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Trapezius
Origin: Medial superior nuchal line and external protuberance of the occipital line, ligamentum nuchae and spinous processes on C7- T12.
Insertion: Lateral clavicle, acromion and spine of scapula.
Actions:
Upper fibres: Elevate and upwardly rotate scapula.
Mid fibres: Retract scapula.
Lower Fibres: Depress scapula.
Innervation: C3, C4 and accessory cranial nerve (XI).
Daily uses: Shrugging shoulders.
Other muscles …

Supraspinatus
Origin: Supraspinous fossa
Insertion: Greater tuberosity of the humerus
Actions: Abduction Stabilisation of the humerus
Innervation: Suprascapular nerve
Daily uses: Holding shopping bags away from the body

Teres Minor
Origin: Mid section of the lateral border of the scapula
Insertion: Greater tuberosity on the humerus
Actions:External rotation, Shoulder adduction
Innervation: Axillary nerve
Daily uses: Brushing hair
Subscapularis
Origin: Anterior (costal) surface of the scapula
Insertion: Lesser tuberosity of the humerus
Actions: Internal rotation , Adduction
Innervation: Upper and lower subscapular nerves
Daily uses: Tucking the back of your shirt into your trousers
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