Muscle Origins, Insertions, Actions - Head & Neck
Terms
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- Longus colli
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Origin: lower anterior vertebral bodies and transverse processes
Insertion: anterior vertebral bodies and transverse processes several segments above
Action: flexes the head and neck - Longus capitis
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Origin: upper anterior vertebral bodies and transverse processes
Insertion: anterior vertebral bodies and transverse processes several segments above
Action: flexes the head and neck - Rectus capitis anterior
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Origin: anterior base of the transverse process of the atlas
Insertion: occipital bone anterior to foramen magnum
Action: flexes the head - Rectus capitis lateralis
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Origin: transverse process of the atlas
Insertion: jugular process of the occipital bone
Action: bends the head laterally - Anterior scalene
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Attachment A: anterior tubercles of transverse processes of C3-C6
Attachment B: 1st rib
Action:
if transverse process fixed:
elevates the ribs for respiration
if ribs fixed:
rotates to side opposite of contraction
laterally flexes to the contracted side
bilaterally flexes the neck - Middle scalene
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Attachment A: transverse processes of all cervical vertebrae
Attachment B: 1st rib (behind anterior scalene)
Action:
if transverse process fixed:
elevates the ribs for respiration
if ribs fixed:
rotates to side opposite of contraction
laterally flexes to the contracted side
bilaterally flexes the neck - Posterior scalene
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Attachment A: posterior tubercles of transverse processes of C5 & C6
Attachment B: 2nd and/or 3rd rib
Action:
if transverse process fixed:
elevates the ribs for respiration
if ribs fixed:
rotates to side opposite of contraction
laterally flexes to the contracted side
bilaterally flexes the neck - Sternocleidomastoid
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Origin: (two heads)
manubrium of sternum
medial portion of clavicle
Insertion: mastoid process of temporal bone
Action:
rotates to side opposite of contraction
laterally flexes to the contracted side
bilaterally flexes the neck - Platysma
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Origin: subcutaneous skin over delto-pectoral region
Insertion: invests in the skin widely over the mandible
Action:
depress mandible and lower lip
tenses the skin over the lower neck - Occipitalis (2 bellies)
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Origin:
lateral 2/3 of superior nuchal line
external occipital protuberance
Insertion: galea aponeurosis, over the occipital bone
Action: draws back the scalp to raise the eyebrows and wrinkle the brow - Frontalis (2 bellies)
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Origin: galea aponeurosis, anterior to the vertex
Insertion: skin above the nose and eyes
Action: draws back the scalp to raise the eyebrows and wrinkle the brow - Orbicularis oculi
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Origin:
orbital portion: nasal process of frontal bone
palpebral portion: palpebral ligament
lacrimal portion: lacrimal crest of lacrimal bone
Insertion: circumferentially around orbit meeting in palpebral raphe
Action: powerfully closes the eye - Orbicularis oris
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Origin:
alveolar border of maxilla
lateral to midline of mandible
Insertion:
circumferentially around mouth
blends with other muscles
Action:
closes the lips
protrudes the lips - Zygomaticus minor
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Origin: zygomatic bone, posterior to maxillary-zygomatic suture
Insertion: skin of the upper lip
Action: elevates the upper lip - Zygomaticus major
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Origin: anterior to zygomatic-temporal suture
Insertion: modiolus (angle of the mouth)
Action: lifts and draws back the angle(s) of the mouth (as in smiling) - Buccinator
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Origin:
posterior alveolar process of maxilla
posterior alveolar process of mandible
along the pterygomandibular raphe
Insertion: modiolus
Action: compresses the cheek(s) - Masseter
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Origin:
Superficial:
zygomatic process of the maxilla
inferior border of zygomatic arch
Intermediate: inner surface of zygomatic arch
Deep: posterior aspect of inferior border of zygomatic arch
Insertion:
Superficial:
angle of mandible
lateral surface of mandibular ramus
Intermediate: ramus of mandible
Deep:
superior ramus of mandible
coronoid process of mandible
Action:
closes the lower jaw (clenches the teeth)
may deviate mandible to opposite side of contraction - Superior oblique
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Origin: body of sphenoid
Insert: upper lateral quadrant of the posterior half of the sclera (via the trochlea, as a pulley)
Action:
depress
medially rotates
abducts the eye - Inferior oblique
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Origin: orbital surface of maxilla
Insert: lower lateral quadrant of the posterior half of the sclera (via the suspensory ligament, as a pulley)
Action:
elevates
laterally rotates
abducts the eye