Lab 5: Gross Anatomy of Muscular System: Head, Neck, & Torso

epicranius: frontal belly

origin: epicranial aponeurosis

insertion: skin of eyebrows and root of nose

action: with aponeurosis fixed, frontal belly raises eyebrows

epicranius: occipital belly

origin: occipital and temporal bones

insertion: epicranial aponeurosis

action: fixes aponeurosis and pulls scalp inferiorly

orbicularis oculi

origin: frontal and maxillary bones and ligaments around orbit

insertion: tissue of eyelid

action: closes eye, produces blinking, squinting, draws eyebrows inferiorly

zygomaticus major & minor

origin: zygomatic bone

insertion: skin and muscle at corner of mouth

action: raises lateral corners of mouth upward (smile)

orbicularis oris

origin: arises indirectly from maxilla & mandible; fibers blend w/fibers of other muscles associated with lips

insertion: encircles mouth; inserts into muscle and skin at angles of mouth

action: closes lips, purses and protrudes lips (kiss & whistle muscle)

buccinator

origin: molar region of maxilla and mandible

insertion: orbicularis oris

action: compresses cheek (as in whistling), draws corner of mouth laterally, holds food between teeth during chewing

masseter

origin: zygomatic arch and maxilla

insertion: angle and ramus of mandible

action: prime mover of jaw closure, elevates mandible

temporalis

origin: temporal fossa

insertion: coronoid process of mandible

action: closes jaw, elevates and retracts mandible

platysma

origin: fascia of chest (over pectoral muscles) and deltoid

insertion: lower margin of mandible, skin, and muscle at corner of mouth

action: tenses skin of neck, depresses mandible, pulls lower lip back and down

sternohyoid

origin: manubrium and medial end of clavicle

insertion: lower margin of hyoid bone

action: depresses larynx and hyoid bone when acting with sternothyroid and omohyoid; may also flex skull if mandible is fixed

sternocleidomastoid

origin: manubrium of sternum and medial portion of clavicle

insertion: mastoid process of temporal bone and superior nuchal line of occipital bone

action: Both contracting simultaneously: flexion of neck

When acting independently: rotate head toward shoulder on opposite side

pectoralis major

origin: clavicle, sternum, cartilage of ribs 1-6 (or 7), and aponeurosis of external oblique muscle

insertion: fibers converge to insert by short tendon into intertubercular sulcus of humerus

action: prime mover of arm flexion, adducts, medially rotates arm; with arm fixed, pulls chest upward

serratus anterior

origin: lateral aspect of ribs 1-8 (or 9)

insertion: vertebral border of anterior surface of scapula

action: prime mover to protract and hold scapula against chest wall; rotates scapula, essential to raising arm, fixes scapula for arm and abduction

pectoralis minor

origin: anterior surface of ribs 3-5, near their costal cartilages

insertion: coracoid process of scapula

action: with ribs fixed, draws scapula forward and inferiorly; with scapula fixed, draws rib cage superiorly

external intercostals

origin: inferior border of rib above (there are 11 pairs between ribs)

insertion: superior border of rib below

action: pull ribs toward one another to elevate rib cage; aid in inspiration

internal intercostals

origin: superior border of rib below (there are 11 pair between ribs)

insertion: inferior border of rib below

action: draw ribs together to depress rib cage; aid in forced expiration, antagonistic to external intercostals

diaphragm

origin: inferior border of rib and sternum, costal cartilages of last 6 ribs and lumbar vertebrae

insertion: central tendon

action: prime mover of inspiration flattens on contraction; increasing vertical dimensions of thorax; increases intrabdominal pressure

rectus abdominis

origin: pubic crest and symphysis

insertion: xiphoid process and costal cartilages of ribs 5-7

action: flexes and rotates vertebral column; increases abdominal pressure, fixes and depresses ribs, stabilizes pelvis during walking, used in sit-ups and curls

external oblique

origin: anterior surface of lower 8 ribs

insertion: linea alba, pubic crest and tubercles, iliac crest

action: flexes and rotates vertebral column; increases abdominal pressure, fixes and depresses ribs, stabilizes pelvis during walking, used in sit-ups and curls + compresses abdominal wall, aids muscles of back in trunk rotation and lateral flexion, used in oblique curls

internal oblique

origin: lumbar fascia, iliac crest, and inguinal ligament

insertion: linea alba, pubic crest, costal cartilages of last 3 ribs

action: flexes and rotates vertebral column; increases abdominal pressure, fixes and depresses ribs, stabilizes pelvis during walking, used in sit-ups and curls + compresses abdominal wall, aids muscles of back in trunk rotation and lateral flexion, used in oblique curls

transverse abdominis

origin: inguinal ligament, iliac crest, cartilages of last 5-6 ribs, lumbar fascia

insertion: linea alba and pubic crest

action: compresses abdominal contents

trapezius

origin: occipital bone, ligamentum nuchae, spines of C7 and all thoracic vertebrae

insertion: acromion and spinous process of scapula, lateral third of clavicle

action: raises, rotates, and retracts (adducts) scapula and stabilizes it, extends head, superior fibers elevate scapula (shrug shoulders), inferior fibers depress scapula

latissimus dorsi

origin: indirect attachment to spinous processes of lower 6 thoracic vertebrae, lumbar vertebrae, last 3-4 ribs, iliac crest

insertion: floor of intertubercular sulcus of humerus

action: prime mover of arm extension, adducts and medially rotates arm, bring arm down in power stroke (as in striking a blow)

levator scapulae

origin: Transverse processes of C1 - C4

insertion: Medial border of scapula superior to spine

action: Elevates and adducts scapula; with fixed scapula, laterally flexes neck to the same side

quadratus lumborum

origin: iliac crest and lumbar fascia

insertion: Inferior border of rib 12; transverse processes of lumbar vertebrae

action: each flexes vertebral column laterally; together extend the lumbar spine and fix rib 12; maintains upright posture

iliocostalis

origin: most lateral of the erectorspinae muscles. Iliac crest, transverse processes of lumbar, thoracic, and cervical vertebrae, and/or ribs 3-6 depending on specific part

insertion: ribs and transverse processes of vertebrae about six segments above origin; longissimus also inserts onto mastoid process.

action: extend and bend the vertebral column laterally; fibers of the longissimus also extend and rotate head

longissimus

origin: between iliocostalis and spinalis. Iliac crest, transverse processes of lumbar, thoracic, and cervical vertebrae, and/or ribs 3-6 depending on specific part

insertion: ribs and transverse processes of vertebrae about six segments above origin

action: extend and bend the vertebral column laterally; fibers of the longissimus also extend and rotate head

spinalis

origin: most medial of erectorspinae muscles. Iliac crest, transverse processes of lumbar, thoracic, and cervical vertebrae, and/or ribs 3-6 depending on specific part

insertion: ribs and transverse processes of vertebrae about six segments above origin

action: extend and bend the vertebral column laterally; fibers of the longissimus also extend and rotate head

rhomboid major

origin: spinous process of C7 and T1-T5;

beneath trapezius and inferior to levator scapulae

insertion: medial border of scapula

action: stabilize scapulae, pull scapulae medially (retraction), rotate glenoid cavity downward

rhomboid minor

origin: superior;

spinous process of C7 and T1-T5; beneath trapezius and inferior to levator scapulae

insertion: medial border of scapula

action: stabilize scapulae, pull scapulae medially (retraction), rotate glenoid cavity downward