Outline 7 (part 2 – muscle origins, insertions, and actions)
Frontalis – frun-TAY-lis
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Origin: Galea aponeurotica (a broad tendon sheet that connects to the occipitalis muscle)
Insertion: Subcutaneous tissue of eyebrows
Action: Elevates eyebrows, draws scalp forward and wrinkles skin of the forehead
Occipitalis – oc-SIP-ih-TAY-lis
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Origin: Superior nuchal line (ridge running horizontally from either side of the external occipital
protuberance) and temporal bone
Insertion: Galea aponeurotica
Action: Retracts scalp, fixes galea aponeurotica so frontalis can act on eyebrows
Orbicularis Oculi– or BIC you LERR is
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OC you lye
Origin: Lacrimal bone, adjacent regions of frontal bone and maxilla, medial angle of eyelids
Insertion: Upper and lower eyelids, skin around margin of orbit
Action: Sphincter of the eyelids, closes eyes in blinking, squinting, and sleeping
Zygomaticus minor– ZY go MAT ih cus minor
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Origin: Zygomatic bone
Insertion: Muscles of upper lip
Action: Elevates upper lip, exposes upper teeth in smiling or sneering
Levator Labii Superioris– le VAY tur LAY bee eye
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soo PEER ee OR is
Origin: Zygomatic bone and maxilla near inferior margin of orbit
Insertion: Muscles of upper lip
Action: Elevates and everts upper lip in sad, sneering, or serious expressions
Nasalis– nay ZAIL is
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Origin: Maxilla just lateral to nose
Insertion: Bridge and alar cartilages of nose
Action: Widens nostrils; narrows internal air passage within nose
Orbicularis Oris– or BIC you LERR is OR is
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Origin: Modiolus of mouth (point at corner of the mouth where 8 muscles meet)
Insertion: submucosa and dermis of lips
Action: Encircles mouth, closes lips, protrudes lips as in kissing
Zygomaticus major– ZY go MAT ih cus major
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Origin: Zygomatic bone
Insertion: Superolateral angle of mouth
Action: Draws angle of mouth upward and laterally as in laughing
Buccinator– BUC sin AY tur
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Origin: Alveolar processes on lateral surfaces of maxilla and mandible
Insertion: Orbicularis oris; submucosa of cheek and lips
Action: Compresses cheek against teeth and gums; directs food between teeth for chewing;
retracts cheek from teeth when mouth is closing to prevent biting cheek; used in drinking from a
straw and suckling by infants
Risorius– rih SOR ee us
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Origin: Zygomatic arch, fascia near ear
Insertion: Modiolus of mouth
Action: Draws angle of mouth laterally in expressions of laughing, horror, or disdain
Triangularis (or Depressor Anguli Oris)
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Origin: Inferior margin of mandibular body
Insertion:Modiolus of mouth
Action: Draws angle of mouth laterally and downward in opening mouth or sad expressions
Depressor Labii Inferioris
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Origin: Near mental protuberance
Insertion: Skin and mucosa of lower lip
Action: Draws lower lip downward and laterally in chewing and expressions of melancholy or
doubt
Mentalis – men TAY lis
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Origin: Mandible near inferior incisors
Insertion: Skin o f chin at mental protuberance
Action: Elevates and protrudes lower lip in drinking, pouting, and expressions of doubt or disdain
Temporalis – TEM po RAY liss
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Origin: Temporal lines (which are actually curved lines on the parietal bone) and temporal fossa
of cranium
Insertion: Coronoid process and anterior border of mandibular ramus
Action: Elevation, retraction, and lateral and medial excursion of the mandible
Masseter – ma See tur
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Origin: Zygomatic arch
Insertion: Lateral surface of mandibular ramus and angle
Action: Elevation of the mandible, with smaller roles in protraction, retraction, and medial
excursion
Sternocleidomastoid – STIR no CLY do MAST oyd
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Origin: manubrium of sternum, medial one-third of clavicle
Insertion: mastoid process
Action: Rotating head to left and right. Bilateral action draws head straight forward and down.
Stylohyoid –
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Origin: Styloid process of temporal bone
Insertion: Hyoid bone
Action: Elevates and retracts hyoid, elongating floor of the mouth
Digastric (posterior belly)–
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Origin: Mastoid notch of temporal bone
Insertion: Hyoid bone
Action: Depresses mandible when hyoid is fixed; opens mouth widely; elevates hyoid when
mandible is fixed
Digastric (anterior belly)–
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Origin: Digastric fossa of mandible
Insertion: Hyoid bone
Action: Depresses mandible when hyoid is fixed; opens mouth widely; elevates hyoid when
mandible is fixed
Mylohyoid–
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Origin: Mylohyoid line near inferior margin of mandible
Insertion: Hyoid bone
Action: Spans mandible from side to side and forms floor of mouth; elevates floor of mouth in
initial stage of swallowing
Hyoglossus– HI oh GLOSS us
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Origin: Body and greater horn of hyoid bone
Insertion: Lateral and inferior surfaces of tongue
Action: Depresses tongue
Omohyoid–
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Origin: Superior border of scapula
Insertion: Hyoid bone
Action: Depresses hyoid after it has been elevated
Sternohyoid–
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Origin: Manubrium of sternum, medial end of clavicle
Insertion: Hyoid bone
Action: Depresses hyoid after it has been elevated
Sternothyroid–
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Origin: manubrium of sternum
Insertion: thyroid cartilage of larynx
Action: Depresses larynx after it has been elevated in swallowing and vocalization; aids in
singing low notes
Thyrohyoid–
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Origin: Thyroid cartilage of the larynx
Insertion: Hyoid bone
Action: Depresses hyoid; with hyoid fixed, elevates larynx and aids in singing high notes
Scalenes (anterior, middle, & posterior) –
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Origin: Transverse processes of cervical vertebrae
Insertion: Ribs 1-2
Action: Flexion or rotation of neck; If spine is fixed, scalenes elevate ribs 1-2 and aid in breathing
External Intercostals – IN tur COSS tuls
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Origin: Inferior margins of ribs 1-11
Insertion: Superior margin of next lower rib
Action: Elevating and protracting ribs to increase the size of the thoracic cavity, causing inflow of
air
Internal Intercostals – IN tur COSS tuls
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Origin: Superior margins and costal cartilages of ribs 2-12; margin of sternum
Insertion: Inferior margin of next higher rib
Action: Depresses and retracts the ribs, compressing the thoracic cavity and expelling air (in
forceful expiration)
External Abdominal Oblique –
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Origin: Ribs 5-12
Insertion: Anterior half of iliac crest, pubic symphysis, and superior margin of pubis
Action: Supports abdominal viscera, stabilizes vertebral column during lifting, maintains posture,
compresses abdominal organs to aid in forceful expiration and to aid in childbirth, urination, and
defecation. Also, unilateral contraction causes rotation of waist
Rectus Abdominis –
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Origin: Pubic symphysis and superior margin of pubis
Insertion: Xiphoid process, costal cartilages 5-7
Action: Flexes lumbar region of vertebral column, flexes waist as in fending forward or doing situps; stabilizes pelvic region during walking, compresses abdominal viscera
Internal Abdominal Obliques –
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Origin: Inguinal ligament, iliac crest, and thoracolumbar fascia
Insertion: Ribs 10-12, costal cartilages 7-10, pubis
Action: Same as external oblique except that unilateral contraction causes ipsilateral rotation of
waist
Transverse Abdominus –
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Origin: Inguinal ligament, iliac crest, thoracolumbar fascia, costal cartilages 7-12
Insertion: Linea alba, pubis, aponeurosis of internal oblique
Action: Compresses abdominal contents but does not contribute to movements of the vertebral
column
Erector Spinae – eh REC tur SPY nee
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Origin: Nuchal ligament, ribs 3-12, thoracic and lumbar vertebrae, median and lateral sacral
crests, thoracolumbar fascia
Insertion: Mastoid process, cervical and thoracic vertebrae, and all ribs
Action: Maintains posture, straightens spine after one bends at the waist, arches back; laterally
flexes vertebral column
Serratus Posterior Inferior –
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Origin: T11-L2 vertebrae
Insertion: Lower body of 9th through 12 ribs
Action: Draw the lower ribs backward and downward to assist in rotation and extension of the
trunk
Splenius Capitis –
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Origin: Spinous processes of T1-3
Insertion: Lower occipital bone
Action: Extends and rotates cervical spine
Quadratus Lumborum –
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Origin: Internal lip of the iliac crest
Insertion: Lower border of the last rib
Action: Lateral flexion of vertebral column; extension of lumbar vertebral column
Trapezius –
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Origin: External occipital protruberance and spinous processes of C7 - T12 vertebrae
Insertion: Lateral third of clavicle, and acromion and spine of scapula
Action: Elevates, retracts and rotates scapula
Rhomboid Major –
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Origin: Spinous processes of T2 - T5 vertebrae
Insertion: Medial border of scapula from level of spine to inferior angle
Action: Retract scapula; fix scapula to thoracic wall
Rhomboid Minor –
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Origin: Spinous processes of C7 and T1 vertebrae
Insertion: Medial border of scapula from level of spine
Action: Retract scapula and rotate it to depress glenoid cavity; fix scapula to thoracic wall
Pectoralis Major –
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Origin: Medial half of clavicle; lateral margin of sternum; costal cartilages 1-7
Insertion: Lateral lip of intertubercular sulcus of humerus
Action: Flexes, adducts, and medially rotates humerus, as in climbing or hugging
Levator Scapulae – leh VAY tur SCAP you lee
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Origin: Transverse processes of vertebrae C1-C4
Insertion: Superior angle to medial border of scapula
Action: Elevates scapula if cervical vertebrae are fixes; flexes neck laterally if scapula is fixed,
retracts scapula and braces shoulder; rotates scapula and depresses apex of shoulder
Pectoralis Minor – PECK to RAY lis
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Origin: Ribs 3-5 and overlying fascia
Insertion: Coracoid process of scapula
Action: Draws scapula laterally and forward around chest wall, protracting shoulder as in
reaching out for a door handle. Rotates scapula and depresses apex of shoulder, as in reaching
down to pick up a suitcase
Subscapularis – SUB SCAP you LERR iss
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Origin: Subscapular fossa of scapula
Insertion: Lesser tubercle of humerus; anterior suface of joint capsule
Action: Modulates action of deltoid, preventing humeral head from sliding upward as arm is
abducted
Latissimus Dorsi – la TISS ih mus DOR sye
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Origin: Vertebrae T7-L5; lower three or four ribs; iliac crest; thoracolumbar fascia
Insertion: Floor of intertubercular sulcus of humerus
Action: Adducts and medially rotates humerus; extends shoulder joint; produces backswing of
arm in actions like walking and bowling
Supraspinatus – SOO pra spy NAY tus
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Origin: Supraspinous fossa of scapula
Insertion: Greater tubercle of humerus
Action: Aids deltoid in abduction of arm; resists downward slippage of humeral head when arm is
relaxed or when carrying weight
Infraspinatus – IN fra spy NAY tus
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Origin: Infraspinous fossa of scapula
Insertion: Greater tubercle of humerus
Action: Modulates action of deltoid; preventing humeral head from sliding upward as arm is
abducted; adducts and laterally rotates humerus
Teres minor – TERR eez
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Origin: Superior part of lateral border of scapula
Insertion: Inferior facet on greater tubercle of humerus
Action: Laterally rotate arm
Teres Major– TERR eez
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Origin: Dorsal surface of inferior angle of scapula
Insertion: Intertubercular sulcus of humerus
Action: Extends and medially rotates humerus
Deltoid–
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Origin: Lateral third of clavicle, acromion, and spine of scapula
Insertion: Deltoid tuberosity of humerus
Action: Anterior part flexes and medially rotates arm; middle part abducts arm; posterior part
extends and laterally rotates arm
Coracobrachialis– COR uh co BRAY kee AL iss
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Origin: Coracoid process of scapula
Insertion: Middle third of medial surface of humerus
Action: Flexes and medially rotates arm
Biceps brachii– BY seps BRAY kee eye
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Origin: Short head: tip of coracoid process of scapula; long head above glenoid cavity of scapula
Insertion: Radial tuberosity
Action: Supinates forearm and, when it is supine, flexes forearm
Brachialis– BRAY kee AL iss
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Origin: Distal half of anterior surface of humerus
Insertion: Coronoid process of ulna
Action: Major flexor of forearm – flexes forearm in all position
Triceps Brachii–
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Origin: Long head: inferior margin of glenoid cavity; Lateral head: posterior surface of proxam
end of humerus; medial head: posterior surface of entire humeral shaft
Insertion: Olecranon
Action: Extends elbow; long head extends and adducts humerus
Brachioradialis– BRAY kee oh RAY dee AL iss
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Origin: Lateral supracondylar ride of humerus
Insertion: Lateral surface of radius near styloid process
Action: Flexes elbow
Anconeus– an CO nee us
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Origin: Lateral epicondyle of humerus
Insertion: Olecranon and posterior surface of ulna
Action: Extends elbow; may help control ulnar movement during pronation