the musculature of the head

THE MUSCULATURE OF THE HEAD

The Two Groups of the Muscles of the Head

1. Craniofacial muscles- related mainly to the orbital margins and eyelids, the external nose and nostrils, the lips, the cheeks and mouth, the pinna, scalp, and cervical skin. These are collectively referred to as the muscles of facial expression.

Common Characteristics of the Muscles of Facial Expression

All are inserted into the skin of the face;

All are supplied by the muscular branches of the facial nerve

2. Masticatory muscles-- concerned primarily with the

movements of the temporomandibular joint.

The Musculature of the Head

The craniofacial muscles

The CraniofacialMuscles The craniofacial

muscles receive their innervation from the branches of the facial nerve.

They are grouped as:1. epicranial2. circumorbital and palpebral3. nasal4. buccolabial

1. The Epicranial Muscles

The epicranius is made up of two main parts:

1. Occipitofrontalis

2. Temporoparietalis

The Epicranius

1. Occipitofrontalis- covers the dome of the skull from

the highest nuchal lines to the eyebrows. It is a broad, musculofibrous layer consisting of four thin, quadrilateral parts- two occipital and two frontal- connected by the galea aponuerotica.

The Epicranius

2. Temporoparietalis- variably developed sheet of muscle that lies between the frontal parts of the occipitofrontalis and the anterior and superior auricular muscles.

Superficial fascia of the scalp

- is firm, dense and fibro adipose, and adheres closely to bothe skin and the underlying epicranius, including its epicranial aponeurosis, the galea aponuerotica. Posteriorly it is continuous with the superficial fascia of the back of the neck. Laterally it is prolonged into the temporal region, where it is looser in texture.

The Muscles of the Scalp

MuscleMuscle ActionAction

FrontalisFrontalis Pulls the scalp up and backPulls the scalp up and back

OccipitalisOccipitalis Pulls the scalp backward and Pulls the scalp backward and forward forward

2. Circumorbital and Palpebral Muscles

This group of muscle if composed of the

following:1. orbicularis oculi,

2. corrugator supercilii, 3. and levator palpebrae superioris.

Orbicularis Oculi

- is a broad, flat elliptical muscle which surrounds the circumference of the orbit and spreads into the eyelids, anterior temporal region, infraorbital cheek, and superciliary region. It has three main parts:

1. Orbital2. Palpebral3. Lacrimal


Orbital partOrbital part Closes eyes forcefullyCloses eyes forcefully

Palpebral partPalpebral part Closes the eye gentlyCloses the eye gently

Lacrimal partLacrimal part Squeezes lubricating tears Squeezes lubricating tears against the eyeballagainst the eyeball

Corrugator Supercilii

- a small pyramidal muscle located at the medial end of each eyebrow, deep to the frontal part of the occipitofrontalis and orbicularis oculi, with which it is partially blended.

MuscleMuscle ActionActionCorrugator superciliiCorrugator supercilii Vertical wrinkling of the Vertical wrinkling of the

bridge of the nose as in bridge of the nose as in frowningfrowning

3. Nasal Muscles

The nasal muscle group is composed of the following muscles:

1. Procerus2. Nasalis3. Depressor

septi

Procerus

- is a small pyramidal slip close to, and often partially blended with, the medial side of the frontal part of the occipitofrontalis muscle.

Nasalis

- consists of transverse and alar parts which may be continuous at their origins. The transverse part is also known as the compressor nares and the alar part is the dilator nares.

Depressor Septi

- is often regarded to as part of the dilator naris.


Depressor septiDepressor septi Draw the septum downwards Draw the septum downwards to narrow the nostrilsto narrow the nostrils


ProcerusProcerus Transverse wrinkling of the Transverse wrinkling of the bridge of the nosebridge of the nose

NasalisNasalis

CompressorCompressor

NaresNaresCompresses the nostrilsCompresses the nostrils

Dilator NaresDilator Nares Dilates or flares the nostrilsDilates or flares the nostrils

4. Buccolabial Muscles

The shape of the buccal orifice and the posture of the lips are controlled by a complex three-dimensional assembly of muscular slips. These include:

I. Elevators, retractors, and evertors of the upper lip

II. Depressors, retractors, and evertors of the lower lip

III. A compound sphincter

I. elevators, retractors, and evertors of the upper lip :

levator labii superioris alaque nasi,

levator labii superioris,

zygomaticus major and minor,

levator anguli oris,

and risorius

Depressors, retractors, and evertors of the lower lip

depressor labii inferioris,

depressor anguli oris, and

mentalis

A compound sphincter:

orbicularis oris,

accessory muscles to the

orbicularis oris

incisivus superior, and

incisivus inferior


Levator labii superioris alaque Levator labii superioris alaque nasinasi

Elevate the ala of the nose and Elevate the ala of the nose and the upper lipthe upper lip

Zygomaticus majorZygomaticus major Draws the angle of the mouth up Draws the angle of the mouth up and back as in smiling or laughingand back as in smiling or laughing

Zygomaticus minorZygomaticus minor Deepen the nasolbial groove as in Deepen the nasolbial groove as in sorrowsorrow


Levator labii superiorisLevator labii superioris

Elevates the upper lip and Elevates the upper lip and flares the nostrilsflares the nostrils

Gives the expression of Gives the expression of sadnesssadness

Contraction of the whole Contraction of the whole muscle gives the expression muscle gives the expression of disdain or doubtof disdain or doubt


Levator anguli oris or caninusLevator anguli oris or caninus Elevates the angle of the Elevates the angle of the mouth (muscle of happiness)mouth (muscle of happiness)

MentalisMentalis Elevate the chin. It also Elevate the chin. It also causes trembling of the chin. causes trembling of the chin. It wrinkles the skin of the chin It wrinkles the skin of the chin as in disdain or doubt.as in disdain or doubt.


RisoriusRisorius Draw the anglef the mouth Draw the anglef the mouth laterally, giving an expression laterally, giving an expression of strain or tensenessof strain or tenseness

Depressor labii inferiorisDepressor labii inferioris Depresses the lower lip as in Depresses the lower lip as in “irony”“irony”

Depressor anguli oris or Depressor anguli oris or TriangularisTriangularis

Depresses the angle of the Depresses the angle of the mouthmouth


BuccinatorBuccinator

Or Bugler’s or Trumpeter’s Or Bugler’s or Trumpeter’s musclemuscle

Draw the angle of the mouth Draw the angle of the mouth laterally and to press the laterally and to press the cheeks against the teeth cheeks against the teeth while chewing. Useful in while chewing. Useful in mastication, swallowing, mastication, swallowing, whistling, sucking, and whistling, sucking, and blowingblowing

MuscleMuscle OriginOrigin InsertionInsertion ActionAction Cranial Cranial NerveNerve

Orbicularis Orbicularis orisoris

Extrinsic Extrinsic fibers: fibers:

From From insertions insertions of of circumoral circumoral musclesmuscles

Intrinsic Intrinsic fibers:fibers:

From the From the incisive incisive fossae of fossae of the the mandible mandible and and maxillamaxilla

Pass Pass around the around the mouth mouth within the within the lips as a lips as a sphinctersphincter

Pass Pass obliquely obliquely forward forward and insert and insert into the into the skin of the skin of the liplip

CompresseCompresses the lips s the lips against the against the anterior anterior teeth, teeth, closes the closes the mouth, and mouth, and protrudes protrudes the lipsthe lips

VII - VII - zygomatic, zygomatic, buccal and buccal and mandibular mandibular branchesbranches

MuscleMuscle OriginOrigin InsertionInsertion ActionAction Cranial Cranial NerveNerve

PlatysmaPlatysma-thin, sub-thin, sub-

cutaneous cutaneous quadrilaterquadrilateral al muscular muscular sheet sheet covering covering the upper the upper part of the part of the chest, side chest, side of the neck of the neck and lower and lower part of the part of the face face

Skin and Skin and superficial superficial fascia of fascia of the the pectoral pectoral and deltoid and deltoid regionsregions

The fibers The fibers are are directed directed upward upward and and forward to forward to be inserted be inserted into the into the lower lower border of border of the the mandiblemandible

Retract Retract and and depress depress the angle the angle of the of the mouthmouth

VII - VII - cervical cervical branchbranch

Muscles of the External Ear

Muscles of the External Ear


Anterior auricularAnterior auricular Pulls the ear forwardPulls the ear forward

Posterior auricularPosterior auricular Pulls the ear backwardPulls the ear backward

Superior auricularSuperior auricular Pulls ear superiorlyPulls ear superiorly

COMMON FACIAL EXPRESSIONS

THE MUSCLES OF MASTICATION

The muscles of mastication includes:

1. Masseter2. Temporalis3. Medial Pterygoid4. Lateral Pterygoid

Functions of the Muscles of Functions of the Muscles of MasticationMastication

To move the mandible To secure then stabilize the mandibular

positions To determine the direction of mandibular

movements

The Masseter Muscle

The masseter muscle is a small quadrilateral muscle that covers most of the lateral aspect of the ramus of the mandible. Lying superficial to this muscle is a portion of the parotid gland, the parotid duct, the transverse facial artery, and the various branches of the facial nerve.

The Masseter Muscle

MuscleMuscle ActionActionMasseterMasseter

Superficial headSuperficial head ElevationElevation

(bilateral)(bilateral)

Ipsilateral excursionIpsilateral excursion

(unilateral)(unilateral)

ProtrusionProtrusion

(bilateral (bilateral

superficialsuperficial

head)head)

Deep headDeep head RetrussionRetrussion


The Masseter Muscle

The Temporalis Muscle

The temporalis muscle is fan-shaped, with the periphery of the fan attached to the side of the skull and the handle of the fan attached to the coronoid process of the mandible. The muscle is covered by a strong membranous sheet of fascia, which attaches superiorly to the superior temporal line. Below, the fascia splits to attach to the medial and lateral aspects of the zygomatic arch.

The Temporalis

MuscleMuscle ActionActionTemporalisTemporalis Elevation Elevation


Ipsilateral excursionIpsilateral excursion


RetrussionRetrussion


The Temporalis

The Medial Pterygoid

The medial and the lateral pterygoids are the occupants of the infratemporal fossa.

The medial pterygoid muscle is almost a mirror-like image of the masseter muscle. It is rhomboidal and runs practically in the same direction on the inner surface of the mandible.


MedialMedial

PterygoidPterygoidElevation Elevation


ProtrussionProtrussion


Contralateral excursionContralateral excursion

(unilateral(unilateral

The Lateral Pterygoid Muscle The lateral pterygoid is almost triangular

in shape with two distinct heads, inferior and superior head, each with contrasting functions. It is the only muscles of the four muscles of mastication to occupy primarily a horizontal position.

The Lateral Pterygoid

MuscleMuscle ActionActionLateral pterygoidLateral pterygoid

Inferior headInferior head

DepressionDepression


ProtrussionProtrussion


Contralateral excursionContralateral excursion


Lateral pterygoid Lateral pterygoid

Superior headSuperior head

ElevationElevation

-particularly during power -particularly during power strokestroke

The Lateral Pterygoid

The Accessory Muscles of Mastication Othes muscles

that active in mastication include the suprahyoid and infrahyoid muscles of the neck. Both groups of muscles are active in helping to depress the mandible.

Summary of Actions of the Muscles of Mastication

Elevation:

1. the right and left temporalis

2. the right and left masseter

3. the right and left medial pterygoid muscles

Summary of Actions of the Muscles of MasticationDepression:1. the inferior head

of the right and left lateral pterygoid muscles

2. the right and left suprahyoid muscles of the neck

3. the right and left infrahyoid muscles of the neck

Summary of Actions of the Muscles of MasticationProtrusion1. the right and

left lateral pterygoid muscles

2. the right and left medial pterygoid muscles

3. the right and left superficial heads of the masseter muscles

Summary of Actions of the Muscles of MasticationRetrussion1.The posterior

fibers of the right and left temporalis muscles

2. deep heads of the right and left masseter muscles

Summary of Actions of the Muscles of MasticationRight Lateral

Excursion

1. the right masseter

2. the right temporalis

3. the left medial pterygoid

4. the left lateral pterygoid

Summary of Actions of the Muscles of MasticationLeft Lateral

Excursion1. the left

masseter2. the left

temporalis3. the right

medial pterygoid

4. the right lateral pterygoid

The muscles of the eyeball

The Eye Muscles

- Composed of the 7 muscles of the eye- Lateral rectus is supplied by the

Abducent N.- Superior oblique is supplied by the

Trochlear N.- The rest is supplied by the Oculomotor

N.

The muscles of the tongue

The Muscles of the Tongue

Extrinsic muscles are responsible for changing position of the tongue.


GenioglossusGenioglossus Retract and depress the Retract and depress the tonguetongue

HyoglossusHyoglossus Depress the tongueDepress the tongue

StyloglossusStyloglossus Pull the tongue upwards and Pull the tongue upwards and backwardsbackwards

The Muscles of the Tongue

The Intrinsic Muscles:1. Superior and inferior longitudinal

muscles- Located close to the dorsum of the tongue- Shorten the length of the tongue and to curl

the tip of the tongue and back.2. Transverse muscles

- narrows the tongue.3. Vertical muscles

- flattens the tongue.

A Summary of the Actions of the Tongue1. Protrussion : genioglossus2. Retrussion : hyoglossus, styloglossus,

genioglossus3. Depression : genioglossus, hyoglossus4. Elevation : styloglossus5. Shortening : longitudinal intrinsic

fibers6. Narrowing : transverse intrinsic fibers7. Flattening : vertical intrinsic fibers

The muscles of the soft palate

Muscles of the Soft Palate



Palatopharyn-geusPalatopharyn-geus Elevates the pharynx and larynxElevates the pharynx and larynx

Closes the oropharyngeal Closes the oropharyngeal isthmusisthmus

PalatoglossusPalatoglossus Closes the oropharyngeal Closes the oropharyngeal isthmusisthmus

UvularUvular Raises the uvula to help seal oral Raises the uvula to help seal oral from nasal pharynxfrom nasal pharynx



Levator veli palatiniLevator veli palatini Elevates palate during Elevates palate during swallowing, yawningswallowing, yawning

Tensor veli palatiniTensor veli palatini Tenses the palate and opens Tenses the palate and opens the mouth of auditory tube the mouth of auditory tube during swallowing and yawningduring swallowing and yawning

the musculature of the head

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