MUSCLES OF FACIAL EXPRESSION BY: DR. NUZHAT NOOR AYESHA Iyr MDS, KCDS
CONTENTS INTRODUCTION DEVELOPMENT OF FACIAL MUSCLES CLASSIFICATION OF FACIAL MUSCLES FACIAL MUSCLES IN DETAIL- Origin, Insertion, Vascular Supply, Innervation & Action. APPLIED ASPECTS REFERENCES
INTRODUCTION FACIAL MUSCLES: • No other animal have evolved as complex a set of facial muscles as have humans • Morphologically, they represent remants of the Panniculus Carnosus, a continuous subcutaneous muscle sheet seen in some animals.
Characteristics of the facial muscles The primary function is expression of the emotions. The facial muscles are capable of performing 7000 expressions according to Coleman. They are also responsible for the maintenance of the posture of the facial structures. The facial muscle also contributes to stabilization of the mandible during the infantile swallowing and chewing and swallowing in the occlusally compromised adults. It is also important for the visual and the spoken communications.
DEVELOPMENT OF FACIAL MUSCLES
EMBRYOLOGY • Each pharyngeal arch consists of mesenchymal tissue, covered on outside by surface ectoderm and on inside by epithelium of endodermal origin. • . The mesoderm of the arches give rise to musculature of face and neck. Each arch is characterised by its own musculature and carry their own nerve
• The muscles of facial expression, the auricular muscles, stylohyoid, stapedius, posterior belly of digastric-originate from 2nd pharyngeal arch(hyoid arch). • The facial nerve, the nerve of 2nd arch supplies all these muscles.
CLASSIFICATION OF ORO-FACIAL MUSCLES Muscles of head Craniofacial muscles Masticatory muscles
Craniofacial Muscles Epicranial muscles Circumorbital and palpebral Nasal Buccolabial
Epicranial muscle group Occipitofrontalis Consists of 2 occipital and 2 frontal parts connected by epicranial aponeurosis
Origin • Occipital part – lateral 2/3rd highest nuchal line of occipital bone and mastoid part of temporal bone. • Frontal part – no bony attachments of its own , fibers blend with adjacent muscles. Insertion – into the epicranial aponeurosis.
Vascular supply • Superficial temporal , Opthalmic ,Posterior auricular and occipital arteries Innervation • Occipital part – posterior auricular branch of facial nerve • Frontal part – temporal branch of facial nerve
Action Frontal part • Acting from above – raise the eyebrows and skin over the root of the nose. • Acting from below – draw the scalp forward , throwing the forehead into transverse wrinkles. Occipital part – draws the scalp backwards • Acting alternatively – move the entire scalp backwards and forwards.
TEMPOROPARIETALIS • Lies between the frontal parts of occipitofrontalis and anterior and superior auricular muscles. Vascular supply • Superficial temporal , Opthalmic ,Posterior auricular and occipital arteries Innervation • Posterior auricular branch of facial nerve and the temporal branch of facial nerve
CIRCUMORBITAL AND PALPEBRAL GROUP Orbicularis oculi • Has orbital ,palpebral and lacrimal parts.
Orbital part Origin – nasal component of frontal bone , frontal process of maxilla and medial palpebral ligament.
Palpebral part – medial palpebral ligament and bone above and below the ligament.
• Lacrimal part – upper part of lacrimal crest and adjacent lateral surface of lacrimal bone. Insertion – skin around the margins of the orbit and tarsal plate.
Vascular supply – branches of facial , superficial temporal , maxillary , opthalmic arteries. Innervation – temporal and zygomatic branches of facial nerve. Action – closes eyelids palpebral part- gently closes eyelids orbital part- tightly closes them.
Corrugator supercilli Origin- from bone at the medial end of superciliary arch. Insertion – skin above the middle of the supraorbital margin. Vascular supply – superficial temporal , opthalmic arteries.
Innervation – temporal branch of facial nerve. Action – with oculi muscle shield the eye, involved in frowning , vertical wrinkles on the forehead.
NASAL MUSCLE GROUP Procerus Origin – facial aponeurosis covering lower part of nasal bone and upper part of lateral nasal cartilage. Insertion – skin over lower part of forehead between the eyebrows.
Vascular supply – branches from facial artery. Innervation – temporal and lower zygomatic branches of facial nerve. Action – transverse wrinkles over the bridge of nose , help to reduce the glare of bright light.
Nasalis • Consists of transverse and alar parts. • Tranverse - from maxilla just lateral to the nasal notch • Alar part – from maxilla below and medial to the transverse part Insertion – nasal cartilages.
Vascular supply –infraorbital branch of facial artery. Innervation – buccal branch of facial nerve. Action transverse- compresses the nasal aperture. alar -widening the anterior nasal aperture. -Deep inspiration
Depressor septi Origin – maxilla above the central incisor Insertion – mobile part of the nasal septum Vascular supply – superior labial branch of facial artery
Innervation – buccal branch of facial nerve Action – pulls the nasal septum downwards , with nasalis widens the nasal aperture.
Buccolabial group of muscles • Elevators , retractors , evertors of upper lip • Depressors, retractors, evertors of lower lip • A compound sphincter – orbicularis oris , incisivus superior and inferior. • Buccinator
Levator labii superioris alaequae nasi Origin – upper part of the frontal process of maxilla Insertion – greater alar cartilage of nose and skin over it , some fibers into lateral part of upper lip and floor of dermis at the nasolabial furrow and ridge. Vascular supply – facial artery and infraorbital branch of maxillary artery.
Levator labii superioris alaequae nasi Innervation – zygomatic and buccal branches of facial nerve. Action – raises and everts the upper lip, increases the curvature of top of nasolabial furrow , dilates the nostrils.
Levator labii superioris Origin – maxilla and zygomatic bone above the infraorbital foramen. Insertion– muscular substances of upper lip Vascular supply- facial artery and infraorbital branch of maxillary artery.
Levator labii superioris Innervation . – zygomatic and buccal branches of facial nerve. Action – elevates and everts the upper lip, modifies the nasolabial furrow.
Zygomatic major Origin – zygomatic bone just in front of zygomaticotemporal suture Insertion – at the angle of the mouth Vascular supply – superior labial branch of facial artery
Zygomatic major Innervation – zygomatic and buccal branches of facial nerve Action – draws the angle of the mouth upwards and laterally as in laughing
Zygomatic minor Origin – lateral surface of zygomatic bone behind the zygomaticomaxillary suture Insertion – muscular substances of upper lip Vascular supply. – superior labial branch of facial artery
Zygomatic minor Innervation – zygomatic and buccal branches of facial nerve Action – elevates the upper lip, exposing the max teeth , deepening and elevating nasolabial furrow, curl the upper lip in smiling, contempt.
Levator anguli oris Innervation – zygomatic and buccal branches of facial nerve Action – raises the angle of the mouth In smiling, depth and contour of nasolabial furrow
Levator anguli oris Origin – canine fossa of maxilla Insertion – into and below the angle of mouth Vascular Supply – superior labial branch of facial and infraorbital branch of maxillary arteries
Mentalis Origin – incisive fossa of mandible Insertion – skin of the chin Vascular supply - inferior labial branch of facial and mental branch of maxillary arteries
Mentalis Innervation – mandibular branch of facial nerve Action – raises the lower lip , wrinkling the skin of the chin, helps in drinking Expression – doubt
Depressor labii inferioris Origin – oblique line of the mandible between the symphysis menti and mental foramen Insertion – into the skin and mucosa of lower lip Vascular supply – inferior labial branch of facial , mental branch of maxillary artery
Depressor labii inferioris Innervation – mandibular branch of facial nerve Action – draws the lower lip downwards and little laterally and assist in eversion of lower lip Expression – irony , sorrow , doubt.
Depressor angular oris Origin – mental tubercle of mandible and its continuation, the oblique line –dep. labii inf. Insertion – at the angle of the mouth Vascular supply – inferior labial branch of facial , mental branch of maxillary artery
Depressor angular oris Innervation – buccal and mandibular branches of facial nerve Action – draws the angle of mouth downwards and laterally in opening mouth ,expressing sadness
Buccinator (whistling muscle) Origin - upper fibers from outer surface of alveolar process of upper molar teeth ,
- lower fibers from corresponding area of mandible ,
- middle fibers from pterygomandibular raphe
Buccinator (whistling muscle) Insertion – upper fibers into upper lip , - lower fibers into lower lip , - upper of middle fibers cross the angle of mouth to run into lower lip and lower of these fibers; similarly run into upper lip • Vascular supply – facial and buccal branch of maxillary arteries
Innervation – buccal branch of facial nerve • Action – compresses the cheek against the teeth and gums during mastication, and assist the tongue in directing food b/w the teeth
Orbicularis oris • Comprising of extrinsic and intrinsic parts. Extrinsic part – consists of fibers of other muscles which converge on the lips Intrinsic part – with in the lip consists 3 types of fibers – radiating , circular , antero - posterior
Orbicularis oris Vascular supply – superior , inferior labial branches of facial artery and mental , infraorbital branches of maxillary and transverse facial branch of superficial temporal artery Innervation – buccal and mandibular branches of facial nerve Action – varying kind of movements of lips like pouting , pursing , twisting
PURSING OF THE LIPS
Incisivus labii superioris Origin – floor of incisive fossa of the maxilla Insertion - modiolus Incisivus labii inferioris Origin - floor of incisive fossa of the mandible Insertion - modiolus
Risorius (grinning muscle) Origin – fascia covering the parotid Insertion – skin, mucous membrane of angle of mouth and orbicularis oris Vascular supply – superior labial branch of facial artery
Risorius (grinning muscle) • Innervation – buccal branch of facial nerve Action – pulls the corner of the mouth laterally - grinning and laughing
Platysma • Origin: upper parts of pectoral and deltoid fasciae. Fibres run upwards and medially. • Insertion: anterior fibres, to the base of mandible; posterior fibres to the skin of the lower face and lip and may be continous with the risorius. • Innervation: cervical branch of facial nerve
Action: releases pressure of skin on the subjacent veins; depresses mandible; pulls the angle of the mouth downwards as in horror or surprise.
Myotonia • Failure of Muscle relaxation after the cessation of voluntary contraction classified 3 types • Congenital • Acquired • Dystrophic
Dystrophic myotonia • Weakness of muscles including of jaw , face, neck levators of eyelids. • Ist occurs in hand, limb, arms Ptosis of eyelids, atrophy of masseter and sternocleido mastoid, weakness of facial muscles. ‘Myopathic facies’ and ‘Swan neck’.
Myasthenia gravis • Auto immune disease • Auto antibodies to acetyl choline receptors are seen • Profound weakness of muscles • diplopia , ptosis,drooping of face – sorrowful appearance of pt
• Dental interest- muscles of mastication and facial expression involved Pt has difficulty in mastication and deglutition, slow slurred speech Drooping eyelids is an early and prominent Tr t- anticholinesterases are sign. injected i/m “Sorrowful appearance”
FACIAL LACERATIONS • Facial soft-tissue injuries are not uncommon.The position and anatomy of the face make it particularly vulnerable to trauma • a systematic approach to facial laceration repair ensures the best chance at an optimum outcome
• Cosmetic results are better when minimal tension is placed on the wound edges at the time of repair. Therefore, wounds with the long axis parallel to the natural skin tension lines have much better cosmetic outcomes. The degree of tension on the wound edges can be estimated by measuring the distance, the wound edges retract away from the center of the lesion.
• Marked retraction (>5 mm) indicates strong skin tension. With such wounds, placement of dermal sutures in a 2-layer closure should be considered.
Facial Hemiatrophy • Characterised by progressive atrophy and wasting of subcutaneous fat, skin, cartilage, bone, muscle of essentially half of the face.
•Most common early sign is a painless cleft, ‘coup de sabre’ near midline of face/forehead. •Bluish hue may appear in skin overlying atrophic fat.
Facial Hemihypertrophy • Patients affected by condition exhibit an enlargement which is confined to one side of the body, unilateral macroglossia and premature development, and eruption as well as increased size of dentition. • Cause is unknown, but has been variously ascribed to vascular or lymphatic abnormaliities; CNS disturbances; and chromosomal abnormalities.
HEMIFACIAL MICROSOMIA • Syn-Goldenhar Syndrome, Brachial arch syn, Facio- auriculovertebral syn, lateral facial dysplasia. • This condition in which tissues on One side of face are underdeveloped affecting primarily ear, mouth and jaw areas. • Sometimes both sides of face can be affected.
REFERENCES BD Chaurasia’s; Human Anatomy, 10th edition. M Govindraj; Human Anatomy for BDS students, 1st edition. Gray’s Anatomy; Anatomical basis of clinical practise, 39th edition Grants; Atlas of Anatomy, 10th edition. Text book of oral pathology-Shafer
THANK YOU A man's face is his autobiography -Oscar Wilde