Download - Muscles that Act on the Axial Skeleton
Muscles that
Act on the
Axial Skeletonby Carone Learning
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Muscles that Act on the Axial Skeleton
Axial Skeleton
The axial skeleton is part of the
skeletal system that includes the skull,
ribcage, and vertebral column.
Muscles of the axial skeleton perform
the following functions:
• Facial expressions
• Chewing
• Ventilation
• Control the neck
Axial Skeleton
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The following muscles control facial
expressions:
• Epicranius
• Orbicularis oris
• Buccinator
Muscles that Act on the Axial Skeleton
©Life Art
Facial Expressions
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Epicranius
The epicranius is actually composed of
two muscles that are separated by the
galea aponeurotica. The galea
aponeurotica is a broad sheath of
connective tissue.
The two muscles that combine to form
the epicranius are:
1. Frontalis
2. Occipitalis
Muscles that Act on the Axial Skeleton
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Frontalis
Frontalis- elevates the eyebrow and
wrinkles the forehead
• Origin: galea aponeurotica
• Insertion: skin of eyebrow
Muscles that Act on the Axial Skeleton
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Occipitalis
Occipitalis- moves scalp backwards
• Origin: occipital bone and mastoid
process of the temporal bone
• Insertion: galea aponeurotica
Muscles that Act on the Axial Skeleton
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Orbicularis Oris
Orbicularis oris- closes the lips, forms
words, and puckers the lips. This is your
kissing muscle!
• Origin: fascia surrounding lips
• Insertion: skin of the lips
Muscles that Act on the Axial Skeleton
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Buccinator
Buccinator- compresses the cheeks.
You use this muscle to suck and blow
air.
• Origin: maxilla and mandible
• Insertion: orbicularis oris
Muscles that Act on the Axial Skeleton
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Mastication
The movements of chewing and biting
are known as mastication.
The muscles that aid with mastication
include:
• Temporalis
• Masseter
• Medial and lateral pterygoid
Muscles that Act on the Axial Skeleton
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Temporalis
Temporalis- closes the mouth by
elevating the mandible
• Origin: temporal fossa of the
zygomatic bone
• Insertion: coronoid process of
mandible
Muscles that Act on the Axial Skeleton
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Masseter
Masseter- closes the mouth by
elevating the mandible. It is superficial
so you can see this muscle as you bite
down.
• Origin: zygomatic arch
• Insertion: lateral ramus of mandible
Muscles that Act on the Axial Skeleton
©Life Art
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Pterygoid
Medial and lateral pterygoid- elevates
and protracts the mandible. They also
move the mandible laterally.
• Origin: sphenoid bone
• Insertion: mandible
Muscles that Act on the Axial Skeleton
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Prime Movers of the Neck
Two prime movers of the neck are:
1. Sternocleidomastoid
2. Splenius capitis
Muscles that Act on the Axial Skeleton
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Sternocleidomastoid
Sternocleidomastoid- runs along the
side of the neck. When one contracts,
the head turns to the opposite side. For
example, if the right sternocleidomastoid
contracts, the head pivots to the left.
When both sides contract, the head is
pulled forward and down.
• Origin: sternum and clavicle
• Insertion: mastoid process of
temporal bone
Muscles that Act on the Axial Skeleton
©Life Art
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Splenius Capitis
Splenius capitis- extends the head. It
also laterally flexes and rotates head at
the same time.
• Origin: inferior half of ligamentum
nuchae (C3-C6) and spinous process
of C7-T3
• Insertion: superior nuchal line of
occipital bone and mastoid process
of temporal bone
Muscles that Act on the Axial Skeleton
©Life Art
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Ventilation
Ventilation, or breathing, is moving air
into and out of the lungs.
Muscles that aid with ventilation include:
• Diaphragm
• External intercostals
• Internal intercostals
Muscles that Act on the Axial Skeleton
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Diaphragm
Diaphragm- pulls the central tendon
inferiorly and increases the vertical
dimensions of the thorax. During
inhalation, or breathing in, the
diaphragm contracts and makes more
room in the chest cavity. During
exhalation, or breathing out, the
diaphragm recoils passively upwards.
• Origin: xiphoid process of the
sternum, costal cartilages of lower
ribs, and lumbar vertebrae
• Insertion: central tendon of the
diaphragm
Muscles that Act on the Axial Skeleton
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External Intercostals
External intercostals- elevates and
draws ribs together during restful
breathing. During inhalation, the external
intercostals move the ribs up and out to
make more room in the chest cavity.
During exhalation, the ribs passively
return to their starting position.
• Origin: inferior border of a rib
• Insertion: superior border of the rib
below
Muscles that Act on the Axial Skeleton
©Life Art
© Carone Learning
Internal Intercostals
Internal intercostals- draws the ribs
together and depresses the thorax
during forceful breathing. This occurs
during exercise when your body forces
exhalation.
• Origin: superior border of a rib
• Insertion: inferior border of the rib
above
Muscles that Act on the Axial Skeleton
©Life Art
© Carone Learning
Muscles that Act on the Axial Skeleton
Functions
Muscles of the axial skeleton perform
the following functions:
• Facial expressions
• Chewing
• Ventilation
• Control the neck
©Life Art
© Carone Learning
Facial Expressions
The following muscles control facial
expressions:
• Epicranius
• Orbicularis oris
• Buccinator
Muscles that Act on the Axial Skeleton
©Life Art
© Carone Learning
Mastication
The muscles that aid with mastication,
or chewing, include:
• Temporalis
• Masseter
• Medial and lateral pterygoid
Muscles that Act on the Axial Skeleton
©Life Art
© Carone Learning
Prime Movers
Two prime movers of the neck are:
1. Sternocleidomastoid
2. Splenius capitis
Muscles that Act on the Axial Skeleton
©Life Art
© Carone Learning
Ventilation
Muscles that aid with ventilation, or
breathing, include:
• Diaphragm
• External intercostals
• Internal intercostals
Muscles that Act on the Axial Skeleton
©Life Art
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