Muscles of Facial Expression Condensed Grayscale Slides

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    Muscles of Facial

    Expression

    Muscles of Facial

    Expression

    Alex ForrestAssoci ate Profess or of For ensic Od ontol ogyForensic Science Research & Innovation Centre, Griffith UniversityConsultant Forensic Odontologist,Queensland Health Forensic and Scientific Services,

    39 Kessels Rd, Coopers Plains, Queensland, Australia 4108

    Oral Biology

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    Do not remove this notice

    Learning ObjectivesLearning Objectives

    You should be able to explain the embryological origin of

    the muscles of facial expression, and to explain theresulting common motor nerve and blood supply

    You should be able to explain how the muscles of facial

    expression are classified.

    Learning ObjectivesLearning Objectives

    You should be able to demonstrate knowledge of the

    principal functions of the major groups of muscles offacial expression in normal function.

    You should be able to relate your understanding of

    muscle functions to origins and insertions.

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    Facial StructureFacial Structure

    The basic form of the face is determined largely by the

    underlying bony structures. These are covered by the soft

    tissues which comprise muscles, subcutaneous fat and

    other components.

    In some areas of the face, there is very little subcutaneous

    soft tissue. These areas include the upper part of the nose,the margins around the orbits, the forehead, and the area

    over the zygomatic arches, and around the lower border of

    the mandible.

    The bone can be palpated through the skin in these

    areas, and as a result the skin tends to be relatively

    immobile in these regions.

    Try this out on your own face (or that of a friend)now

    Facial StructureFacial Structure

    Facial StructureFacial Structure

    Other regions in the face are separated from the

    underlying bone by larger amounts of subcutaneous

    tissue.

    As a consequence, these areas tend to be more mobile

    when acted on by muscles, and are largely responsible for

    the facial expressions.

    These soft tissues are moved by a group of muscles

    which is therefore called the subcutaneous muscles of

    facial expression.

    ClassificationClassification

    This muscle group shares a common nerve supply; all

    motor supply to them comes from the facial nerve (VII).

    You will recall that the facial nerve arises from the hyoid

    arch or second branchial arch, and that the muscles of

    facial expression, including the platysma, are derived from

    this arch as well.

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    ClassificationClassification

    You should note that not all the muscles supplied by VII are

    classified as muscles of facial expression.

    Specifically, the stylohyoid muscle and the posterior belly of

    the digastric muscle are not included in this group,although they are derived from the muscle element of the

    2nd arch.

    ClassificationClassification

    Other muscles also play a part in determining facial

    expression, including the hypoglossal nerve (XII) (sticking

    the tongue out) and the oculomotor nerve (III) (rolling the

    eyes) but they are not classified in this group either.

    ClassificationClassification

    Most muscles of facial expression have a bony origin and

    insert into the soft tissue of the face.

    Some have variations on this theme. The buccinator

    originates from the pterygomandibular raphe, for

    instance, and the orbicularis oris has no bony attachment

    at all.

    ClassificationClassification

    The muscles of facial expression can be classified into groups:

    Muscles of the lips and cheeks

    Muscles of the nose

    Muscles of the eyelid

    Muscles of the auricle of the ear

    Muscles of the scalp

    Platysma muscle

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    Muscles of the

    Lips and Cheeks

    Muscles of the

    Lips and Cheeks

    Lips and CheeksLips and Cheeks

    The muscles of the lips and cheeks are divided into two layers:

    Superficial muscles

    Deep mu scles

    Lips and CheeksLips and Cheeks

    Superficial Layer:

    Levator labii superioris alaquae nasi

    Levator labii superioris

    Levator anguli oris

    Zygomaticus major & minor

    Risorius

    Depressor labii inferioris

    Depressor anguli oris

    Mentalis

    Lips and CheeksLips and Cheeks

    Deep Layer:

    Buccinator

    Orbicularis oris

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    Lips and CheeksLips and Cheeks

    Levator labii superioris alaquae nasi

    Levator labii superioris

    Levator anguli oris

    Zygomaticus major & minor

    Risorius

    Depressor labii inferioris

    Depressor anguli oris

    Mentalis

    Superficial Layer:

    Grays Anatomy, Longman, London, 35 th Edition, 1973. p 496.Van De Graff, K. Human Anatomy, Iowa, Wm. C. Brown, 2nd Ed., 1988. p. 246

    Levator labii superioris alaquae nasi

    Levator labii superioris

    Levator anguli oris

    Zygomaticus major & minor

    Risorius

    Depressor labii inferioris

    Depressor anguli oris

    Mentalis

    Superficial Layer:

    Lips and CheeksLips and Cheeks

    Lips and CheeksLips and Cheeks

    The muscles of the

    superficial layer

    converge on lips and

    enter them in a radialdistribution.

    They originate on the

    maxilla and mandible,

    on the zygomatic

    bones, and from the

    masseteric fascia.

    Grays Anatomy, Longman, London, 35th Edition, 1973. p 304. Mandible, External Surface

    Grays

    Anatomy,

    Longman,

    London, 35th

    Edition, 1973.

    p. 281.

    Lips and CheeksLips and Cheeks

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    Zygomatic Bone, Lateral Aspect

    Grays

    Anatomy,

    Longman,

    London, 35th

    Edition, 1973.

    p. 309.

    Lips and CheeksLips and Cheeks

    Many of these

    superficial muscles

    converge to insert on a

    vertical

    musculotendinous

    raphe close to the

    corner of the mouth.

    This is known as themodiolus, and is visible

    through the skin as a

    surface feature on the

    face.

    Lockhart RD, Living Anatomy. London, Faber & Faber 7th Ed. 1974, p. 16

    Lips and CheeksLips and Cheeks

    Orbicularis OrisOrbicularis Oris

    The fibres oforbicularis oris

    form a kind of

    sphincter around

    and within the

    lips.

    Grays Anatomy, Longman, London, 35th Edition, 1973. p 496.

    Orbicularis OrisOrbicularis Oris

    A small number of fibres attach to the maxilla and mandible in

    the area associated with the sockets of the incisors (frenula).

    Some fibres insert into the modiolus, while others insert on the

    deep surfaces of the skin and mucous membrane of the mouth.

    University of Queensland School of Dentistry 2001

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    Orbicularis OrisOrbicularis Oris

    Contraction of its fibres

    draws the lips together,

    and tight contraction

    causes pursing of the lips

    as in pouting or whistling.

    The lips are parted by

    relaxation of the orbicularis

    oris with simultaneouscontraction of the maxillary

    and mandibular radiating

    muscles.

    Van De Graff, K. Human Anatomy, Iowa, Wm. C. Brown, 2nd Ed., 1988. p. 247

    BuccinatorBuccinator

    The buccinator

    muscle lies deep

    within the cheeks and

    is closely related to

    the buccal mucous

    membrane.

    Grays Anatomy, Longman, London, 35th Edition, 1973. p 496.

    BuccinatorBuccinator

    Posteriorly it attaches

    to the

    pterygomandibular

    raphe.

    Superiorly it attaches

    to the alveolar process

    of the maxilla, and

    below to that of the

    mandible.

    Modified from: Grays Anatomy, Longman, London,

    35th Edition, 1973. p 499.

    BuccinatorBuccinator

    Anteriorly its deeper fibres insert into the modiolus, andthe superficial ones insert into orbicularis oris.

    Many of its fibres decussate prior to insertion to

    strengthen the angle of the mouth.

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    NoseNose

    No detail need be known

    Orbit & EyelidOrbit & Eyelid

    Each eyelid is given a degree of rigidity by a dense fibrous

    structure, the tarsal plate.

    Grays Anatomy, Longman, London, 35th Edition, 1973. p 498.

    Orbit & EyelidOrbit & Eyelid

    The principal muscle of the eyelid region is the orbicularis

    oculi. This comprises an orbital part, which overlies the bone

    surrounding the orbital cavities, and a palpebral part which

    is situated within the eyelids.

    Grays Anatomy, Longman, London, 35th Edition, 1973. p 498.

    Orbit & EyelidOrbit & Eyelid

    Both parts are attached to the medial palpebral ligaments at

    the medial corners of the orbits, and to the adjacent bones.

    Clemente CD, Anatomy, A Regional Atlas of the Human

    Body, Munich, Urban & Shwarzenberg, 1975, Diagram 485.

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    Orbit & EyelidOrbit & Eyelid

    The orbital fibres radiate

    around the orbits. They

    insert into the overlying

    skin.

    The palpebral fibres insert

    into the skin of the eyelidsand into the tarsal plate

    and lateral palpebral

    ligament.

    Grays Anatomy, Longman, London, 35th Edition,

    1973. p 496.

    Orbit & EyelidOrbit & Eyelid

    The palpebral fibres of

    the orbicularis oculi close

    the eyelids gently, as in

    sleeping.

    The orbital fibres draw

    the eyebrows down as in

    frowning, and helpforcibly close the eyes,

    as in an expression of

    agony.

    Grays Anatomy, Longman, London, 35th Edition,

    1973. p 496.

    AuricleAuricle

    No detail need be known

    ScalpScalp

    The scalp consists of five layers. From superficial to deep,

    these are:

    S Skin

    C Connective Tissue

    A Aponeurosis

    L Loose Connective Tissue

    P Periosteum

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    ScalpScalp

    The epicranial

    aponeurosis is a

    tendinous sheet into which

    the frontalis muscle

    attaches anteriorly, and

    the occipitalis muscle

    attaches posteriorly.

    At the side of the skull, theaponeurosis unites with

    the underlying temporal

    fascia.

    Clemente CD, Anatomy, A Regional Atlas of the Human

    Body, Munich, Urban & Shwarzenberg, 1975, Diagram 453.

    ScalpScalp

    The aponeurosis is loosely

    attached to the underlying

    periosteum, so some

    movement is permitted.

    The American Indians

    used to take advantage ofthis loose connection in

    the process of scalping

    their victims.

    Clemente CD, Anatomy, A Regional Atlas of the Human

    Body, Munich, Urban & Shwarzenberg, 1975, Diagram 453.

    ScalpScalp

    The fibres of the frontalis

    attach to bone in the

    region of the root of the

    nose via fibres that areknown as the procerus

    muscle.

    Its intermediate fibres

    insert on the skin of the

    eyebrows and forehead.

    Clemente CD, Anatomy, A Regional Atlas of the Human

    Body, Munich, Urban & Shwarzenberg, 1975, Diagram 453.

    ScalpScalp

    The occipitalis attaches to the superior nuchal lines of the

    temporalis muscle.Together, the frontalis and occipitalis muscles can move

    the aponeurosis and the overlying skin, but the amount of

    movement varies between individuals.

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    In the LabIn the Lab

    As you study these structures, you will find that virtually all

    textbooks referring to the anatomy of the head and neck

    contain diagrams of these muscles to a greater or lesser

    extent.

    In the LabIn the Lab

    You should take the opportunity to examine skulls during

    your practical sessions in detail.

    Feel the bones with your fingers. Can you feel

    roughnesses in the bone surface in the places you expectthe muscles to attach?

    The End