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Muscles of the Head

• Two groups– Muscles of facial expression– Muscles of mastication and tongue movement

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Muscles of Facial Expression

• Insert into skin

• Important in nonverbal communication

• All innervated by cranial nerve VII (facial nerve)

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Muscles of Facial Expression: The Scalp

• Epicranius (occipitofrontalis)– Bipartite muscle consisting of

• Galea aponeurotica—cranial aponeurosis connecting two bellys

• Frontal belly; occipital belly – Have alternate actions; pull scalp forward and backward

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Muscles of Facial Expression: The Face

• Corrugator supercilii

• Zygomaticus• Risorius• Levator labii

superioris• Depressor labii

inferioris

• Depressor anguli oris

• Orbicularis oris• Mentalis• Buccinator• Platysma

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Figure 10.7b Lateral view of muscles of the scalp, face, and neck.

Epicranialaponeurosis

Frontalbelly

Epicranius

Occipitalbelly

Temporalis

MasseterSternocleidomastoidTrapezius

Spleniuscapitis

PlatysmaDepressor anguli oris

Depressorlabii inferioris

MentalisOrbicularis orisRisoriusBuccinator

Zygomaticusminor and major

Levator labiisuperioris

Orbicularis oculiCorrugator supercilii

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Muscles of Mastication

• Four pairs involved in mastication; all innervated by cranial nerve V (trigeminal nerve)– Prime movers of jaw closure

• Temporalis and masseter

– Chewing role - holds food between teeth• Buccinator

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Figure 10.8a Muscles promoting mastication and tongue movements.

Orbicularisoris

Buccinator

Temporalis

Masseters

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PLAYPLAY A&P Flix™: Temporalis

PLAYPLAY A&P Flix™: Masseter

PLAYPLAY A&P Flix™: Buccinator

Muscles of Mastication and Tongue Movement

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Muscles of Tongue Movement

• Three muscles anchor and move tongue– Genioglossus– Hyoglossus– Styloglossus

• All innervated by cranial nerve XII - hypoglossal nerve

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Figure 10.8c Muscles promoting mastication and tongue movements.

Styloid process

Styloglossus

Stylohyoid

Hyoglossus

Hyoid bone

Thyrohyoid

Tongue

Genioglossus

Thyroid cartilage

Geniohyoid

Mandibular symphysis

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Animation: Rotating face

Animation: Rotating head

Infrahyoid Muscles of the Anterior Neck and Throat

PLAYPLAY

PLAYPLAY

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Muscles of the Neck and Vertebral Column

• Two functional groups– Muscles that move head– Muscles that extend trunk and maintain

posture

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Muscles of the Neck and Vertebral Column: Head Movement

• Sternocleidomastoid—major head flexor

• Sternocleidomastoid -- lateral head movements

• Splenius capitis - head extension, rotation, and lateral bending

• Semispinalis capitis—synergist with sternocleidomastoid

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Figure 10.10a Muscles of the neck and vertebral column that move the head and trunk.

1st cervicalvertebra

Sternocleido-mastoid

Base ofoccipital bone

Mastoidprocess

Anterior

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Figure 10.10b Muscles of the neck and vertebral column that move the head and trunk.

Mastoid process

Spleniuscapitis

Posterior

Spinousprocessesof thevertebrae

Spleniuscervicis

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Figure 10.10c Muscles of the neck and vertebral column that move the head and trunk.

Sternocleidomastoid(cut)

Platysma (cut)

Internal jugular vein

Omohyoid

Sternohyoid

Sternothyroid

Sternocleidomastoid

Pectoralis major

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PLAYPLAY A&P Flix™: Semispinalis capitis

PLAYPLAY A&P Flix™: Splenius capitis

Muscles of the Neck and Vertebral Column: Head Movement

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Mastoid processof temporal bone

Longissimus capitis

Iliocostalis cervicisLongissimus cervicis

Iliocostalis thoracis

Longissimus thoracisSpinalis thoracis

Erectorspinae

Iliocostalislumborum

External oblique

IliocostalisLongissimusSpinalis

LigamentumnuchaeSemispinaliscapitis

Semispinaliscervicis

Semispinalisthoracis

Quadratuslumborum

Multifidus

Figure 10.10d Muscles of the neck and vertebral column that move the head and trunk.