Muscles of facial expression neeha

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MUSCLES OF FACIAL EXPRESSION

Dr. A. NeeharikaIst year PG

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Contents

• Introduction• Various muscles and their action• Their Innervation• Applied anatomy

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Introduction-Mimetic Muscles

• The facial muscles are a group of striated skeletal muscles innervated by

the facial nerve (cranial nerve VII) which control facial expression. These

muscles are also called mimetic muscles.

• Facial Expressions- movements of mimetic musculature of the face

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• The facial musculature is fairly unique. They include the only somatic

muscles in the body attached on one side to bone and the other to skin;

thus facial movements are specialized for expression.

• The face is also one of the few places in the body where some muscles

are not attached to any bone at all (e.g., orbicularis oculi, the muscle

surrounding the eyes; orbicularis oris, the muscle in the lips).

• They also act as sphincters and dilators of the orifices of the face• Facial muscles develop from second pharyngeal arch.

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Groups

• For logical understanding, they are grouped as:1. Orbicular Group2. Nasal Group3. Oral Group4. Other muscles or groups

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Orbicular Group

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Orbicularis Oculi:Closes and squints the eye. Wink, concern, perplexion.

Levator Palpebrae Superioris: Elevates the upper eyelid. Surprise, fear

Corrugator Supercilii: Draws the eyebrow inferomedially and shows anger, concern

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Nasal Group

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Nasalis:Maxilla to the cartilage of the nose and the opposite side nasalis muscle. Compresses the nares.

Procerus:Fascia and skin medial to the eyebrow to the fascia and skin over the nasal bone (disdain look)

Depressor Septi Nasi:From medial fiber of dilator naris muscle to mobile part of nasal septum. Depresses septum and narrows nostril

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Oral Group

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Levator labii superioris :Infraorbital head & zygomatic head to upper lip. Raises upper lip; helps form naso -labial furrow. Disgust, smugness

Levator labiisuperioris alaeque nasi : Frontal nasal process to one to ala & other to orbicularis oris.Raises upper lip and opens Nostril. anger, contempt

Levator anguli oris :Maxilla below infraorbital foramen & canine fossa to angle of mouth. Elevates the angle of the mouth. smile, sneer, “Dracula” expression

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Zygomaticus major:From zygomatic bone & arch to angle of mouth. Draws the corner of the mouth upward and laterally. Smile, laugh

Zygomaticus minor:From zygomatic bone & medial to zygomatic major to nasolabial groove. Draws the upper lip upward. Smile & Smugness.

Risorius:From superficial fascia over parotid to skin & mucosa on angle of lip. Retracts corner of mouth. Grin, smile, laugh

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Depressor anguli oris / triangularis:From oblique line of mandible to angle of mouth. Draws corner of mouth down and laterally.

Depressor labii inferioris :From base of mandible to skin n mucosa of lower lip. Draws lower lip downward and laterally. Sadness, uncertainty, dislike

Mentalis :From mandible below lower incisors to skin of chin. Raises and protrudes lowerlip as it wrinkles skin on chin. doubt, pout, disdain

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Orbicularis Oris:From buccinator muscle to angle of mouth (upper lip) and mandible (lower lip). Closes lips; protrudes lips.puckering, whistling

Buccinator :From alveolar process f max. and mand. In region of molars & pterygomandibular ligament. Presses the cheek against teeth;Compresses distended cheeks. pucker, exertion, sigh

Platysma :From skin and superficial fascia of pectoral and deltoid region to lower border of mandible. Draws up the skin of the superior chest and neck. Creature from Black Lagoon” expression

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Other Group

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Occipitofrontalis : Frontal Belly: From ant. Part of Galea aponeurotica to Skin on lower part of forehead.Wrinkles forehead;Raises eyebrows

Anterior auricular: Draws earupward and forward

Occipital belly:From lateral 2/3rd ofSuperior nuchal lineTo post. Part of galea Aponeurotica. Draws scalp backward

Superior auricular : Elevates ear

Posterior Auricular: Draws earupward and backward

Cannot consciously move.Temperoparietalis has to be checked.

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Nerve Supply

Facial N. (VII)

• LMNs in facial nucleus is in inferior pons• It emerges from the brainstem between the pons and the medulla, and

controls the muscles of facial expression• The facial nerve is developmentally derived from the hyoid arch (second

pharyngeal branchial arch). The motor division of the facial nerve is derived from the basal plate of the embryonic pons, while the sensory division originates from the cranial neural crest.

Course:• Fibres course around abducens nucleus - internal genu Exits

brainstem at cerebellopontine angle with CN VIII Through the petrous part of the temporal bone Through internal acoustic meatus with CN VIII Into facial canal, along walls of the tympanic cavity (external genu of facial nerve, geniculate ganglion)

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Exits skull via stylomastoid foramen, most branches go through parotid gland

• Temporal• Zygomatic• Buccal• Marginal mandibular• Cervical • Posterior auricular

• The oculomotor nerve [III], which innervates the levator palpebrae superioris; sympathetic fibers, which innervate the superior tarsal muscle.

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• http://emedicine.medscape.com/article/1289133-overview

• http://emedicine.medscape.com/article/835286-overview#a30

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Applied Anatomy

Bell’s Palsy

• Charles Bell in 1821 first described Bell’s Palsy.

• It is Common, acute, benign neurological disorder, characterized by

sudden, isolated peripheral facial nerve paralysis

• Bell’s Palsy- Lower Motor Neuron Disorder.

• Various and unknown etiology

• However infectious, genetic, metabolic, autoimmune, vascular condition,

and nerve entrapment, viral etiology

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Clinical Features:

• Can be complete/ partial- only lower part of face is involved• Lack of facial expressions on one side• Patient is also unable to whistle, smile or grimace• Increased lacrimation, hypersensitivity to sound (hyperacusis), loss of

taste / metallic taste(chordatympani) and pain near mastoid area (70% of patients)

• Sudden facial weakness, difficulty with articulation, inability to keep an eye closed.

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• Clinical Evaluation:– Exclude etiologies like trauma, otologic disease, and intracranial – History- onset, course, duration – Facial creases, nasolabial fold- dissapear– Forehead unfurrows and corner of mouth droops– Eyelids will not close, and lower lid sag

- Tear production decreases, but appears to tear excessively as loss of eye lid control

- Postive Hitselberger sign- decreased sensation along the external acoustic meatus.

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Diagnostic evaluation

• Determine whether it is central or peripheral– Peripheral facial palsy involves all the facial muscles ipsilateral to the

side of facial nerve involvement– Central involves facial muscles contralateral to the lesion in the brain

stem above pons and cerebral hemisphere. • Familial history• Sudden onset or gradual

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• Physical examination to rule of Ramsay-Hunt syndrome• Serological tests like ELISA and PCR to rule out• Virological Analysis of endoneurial fluid obtained during decompression

surgeryrevelaed HSV-1 in 11 of 14 Bells’ Palsy Patients.*

*Gliden DH. Bell’s Palsy. N Engl J Med 2004:23;1323-31

• Electric test like Trans Temporal stimulation electromyography – presence of voluntary motor unit indicates continuity of nerve.

• Nerve Excitability test• Trigeminal blink reflex is the only test to measure the intracranial

pathway of facial nerve• Conventional radiographs, CT, MRI

Indian J Stomatol 2013;4(1):36-3927

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INFRANUCLEAR LESIONS (LMNs) SUPRANUCLEAR LESIONS (UMNs)

LMN lesion of facial nerve (Bell’s Palsy), the whole of the face of the same side gets paralyzed.

The face becomes assymetrical and is drawn up to normal side.

The affected side is motionless.

Wrinkles disappear and eye cannot be closed.

Peripheral Palsy

UMN lesions of Facial nerve is usually a part of hemiplegia.

Only the lower part of opposite side of the face is paralyzed.

The upper part of frontalis and orbicularis oris escapes due to its bilateral representation in the cerebral cortex.

Central Palsy

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Orbicularis oculi

• If any injury to the nerve supllying orbicularis oculi, it will cause paralysis of that muscle. This causes of drooping of the lower eyelid, called as ‘Ectropion’.

• Spilling of tears is called “Epiphora”.

Tetanus

• Tetanus is a clinical diagnosis characterized by a triad of muscle rigidity, muscle spasms and autonomic instability.

• Clostridium tetani spores enter into the body through any abrasions on the skin.

• Release tetanospasmin (potent neurotoxin)

C/F:• Early symptoms of tetanus include neck stiffness, sore throat, dysphagia

and trismus.• Spasm extending to the facial muscles causes the typical facial expression,

‘risus sardonicus’.• Truncal spasm causes opisthotonus.

Continuing Education in Anaesthesia, Critical Care & Pain | Volume 6 Number 3 200630

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Parkinson’s Disease

• Parkinson’s disease (PD) is a chronic, progressive, neurodegenerative disorder .

• Characterized by resting tremors, cogwheel rigidity, bradykinesia.• PD results from idiopathic degeneration of dopaminergic cells in the

pars compacta of substantia nigra Depletion of neurotransmitter dopamine in the basal ganglia

• The four cardinal signs of PD are resting tremor, rigidity or stiffness, bradykinesia and postural instability.

Congenital

• Mobius Syndrome

• It is an extremely rare congenital neurological disorder which is characterized by facial paralysis and the inability to move the eyes from side to side. Most people with Möbius syndrome are born with complete facial paralysis and cannot close their eyes or form facial expressions. Limb and chest wall abnormalities sometimes occur with the syndrome.

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• Melkersons-Rosenthal Syndrome It is a rare neurological characterized by recurring facial paralysis, swelling of the face and lips (usually the upper lip), and the development of folds and furrows

• Ramsay Hunt Syndrome:Peripheral facial nerve palsyMay be unilateral or bilateralVesicular rash on ear Ear pain, tingling, tearing, loss of sensation and nystagmus.

• Ramsay Hunt Syndrome Type II: Reactivation of latent Herpes zoster virus within the dorsal root

ganglion of facial nerve is associated with vesicles affecting ear canal.

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References:

• Text Book of anatomy- Inderbir Singh• Text of anatomy- B.D. Chaurasia• Cunningham Manual of Anatomy• Facial Palsy: A Review- Indian J Stomatol 2013;4(1):36-39• Continuing Education in Anaesthesia, Critical Care & Pain | Volume 6

Number 3 2006• Continuing Education in Anaesthesia, Critical Care & Pain | Volume 6

Number 3 2006• *Gliden DH. Bell’s Palsy. N Engl J Med 2004:23;1323-31