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Extrensic Int. Back
Traps, Lats, Levator Scapula, Rhom major & minor / Serratus posterior sup & inf
Muscle | Origin | Insertion | Nerve | Action |
---|---|---|---|---|
Rhomboid major | PA: SP of T2-T5 | medial border of the scapula from the spine to the inferior angle | Dorsal scapular nerve (C 4-5) | Retract scapula and rotate the scapula in downward direction to depress the glenoid cavity, fix scapula to the thorax; can assist with elevation of scapula with L. S |
Rhomboid minor | PA: nuchal ligament & SP of C7 + T1 | medial border of the scapula from the spine to the inferior angle | Dorsal scapular nerve (C 4-5) | Retract scapula and rotate the scapula in downward direction to depress the glenoid cavity, fix scapula to the thorax; can assist with elevation of scapula with L. S |
Serratus posterior superior | SA: Ligamentum nuchae, SP of C7-T3 | IA: Superior borders of ribs 2-4 | 2nd - 5th intercostal nerves | Elevate ribs |
Serratus posterior inferior | SA: SP of T11-L2 | IA: Inferior borders of ribs 8-12 near angles | Ventral rami of 9th - 12th thoracis spinal nerves | Depress ribs |
Trapezius | SA: medial 1/3 of superior nuchal line, external occipital protuberance, ligamentum nuchae, SP of C7-T12 | IA: lateral 1/3 of clavicle, acromion, spine of scapula | Spinal Accessory Nerve (CN XI) | Upper fibers: elevate scapulaMiddle fibers: retract scapulaLower fibers: depress scapula |
Latissimus dorsi | PA: SP of inferior 6 thoracic vertebrae, thoracolumbar fascia, iliac crest, inferior 3-4 ribs | DA: floor of intertubercular groove of the humerus | Thoracodorsal nerve (C6-8) | Extends, adducts, and medially rotates the humerus |
Levator scapula | PA: Posterior tubercles of transverse processes of C1-C4 | DA: Superior aspect of the medial border of the scapula | Dorsal scapular nerve (C5) & cervical (C3, C4) nerves | Elevates scapula and tilts the glenoid cavity inferiorly by rotating the scapula in downward direction |