Seminar By,Seminar By,Dr. Jacob AbrahamDr. Jacob Abraham

Dept. Of OrthodonticsDept. Of OrthodonticsS.R.M. Dental College,S.R.M. Dental College,

Chennai, IndiaChennai, India

NERVE INNERVATIONS NERVE INNERVATIONS &&

ITS APPLIED ANATOMYITS APPLIED ANATOMY

The face is the mirror of the mind, and eyes without The face is the mirror of the mind, and eyes without speaking confess the secrets of the heart. speaking confess the secrets of the heart.

St. JeromeSt. Jerome

MUSCLES OF FACIAL EXPRESSIONMUSCLES OF FACIAL EXPRESSION Generally from skull to skinGenerally from skull to skin Innervated by facial nerve Innervated by facial nerve

(CN VII)(CN VII) Sphincters and dilatorsSphincters and dilators

around mouth (lips), eyes, around mouth (lips), eyes, nostrilsnostrils

Wrinkle linesWrinkle lines perpendicular perpendicular to muscle fibresto muscle fibres

There are There are 1717 Muscles Muscles 1.1. Frontal Belly Of OccipitofrontalisFrontal Belly Of Occipitofrontalis2.2. Corrugator Super ciliaCorrugator Super cilia3.3. Orbicularis Occuli Orbicularis Occuli 4.4. Compressor NarisCompressor Naris5.5. Dilator Naris Dilator Naris 6.6. ProcerusProcerus7.7. Depressor SeptiDepressor Septi8.8. NasalisNasalis9.9. BuccinatorBuccinator10.10. Zygomaticus Major and MinorZygomaticus Major and Minor11.11. Levator labii Superioris alaeque nasiLevator labii Superioris alaeque nasi12.12. Depressor anguli orisDepressor anguli oris13.13. Levator Anguli SuperiorisLevator Anguli Superioris14.14. Depressor Labii InferiorisDepressor Labii Inferioris15.15. Orbicularis OrisOrbicularis Oris16.16. RisoriusRisorius17.17. MentalisMentalis

Frontal Belly of Ocipito Frontal Belly of Ocipito frontalisfrontalis:: Orgin :Orgin : Galea Galea

AponeuroticaAponeurotica Insertion:Insertion: Orbicularis Orbicularis

oculi and adjacent skin oculi and adjacent skin ActionAction: Draws scalp : Draws scalp

forward and raises forward and raises eyebrows eyebrows

MUSCLES OF FACIAL EXPRESSIONMUSCLES OF FACIAL EXPRESSION

MUSCLES AROUND THE EYEMUSCLES AROUND THE EYE

Sphincter: Sphincter: Orbicularis oculiOrbicularis oculi ((Orbital, palpebral and Orbital, palpebral and lacrimal partslacrimal parts))

BlinkBlink (spread tears across (spread tears across cornea) and close eyes tightly cornea) and close eyes tightly

Note:Note: elevators of upper lid elevators of upper lid innervated by innervated by CN IIICN III, , sympatheticssympathetics

MUSCLES OF EYEMUSCLES OF EYE

Orbicularis oculiOrbicularis oculi Sphincter muscle of eyelidSphincter muscle of eyelid OO: frontal & maxillary bones: frontal & maxillary bones II: tissue of eyelid: tissue of eyelid ActionAction: closes eye: closes eye NerveNerve: facial / CN VII: facial / CN VII

MUSCLES AROUND THE NOSEMUSCLES AROUND THE NOSE

Procerus - wrinkles skin of nose

Compressor nares – lateral to bridge of nose compresses nasal cartilage.

Dilator nares - lateral to nostrils – dilates

MUSCLES OF FACIAL EXPRESSIONMUSCLES OF FACIAL EXPRESSION

ZygomaticusZygomaticus Orgin:Orgin: zygomatic bone zygomatic bone Insertion:Insertion: corners of mouth corners of mouth Action:Action: smiling smiling Nerve:Nerve: facial / CN VII facial / CN VII

Major and Minor

MUSCLES AROUND THE MOUTHMUSCLES AROUND THE MOUTH

Numerous dilatorsNumerous dilators (levators/depressors of (levators/depressors of upper/lower lip and angle upper/lower lip and angle of mouth)of mouth)

BuccinatorBuccinator

Sphincter:Sphincter: Orbicularis oris Orbicularis orisSurrounds/closes mouth

MUSCLES OF MOUTH

Modiolus –Knitting of muscle fibers Modiolus –Knitting of muscle fibers

BuccinatorBuccinatorOrgin:Orgin: Maxilla and Maxilla and Mandible Mandible Insertion:Insertion: Angle of Angle of the mouth the mouth Action:Action: Retracts Retracts angle of mouth angle of mouth

MUSCLES OF FACIAL EXPRESSIONMUSCLES OF FACIAL EXPRESSION

Buccinator MuscleBuccinator Muscle Superior Pharyngeal Superior Pharyngeal

Constrictor Constrictor (SC)(SC) Pterygomandibular raphe Pterygomandibular raphe (PR)(PR) Middle Pharyngeal Constrictor Middle Pharyngeal Constrictor

(MC)(MC) Tonsillar Branch Of Facial Tonsillar Branch Of Facial

Artery Artery (1) (1)

Glossopharyngeal nerve Glossopharyngeal nerve (2)(2) Stylohyoid ligament Stylohyoid ligament (3)(3) The pterygomandibular raphe The pterygomandibular raphe

serves as an insertion point for serves as an insertion point for two muscles: two muscles:

Superior constrictorSuperior constrictor and and BuccinatorBuccinator

Common Facial ExpressionsCommon Facial Expressions Smiling & LaughingSmiling & Laughing: Zygomatics Major: Zygomatics Major SadnessSadness: Levator Labii Superioris and Levator : Levator Labii Superioris and Levator

Anguli Oris Anguli Oris GriefGrief: Depressor Anguli Oris: Depressor Anguli Oris AngerAnger: Dilator Naris & Depressor Septi : Dilator Naris & Depressor Septi FrowningFrowning: Corrugator Supercilii & Procerus : Corrugator Supercilii & Procerus Horror, Terror & Fight:Horror, Terror & Fight: Platysma Platysma SurpriseSurprise: Frontalis : Frontalis DoubtDoubt: Mentalis : Mentalis GrinningGrinning: Risorius: Risorius ContemptContempt: Zygomatic Minor: Zygomatic Minor

SMILING MUSCLES SMILING MUSCLES FROWNING MUSCLESFROWNING MUSCLES

Orbicularis Oculi:Orbicularis Oculi: close close eyelideyelid

Nasalis:Nasalis: compress/dilate compress/dilate nasal openingsnasal openings

Levator Labii SuperiorisLevator Labii Superioris: : raise upper lipraise upper lip

Levator Anguli SuperiorisLevator Anguli Superioris: : raise angle of mouth raise angle of mouth upwardupward

ZygomaticusZygomaticus: draw angle : draw angle of mouth upwardof mouth upward

Risorius:Risorius: draw angle of draw angle of mouth laterallymouth laterally

Frontalis:Frontalis: elevate elevate eyebrowseyebrows

Orbicularis Oris:Orbicularis Oris: closes closes mouthmouth

Depressor Anguli Oris:Depressor Anguli Oris: draw angle of mouth draw angle of mouth downwarddownward

Depressor Labii Inferioris:Depressor Labii Inferioris: lowers lower liplowers lower lip

Mentalis:Mentalis: draws chin up draws chin up Platysma:Platysma: draws lower lip draws lower lip

down & backdown & back

CUTANEOUS INNERVATION OF FACE CUTANEOUS INNERVATION OF FACE

Branches of trigeminal nerve Branches of trigeminal nerve (CN V):(CN V):

Ophthalmic (VOphthalmic (V11)) Maxillary (VMaxillary (V22)) Mandibular (VMandibular (V33))

Cervical plexus branches Cervical plexus branches (C2)(C2)

Lesser occipitalLesser occipital Great auricularGreat auricular

Greater occipital nerve Greater occipital nerve (dorsal ramus of C2) (dorsal ramus of C2)

MUSCLES & NERVE SUPPLYMUSCLES & NERVE SUPPLY

Orbicularis oculi Orbicularis oculi Temporal and Temporal and zygomatic brancheszygomatic branches

Muscles of Upper Lip andMuscles of Upper Lip and Buccal Branch Buccal Branch Buccinator, Levator Anguli Oris Buccinator, Levator Anguli Oris

Risorius and Risorius and Mandibular Branch muscles Mandibular Branch muscles of lower lipof lower lip

PlatysmaPlatysma Cervical Branch Cervical Branch

FACIAL NERVE FACIAL NERVE It has both It has both EfferentEfferent component and component and

AfferentAfferent component component Efferent component supplies all the Efferent component supplies all the

muscles and the glands such as themuscles and the glands such as the Lacrimal gland Lacrimal gland Submandibular glandSubmandibular gland Sublingual glandSublingual gland

Afferent component supplies the Afferent component supplies the Taste sensation of theTaste sensation of the Ant. Ant.22//33rdrd of the tongue of the tongue

Innervation Of Muscles Of Facial Expression: Innervation Of Muscles Of Facial Expression: Facial N. (VII)Facial N. (VII)

LMNs in facial nucleus is in inferior ponsLMNs in facial nucleus is in inferior pons Fibres course around abducens nucleus - internal genu Fibres course around abducens nucleus - internal genu Exits brainstem at cerebellopontine angle with CN VIIIExits brainstem at cerebellopontine angle with CN VIII

Course of facial nerve (CN VII)Course of facial nerve (CN VII) Through the petrous part of the temporal bone:Through the petrous part of the temporal bone:

Through internal acoustic meatus with CN VIIIThrough internal acoustic meatus with CN VIII Into facial canal, along walls of the tympanic cavity Into facial canal, along walls of the tympanic cavity

(external genu of facial nerve, geniculate ganglion)(external genu of facial nerve, geniculate ganglion) Exits skull via stylomastoid foramen, most Exits skull via stylomastoid foramen, most

branches go through parotid glandbranches go through parotid gland TemporalTemporal ZygomaticZygomatic BuccalBuccal Marginal mandibularMarginal mandibular Cervical Cervical Posterior auricularPosterior auricular

Damage to UMNs, LMNs, or facial nerveDamage to UMNs, LMNs, or facial nerve Clinical testing:Clinical testing: raise eyebrows, close eyes tightly, smile raise eyebrows, close eyes tightly, smile Unilateral UMN:Unilateral UMN: contralateral lower 1/2-2/3 of face paralysed contralateral lower 1/2-2/3 of face paralysed Unilateral LMN or CN VII:Unilateral LMN or CN VII: entire ipsilateral face paralysed entire ipsilateral face paralysed

((Bell’s palsyBell’s palsy)) Lack of blinkingLack of blinking Leaky mouthLeaky mouth Speech difficultiesSpeech difficulties (other CN VII functions)(other CN VII functions)

A lesion involving the nuclear or infranuclear A lesion involving the nuclear or infranuclear portion of the facial nerve will produce a portion of the facial nerve will produce a peripheral facial palsy.peripheral facial palsy.

If all motor components are involved, there is If all motor components are involved, there is complete paralysis of all facial muscles on the complete paralysis of all facial muscles on the involved side. The involved side. The brow is smoothbrow is smooth, the eye does , the eye does not closenot close, the nasolabial , the nasolabial fold is flatfold is flat, and that side , and that side of the mouth of the mouth droopsdroops. There is . There is no movementno movement at at all. The paradigm of this type of involvement is all. The paradigm of this type of involvement is Bell's palsyBell's palsy. .

Idiopathic:Idiopathic: Bell's palsy may strike at Bell's palsy may strike at any age,any age, often after a often after a mild viralmild viral illness. Recovery is over a illness. Recovery is over a period of weeks to months and is variable. The period of weeks to months and is variable. The cause of the idiopathic variety is unknown. cause of the idiopathic variety is unknown.

If any injury to the nerve which supplies that If any injury to the nerve which supplies that muscle, it will lead to paralyses of that muscle. muscle, it will lead to paralyses of that muscle. This causes the dropping of lower eyelid , This causes the dropping of lower eyelid , called as called as “Ectropion’’“Ectropion’’ and and

Spilling of tears , called as Spilling of tears , called as “Epiphora”.“Epiphora”.

Some times there will be radiating wrinkles at Some times there will be radiating wrinkles at the angle of the eye during strong closure. This the angle of the eye during strong closure. This called as called as “Crow’s Feet”“Crow’s Feet”

Applied Anatomy For Orbicularis OculiApplied Anatomy For Orbicularis Oculi

Risorisus Sardonicus: Risorisus Sardonicus: Smile in tetanus Smile in tetanus It is the smile like feature in agony due to It is the smile like feature in agony due to

pulling of the muscles of the angle pulling of the muscles of the angle

ReferencesReferences

Cunningham’s Manual of Practical Cunningham’s Manual of Practical AnatomyAnatomy

B.D. ChaurasiaB.D. Chaurasia Gray’s AnatomyGray’s Anatomy InternetInternet