The vestibulo-ocular reflex (VOR) is a reflexeye movement that stabilizes images on the retina during head movement by producing an eye movement in the direction opposite to head movement, thus preserving the image on the center of the visual field. For example, when the head moves to the right, the eyes move to the left, and vice versa. Since slight head movement is present all the time, the VOR is very important for stabilizing vision: patients whose VOR is impaired find it difficult to read using print, because they cannot stabilize the eyes during small head tremors. The VOR does not depend on visual input and works even in total darkness or when the eyes are closed. However, in the presence of light, the fixation reflex is also added to the movement.
Muscles of facial expression
PRESENTED BY –DR. SHEETAL KAPSE1st YEAR, P.G. STUDENT
INTRODUCTION FACE Forehead iscommon to both face & scalp.
FACIAL MUSCLES Orbital margins & eyelids External nose & nostrils Lips, cheeks & mouth Pinna Scalp Cervical skin Muscles of facial expressions
Specificity of facial muscles These muscles are different from other muscle organization in having lack of deep membranous fascia beneath the skin of face. Many small slips of muscles, which are attached to the facial skeleton are inserted directly into skin (subcutaneously).
Importance of arrangement Primary & secondary functionSPHINCTOR & DILATOR OF FACIAL ORIFICES V/S Facial expression
Actions –1. Sphincter of orbital fissure2. Ocular reflex3. Accommodate the amount of light entering into eye4. Controls drainage of tears
Corrugatorsupercilii Pyramidal muscle Located at the medial end of eyebrow Deep to frontalis Blood supply – superficial temporal opthalmic arteryAction –1. Draws the eyebrow medially2. Frowning Nerve supply – temporal branch3. Vertical strip on supranasal strip of forehead
Levator palpebrae superioris Triangular muscle Arises from lesser wing of sphenoid, infront of optic foramen But separated by superior rectus
Blood supply –Directly by opthalmic arteryIndirectly by supraorbital branchNerve supply –CN IIISympathetic pluxes around CN IIIActions –1. Elevates upper eyelid2. Linked to superior rectus by check ligament3. Increased sympathetic activity – widened palpebral apparatus4. Lesion of sympathetic pluxes - ptosis
Procerus Pyramidal muscle Close to Origin – periosteum over lower part of nasal bone perichondrium over lateral nasal cartilage aponeurosis of transverse nasalis Insertion – glabellar skin over lower part of forehead between the eyebrows
Action –1. Draws the eyebrow medially & forms transverse wrinkles on lower part of forehead2. Frowning & concentration3. Reduces the glare of sunlight Blood supply – branches of facial artery Nerve supply – temporal branch zygomatic branch
procerus Nasalis Transverse2 parts – part1. Transverse component / compressor naris2. Alar part / pars alaris/ dilator naris posterior Alar part Depressor septiAttached to skin & posterioir part of mobile septum Blood supply – branches of facial artery infraorbital branch of maxillary artery Nerve supply – buccal branch zygomatic branchActions –Compression of narisWidening of naris & elongation of noseActive immediately before inspiration
•Primary dilator of nostril •Prevents the closure of nasal wall duringDilator Naris Anterior inspiration
Depressor Septi Absent or rudimentary. Depressor septiBlood supply – superior labial branch of facial arteryNerve supply – buccal & zygomatic branches Actions – 1. Pulls the nasal columella, septum & tip of nose downward 2. With alar part of nasalis – widens the nasal apperture causing nose to dip on smiling.
Blood supply – superior labial branch of facial arteryNerve supply – buccal & zygomatic branches
Actions –Lateral slip -1. Raises & evert the upper lip.2. Raises, deepens & increases the curvature of top of nasolabial fold.Medial slip -1. Pulls the lateral crus superiorly2. Along with depressor septi – secondary dilator of nose
Blood supply – superior labial branch of facial arteryNerve supply – buccal& zygomatic branches Actions – 1. Elevates & everts the upper lip 2. Modifies the nasolabial furrow 3. Along with LLSAN & LLS – curls the upper lip in smiling 4. Expressions - smugness (too obviously pleased with oneself) - contempt ( very low opinion) - disdain ( to be too proud)
Blood supply – superior labial branch of facial artery infraorbital branch of maxillary arteryNerve supply – buccal& zygomatic branches Actions – 1. Raises the angle of mouth on smiling 2. Contributes to depth & contour of nasolabial furrow
MentalisConical fesciculusLying at the side of mandibular labial frenulum
Blood supply – inferior labial branch of facial artery mental branch of maxillary arteryNerve supply – marginal mandibular Actions – 1. Raising, protruding & everting the lower lip 2. Wrinkling of skin of lower lip
Blood supply – inferior labial branch of facial artery mental branch of maxillary arteryNerve supply – lower buccal & marginal mandibular Actions – 1. Draws the angle of mouth downward 2. Expressions – sorrow
Buccinator Muscle of cheek Quadrilateral Between maxilla & mandible 3 parts-1. Upper fibers2. Middle fibbers3. Lower fibersPosterior partAnterior part
Blood supply – branches from facial artery branches from maxillary arteryNerve supply – branches from facial nerve Actions – 1. Compresses the cheek against the gums 2. When cheek are distended with air the buccinator expel it between lips – important for playing wind instruments. Buccinator – Latin : trumpeter trumpet – a brass musical wind instrument with a high clear tone.
Relations of buccinator PosteriorlyCovered withbuccopharyngeal fascia
Blood supply – superior labial branch of facial artery mental branch of maxillary arteryNerve supply – buccal branch of facial nerveActions –Pulls the corner of mouth laterally in grinning & laughing.
Platysma Origin – from pactoral & deltoid fascia Insertion – lower border of body of mandible & skin over the lower neck Muscle of neck & contributes to orbicularis oris complex 3 parts1. Mandibular2. Labial3. Modiolar
Blood supply –1. facial artery2. occipital artery3. posterior auricular artery4. subclavian arteryThey form a rich network within platysma & account for the viability of various skin flaps raised during neck dissection.
Blood supply – superior labial branch of facial artery mental branch of maxillary arteryNerve supply – buccal branch of facial nerve greater auricular nerve transverse cutaneous nerve of neckActions –1. Release pressure of skin on the subjacent vein2. Depresses the mandible forcefully3. Pull the angle of mouth downward4. Depresses & wrinkles the skin of lower face & mouth5. Tenses the skin of neck
Functional Grouping Of Facial Muscles Opening Sphincter DilatorPalpebral fissure Orbicularis oculi 1. Levator palpebrae superioris 2. Frontalis part of occipitofrontalisNostrils Compressor naris 1. Dilator naris 2. Levatoe labii superioris alequae nasi 3. Depressor septiOral fissure Orbicularis oris All muscles arround the mouth except Orbicularis oris & mentalis
Cleft lip cases - Nasal septum deviated to non-cleft side due to absence of correct insertion of transverse muscle of nose & orbicularis oris on medial aspect of cleft onto the tissue around the anterior nasal spine , nasal septum & most important contralateral muscle. 3 functional groups of facial muscles displaced inferiorly
Mangement of facial palsy -1. Reanastomosis of facial nerve stem – some voluntary & emotional expressions.2. Adams transplanted – anterior fibers of masseter – on both lips Requires 2-3 months temporalis muscle fiber – eyelids for function properly part of frontalis – to other side3. Adour et al transplanted masseter – facial muscles – successful best result by – stripping fascia from masseter & suture the paralyzed muscles on its raw surface.
Examination of facial muscle Frontalis Dilators of mouth Orbicularis oculi Buccinator
Wrinkle lines The direction in which facial skin tension is greatest varies regionally. Skin tension lines which follow the furrows formed when the skin is relaxed are known as ‘relaxed skin tension lines’ (Borges & Alexander 1962). In the living face, these lines frequently (but not always) coincide with wrinkle lines and can therefore act as a guide in planning elective incisions.A, Distribution of relaxed skin tension lines (Kraissls lines) lateral view. B, Anterior view.
When lesions on the face such as scars, pigmented lesions and skin cancers are excised, the dimensions of these lesions often require excision as an ellipse, so that the resulting defect can be closed as a straight line. If the resulting scar is to be aesthetically acceptable it is important to make the long axis of the ellipse parallel to the natural relaxed skin tension lines, so that the scar will look like a natural skin crease.
RESOURCESTEXT BOOK –1. B.D. Chaurassia’s human anatomy 4th edition vol. 3 The Head & Neck.2. Gray’s Anatomy 40th edition.3. Botulinum Neurotoxin For Head & Neck Disorder – by Blitzer , Benson & Guss.4. Surgical Approaches To Facial Skeleton 2nd Edition – by Edward Ellis & Michael F. Zide