Muscle | Proximal attachment | Distal attachment | Innervation* | Main action |
Superficial posterior axio-appendicular (extrinsic shoulder) muscles | ||||
Trapezius | Medial third of superior nuchal line; external occipital protuberance; nuchal ligament; spinous processes of C7 - T12 vertebrae | Lateral third of clavicle; acromion and spine of scapula | Spinal accessory nerve (CN XI) (motor fibers) and C3, C4 spinal nerves (pain and proprioceptive fibers) | Descending part elevates; ascending part depresses; and middle part (or all parts together) retracts scapula; descending and ascending parts act together to rotate glenoid cavity superiorly |
Latissimus dorsi | Spinous processes of inferior 6 thoracic vertebrae, thoracolumbar fascia, iliac crest, and inferior 3 or 4 ribs | Floor of intertubercular sulcus of humerus | Thoracodorsal nerve (C6, C7, C8) | Extends, adducts, and medially rotates humerus; raises body toward arms during climbing |
Deep posterior axio-appendicular (extrinsic shoulder) muscles | ||||
Levator scapulae | Posterior tubercles of transverse processes of C1 - C4 vertebrae | Medial border of scapula superior to root of scapular spine | Dorsal scapular (C4, C5) and cervical (C3, C4) nerves | Elevates scapula and rotates its glenoid cavity inferiorly by rotating scapula |
Rhomboid minor and major | Minor: nuchal ligament; spinous processes of C7 and T1 vertebrae Major: spinous processes of T2 - T5 vertebrae | Minor: smooth triangular area at medial end of scapular spine Major: medial border of scapula from level of spine to inferior angle | Dorsal scapular nerve (C4, C5) | Retract scapula and rotate its glenoid cavity inferiorly; fix scapula to thoracic wall |
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