such in prosthodontics has been controversial with its anatomy and action on lower dentures.

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

Functions Of Tongue

• Taste, speech, 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

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.

Digram showing external features.

ORAL OR PAPILLARY PART

• 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

•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

VALLATE PAPILLAE:VALLATE PAPILLAE:

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

FUNGIFORM PAPILLAE:FUNGIFORM PAPILLAE:

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

PAPILLAE OF THE TONGUE

• FILLIFORM PAPILLAE:FILLIFORM PAPILLAE:

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

MUCOUS MEMBRANE

• 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

extrinsic muscles

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

MEDIAN section AND LATERAL VIEW

INTRINSIC MUSCLES

Superior 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.

Genioglossus muscle

Origin Upper genial tubercle

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

Action Retract the tip, Depress tongue, Protrude the tongue

ACTION OF THE MUSCLE (prosthodontic view)

• 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.

•

• JPD :- {volume 15, number 3, may june 1965}

Genioglossus muscle

→ →

Hyoglossusmuscle

• 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

Styloglossus muscle

OriginTip and anterior surface of the

styloid process

Insertion Side of the tongue

actionPull the tongue upward and

forward

Action of the styloglossus muscle (prosthodontic view)

• When the muscle contract

↓

Terminating part of Alveolingual sulcus is lifted alongwith the mucousa.

↓

Dislocating the denture

• Generally, it’s a LINGUAL DISLOCACTING MUSCLE.

JPD :- {volume 15, number 3, may june 1965}

palatoglossus

• Origin• Oral 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.

Action of palatoglossus(prosthodontic view)

• It is also a lingual dislocating muscle.

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

• JPD :- {volume 15, number 3, may june 1965}

Nerve supply

• MOTOR NERVES:• Intrinsic & extrinsic muscles except

palatoglossus- Hypoglossal nerve.• Palatoglossus –Cranial part of Accessory n.

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

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.

VENOUS DRAINAGE

• Deep lingual vein is the principal vein.

• Runs backwards &unite to form lingual vein.

• Ends in either common facial vein or internal jugular vein.

DEVELOPMENT

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

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).

AGE CHANGES 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.

AGE CHANGES OF THE TONGUE

• 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.

ACTIVE MUSCULAR FIXATION

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

• It can be used to stabilize the dentures.

→→ ↑↑

PASSIVE 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.

Inclination of polished surfaces

• The buccal flanges of the lower denture must slope inferiorly and laterally.it shld extedn below the fold of buccinator muscle very definitely in the molar region.

• 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

Position of the 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.

“Prosthodontic considerations”

• It is necessary to establish objective diagnostic criteria of tongue motor skills for an objective evaluation of the masticatory function in complete denture wearers. It has been reported that motion-modulation images of the ultrasound system are effective for an objective evaluation of tongue motor skills.

(JPD 1997,VOL 77, 147-152).

• 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.

TONGUE SIZE

• 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.

HOUSE’S CLASSIFICATION OF TONGUE SIZES.

• 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

POSITION OF THE TONGUE

• 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.

INFLUENCE AND ACTION OF FLOOR OF THE MOUTH

• Suprahyoid muscles are the digastric, stylohyoid, mylohyoid and the geniohyoid.

• The mylohyoid and geniohyoid may influence the borders of the mandibular denture.

• The right and left mylohyoid muscles together form the floor of the mouth.

INFLUENCE AND ACTION OF FLOOR OF THE MOUTH

The mylohyoid muscle

• Origin: • From the whole length of mylohyoid line.

• Insertion: • Posterior fibers to the body of the hyoid bone. Middle and anterior fibers to the median

raphae that unites the right and left muscles.• Nerve supply: mylohyoid nerve.• Actions : • Elevates the floor of the mouth during swallowing. Depress the mandible and elevate the hyoid

bone.

The mylohyoid muscle

• The muscle lies deep to the sublingual gland in the region of 2 premolar. The posterior part of the muscle in the molar region affects the lingual impression border in swallowing and moving tongue.

• If the denture flange is extended below and

under the mylohyoid line, it will impinge on mylohyoid muscle and the action of the muscle can unseat the denture.

the distal-lingual extension should extend over the retro –molar pad

and about 3 mm below the mylohyoid ridge.

The thick lingual flange can dislodge the denture.

The mylohyoid muscle

• If the flange stops above the ridge, vertical forces will still cause soreness, and the seal will be broken easily.

• The denture flange can extend below, but not under the mylohyoid line.

• In cases of extensive bone loss, mylohyoid can be surgically detached and reattached inferiorly.

RETROMYLOHYOID FOSSA

• 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.

Alveololingual sulcus

• 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.

Anterior region

• 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

The middle 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 posterior 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

• 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.

FUNCTIONAL TONGUE CLASSIFICATION

• 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.

• 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

TEETH SETTING

• 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.

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

• 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.

PROSTHETIC RECONSTRUCTION OF MANDIBULAR TONGUE

• 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.

• 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.

REFERENCES

• 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.

• Internet

REFERENCES

• JPD-1955,VOL 5,629-635.

• JPD-1960,VOL 10,42-46.

• JPD-1963,VOL 13,857-865.

• JPD-1978,VOL 39,652-655.

• JPD-1997,VOL 77,147-152.

• JPD-2004,VOL 92,509-518.

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