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Muscle Origin and Insertions 1
Origin, insertion, action
26
Anatomy
11/18/2008

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Term
Epicranius
Definition
-Bipartite muscle consisting of the frontal and occipital bellies (connected by a cranial aponeurosis, the galea aponeurotica; the alternate actions of these two muscles pull scalp forward adn backward
Term
Frontal Belly
Definition

Origin: Galea

Insertion: Skin of eyebrow and root of nose

Action: w/ aponeurosis fixed, raises the eyebrows (surprise look); wrinkles forehead skin horizontally

Term
Occipital Belly
Definition

Origin: Occipital and temporal bones

Insertion: Galea aponeurotica

Action: Fixes aponeurosis and pulls scalp posteriorly

Term
Corrugator Supercilii
Definition

Origin: Arch of frontal bone above nasal bone. Insertion: Galea aponeurotica

Action: Draws eyebrows together and inferiorly; wrinkles skin of forehead vertically (as in frowning)

Term
Orbicularis Oculi
Definition

Origin: Frontal and maxillary bones and ligaments around orbit

Insertion: Tissue of eyelid

Action: protects eyes from intense light and injury; various parts can be activated individually; produces blinking, squinting, & draws eyebrows inferiorly

Term
Zygomaticus
Definition

Origin: zygomatic bone

Insertion: skin & muscle at corner of mouth

Action: Raises lateral corners of mouth upward (smiling muscle) :)

Term
Risorius
Definition

Origin: Lateral fascia associated w/ masseter muscle Insertion: Skin at angle of mouth

Action: Draws corner of lip laterally; tenses lips; synergist of zygomaticus

Term
Levator labii superioris
Definition

Origin: zygomatic bone and infraorbital margin of maxilla

Insertion: Skin and muscle of upper lip

Action: opens lip; raises and furrows the upper lip

Term
Depressor labii inferioris
Definition

Origin: Body of mandible lateral to its midline Insertion: Skin & muscle of lower lip

Action: draws lower lip inferiorly (as in a pout) :(

Term
Depressor labii inferioris
Definition

Origin: Body of mandible lateral to its midline Insertion: Skin & muscle of lower lip

Action: draws lower lip inferiorly (as in a pout) :(

Term
Depressor Anguli oris
Definition

Origin: Body of mandible below incisors

 

Insertion: Skin and muscle at angle of mouth below insertion of zygomaticus

 

Action: Zygomaticus antagonists; draws corners of mouth downward and laterally (as in Greek tragedy mask)

Term
Depressor Anguli oris
Definition

Origin: Body of mandible below incisors

 

Insertion: Skin and muscle at angle of mouth below insertion of zygomaticus

 

Action: Zygomaticus antagonists; draws corners of mouth downward and laterally (as in Greek tragedy mask)

Term
Orbicularis oris
Definition

Origin: Arises indirectly from maxilla & mandible; fibers blended w/ fibers of other facial muscles associated w/ lips.

 

-Insertion: Encircles mouth; inserts into muscle and skin @ angles of mouth.

 

-Action: Closes lips; purses and protrudes lips; kissing and whistling muscle.

Term
Mentalis
Definition

Origin: Mandible below incisors

-Insertion: skin of chin -

Action: Protrudes lower lip; wrinkles chin

Term
Buccinator
Definition

-Origin: Molar region of maxilla & mandible

 

-Insertion: Orbicularis oris

 

-Action: Draws corner of mouth laterally; compresses cheek (as in whistling and sucking); trampoline-like action of buccinator muscles helps hold food b/t teeth during chewing; well developed in nursing infants.

Term
Platysma
Definition

-Origin: Fascia of chest (over pectoral M and deltoid)

 

-Insertion: Lower margin of mandible, and skin & muscle at corner of mouth

 

-Action: Helps dress mandible ; pulls lower lip back and down, i.e., produces downward sag of mouth; tenses skin of neck (e.g during shaving)

Term
Masseter
Definition

-Origin: Zygomatic arch and maxilla

 

-Insertion: Angle and ramus of mandible

 

-action: prime mover of jaw closure; elevates mandible

Term
Temporalis
Definition

-Origin: Temporal fossa -

 

Insertion: Coronoid process of mandible via a tendon that passes deep to zygomatic arch -

 

Action: Closes jaw; elevates and retracts mandible; synergist of pterygoids (see below) in side-to-side movements; maintains position of the mandible at rest

Term
Medial Pterygoid
Definition

-Origin: Medial surface of lateral pterygoid plate of sphenoid bone, maxilla & palatine bone. -

 

Insertion: Medial surface of mandible near it angle -

 

Action: Synergist of temporalis and masseter muscles in elevation of the mandible; acts w/ the lateral pterygoid muscle to protrude mandible and to promote side-to-side (grinding) movements

Term
Lateral Pterygoid
Definition

-Origin: Greater wing and lateral pterygoid plate of sphenoid bone -

 

Insertion: Condyle of mandible and capsule of tempromandibular joint

 

-Action: Protrudes mandible (pulls it anteriorly); provides forward sliding and side-to-side side grinding movements of lower teeth

Term
Genioglossus
Definition

-Origin: Internal surface of mandible near symphysis

 

-Insertion: Inferior aspect of the tongue and body of the hyoid bone. -

 

Action: Primarliy protrudes tongue, but can depress or act in concert w/ other extrinsic muscles to retract tongue.

Term
Hypoglossus
Definition

-Origin: body of greater horn of hyoid bone.

 

-Insertion: Inferolateral tongue. -

 

Action: Depresses tongue and draws it sides downward.

Term
Styloglossus
Definition

-Origin: Styloid process of temporal bone -

 

Insertion: Inferolateral tongue -

 

Action: Retracts (and elevates) tongue

Term
Digastric
Definition

-Origin: Lower margin of mandible (anterior belly) and mastoid process of the temporal bone (posterior belly) -

 

Insertion: By a connective tissue loop to hyoid bone. -

Action: Acting in concert, the digastrics muscles elevate hyoid bone and steady it during swallowing and speech; acting from behind, they open mouth and depress mandible.

Term
Stylohyoid
Definition

-Origin: Styloid process of temporal bone -

 

Insertion: Hyoid bone -

 

action: Elevates and retracts hyoid, thereby elongating floor of mouth during swallowing.

Term
Mylohyoid
Definition

-Origin: Medial surface of mandible -

 

Insertion: Hyoid bone and median raphe -

 

Action: Elevates hyoid bone and floor of mouth, enabling tongue to exert backward and upward pressure that force3s food bolus into pharynx.