Lab Activity 11: Group I

Muscles

Martini Chapter 11

Portland Community CollegeBI 231

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Origin and Insertion

• Origin: The place where the fixed end attaches to a bone, cartilage, or connective tissue.

• Insertion: The site where the movable end attaches to another structure.

MUSCLES OF THE HEAD

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Frontalis

• Origin: Epicranial aponeurosis

• Insertion: Skin over forehead

• Action: Elevates eyebrows and wrinkles skin of forehead

Epicranial Aponeurosis

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Occipitalis

• Origin: Occipital and temporal bones

• Insertion: Epicranial aponeurosis

• Action: Fixes epicranial aponeurosis and pulls scalp posteriorly

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Orbicularis Oculi

• Origin: Medial orbital margin and zygomatic bone

• Insertion: Skin surrounding eye

• Action: Closes eyelids and depresses skin of forehead

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Temporalis

• Origin: Temporal fossa

• Insertion: Coronoid process of mandible

• Action: Elevates and retracts mandible

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Masseter

• Origin: Zygomatic process and arch

• Insertion: Angle and ramus of mandible

• Action: Elevates mandible

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Orbicularis Oris

• Origin: By muscular skips to surround muscles

• Insertion: Muscles interlace to surround mouth

• Action: Closes and purses lips

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• Origin: Zygomatic arch

• Insertion: Corner of mouth

• Action: Elevates corner of mouth

Zygomaticus Major

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• Origin: Fascia of masseter

• Insertion: Corner of mouth

• Action: Draws corner of mouth laterally

Risorius

SUPERFICIAL MUSCULATURE OF THE NECK

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• Origin: Medial tip of suprascapular notch

• Insertion: Body of

hyoid bone

• Action: Depresses hyoid bone

Omohyoid

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• Origin: Posterior surface of manubrium, and medial clavicle

• Insertion: Hyoid bone

• Action: Depresses hyoid bone

Sternohyoid

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• Origin: Mylohyoid line of mandible

• Insertion: Hyoid bone • Action: Elevates

hyoid bone and floor of mouth, depresses mandible

Mylohyoid

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• Origin: Lower border of mandible near midline

• Insertion: Intermediate tendon on the hyoid bone

• Action: Elevates hyoid bone and base of tongue, depresses mandible

DigastricAnterior Belly

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• Origin: Mastoid notch of temporal bone

• Insertion: Intermediate tendon on the hyoid bone

• Action: Moves hyoid bone back

DigastricPosterior Belly

MUSCLES OF THE NECK & BACK

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• Origin: Manubrium and medial third of clavicle

• Insertion: Mastoid process

• Action: Rotates head to opposite side, extends head, and flexes vertebral column

Sternocleidomastoid

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Trapezius

• Origin: External occipital protuberance, superior nuchal line and spinous process of C7-T12

• Insertion: Anterior border of scapular spine, acromion process, lateral third of clavicle

• Action: Elevates, adducts, and depresses scapula

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Latissimus Dorsi

• Origin: Spinous processes of lower 6 thoracic vertebrae, thoracolumbar fascia, crest of ilium

• Insertion: Intertubercular groove of humerus

• Action: Extends, rotates humerus medially, draws shoulder down and backward

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• Origin: Transverse processes of C1-4

• Insertion: Superior angle spine of scapula

• Action: Elevates scapula

Levator Scapula

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• Origin: Spinous process of T1-5 and supraspinous ligament

• Insertion: Medial border below spine of scapula

• Action: Adducts scapula and performs downward rotation

Rhomboid Major

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• Origin: Spinous process of C7-T1

• Insertion: Medial border of scapula at base of spine

• Action: Adducts scapula and performs downward rotation

Rhomboid Minor

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• Origin: Lateral surface of upper 8 ribs

• Insertion: Anterior lip of medial border of scapula

• Action: Holds scapula to chest wall, medially rotates scapula in abducting or extending humerus

Serratus Anterior

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• Origin: Sacrum, iliac crest, spinous processes of lumbar vertebrae and T11,12

• Insertion: Angles of the ribs. Spinous & Transverse processes of vertebrae

• Action: Extension of vertebral column

Erector Spinae

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• Origin: Iliolumbar ligament and iliac crest

• Insertion: Lower border of 12th rib, transverse process of upper lumbar vertebrae

• Action: Depresses rib cage inferiorly and laterally flexes trunk

Quadratus Lumborum

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• Origin: Transverse processes of C3-C6

• Insertion: 1st rib • Action: Elevates 1st

rib, flexes neck forward and laterally, rotates neck

ScalenesAnterior

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• Origin: Transverse processes of C2-C7

• Insertion: 1st rib • Action: Elevates 1st

rib, flexes neck forward and laterally, rotates neck

ScalenesMiddle

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• Origin: Transverse processes of C4-C6

• Insertion: 2nd rib • Action: Elevates 2nd

rib, flexes neck laterally, slightly rotates neck

ScalenesPosterior

MUSCLES OF THE THORACIC WALL

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• Origin: Inferior border of rib above

• Insertion: Superior border of rib below

• Action: Elevates rib cage during inspiration

External Intercostal

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• Origin: Superior border of rib below

• Insertion: Inferior border of rib above

• Action: Depresses rib cage during expiration

Internal Intercostal

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Pectoralis Major

• Origin: Medial half of clavicle, sternum, costal cartilages, aponeurosis of external abdominal oblique

• Insertion: Intertubular groove of humerus

• Action: Flexes, adducts, and medially rotates humerus, draws body upward in climbing

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• Origin: Anterior surface of ribs 3 to 5

• Insertion: Coracoid process of scapula

• Action: Draws scapula down and forward and elevates ribs

Pectoralis Minor

MUSCLES OF THE ANTERIOR ABDOMINAL WALL

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• Origin: Pubic symphysis and crest of pubis

• Insertion: Xiphoid process and cartilages of ribs 5 to 7

• Action: Tenses abdominal wall and flexes vertebral column

Rectus Abdominus

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• Origin: External surface of lower 8 ribs

• Insertion: Anterior half of iliac crest and linea alba

• Action: Compresses abdomen, contralaterally rotates and flexes vertebral column

External Abdominal Oblique

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• Origin: Lateral half of inguinal ligament, anterior iliac crest and thoracolumbar fascia

• Insertion: Lower four ribs, linea alba and by conjoined tendon to pubis

• Action: Compresses abdomen, ipsilaterally rotates and flexes vertebral column

Internal Abdominal Oblique

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• Origin: Lateral third of inguinal ligament, anterior iliac crest, and thoracolumbar fascia

• Insertion: Linea alba, and by conjoined tendon to pubis

• Action: Compresses abdomen

Transverse Abdominis

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The End