MSA2 Pectoral Girdle Muscles

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MSA2 Pectoral Girdle Muscles
2011-04-22 16:49:38
Soma MSA2 muscles pectoral girdle

MSA2 LP 7 & 8
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  1. Trapezius
    • Origin- EOP, medial portion of the superior nuchal line, ligamentum nuchae, SPs of C7 - T12
    • Insertion- Lateral portion of clavicle, acromion, spine of scapula (same as origins of deltoid)
    • 3 separate muscle bellies
    • Upper bilateral- extends head and neck
    • Upper unilateral- laterally flexes, rotates head and neck to contralateral side, upwardly rotates scapula, elevates scapula
    • Middle trap- Adducts scap, stabilizes scap
    • Lower trap- Depresses scap, upwardly rotates
    • NR, S
  2. Rhomboids
    • Origins: Major- SPs of T2-T5; Minor- SPs of T1 and C7
    • Insertion: medial border of the scapula between the spine and inferior border
    • Actions: adduction of the scap (primary), elevation and downward rotation of the scap
    • NR; deep to trapezius
  3. Levator Scapula
    • Origin: TVPs of C1 - C4
    • Insertion: Medial border of the scapula, between the superior angle and above the spine of the scap
    • Actions: Unilaterally- Elevates scap (primary), downwardly rotates, laterally flexes the head and neck, rotates head to same side (ipsilaterally); bilaterally- extends head and neck
    • NR; Both- deep at origin and insertion
  4. Serratus Anterior
    • Origin- External surfaces of upper 8 or 9 ribs
    • Insertion- Anterior (costal) surface of medial border of the scapula
    • (accessible from lateral scap)
    • Actions- Abducts scapula, depresses scapula, upwardly rotates scapula, holds medial border of scap against ribcage, may act in forced inspiration
    • NR; both- deep to anterior scap
  5. Pectoralis Minor
    • Origin- ribs 3, 4 and 5
    • Insertion- Coracoid process of scap
    • Actions- Depresses scap, abducts scap, downwardly rotates scap, assists in forced inspiration
    • NR; deep