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Deltoid

The deltoid muscle is used in all side lifting movements and any movement of the humerus on the scapula. It is divided into two portions, anterior and posterior, with the fibres having different roles due to their orientation.

Origin

• Outer 1/3 of the clavicle
• Acromion process
• Spine of the scapula

Insertion

• Deltoid tuberosity on the humerus

Actions

• Anterior portion - Shoulder flexion and internal rotation
• Posterior portion - Shoulder extension and external rotation
• All fibres - Shoulder abduction

Innervation

• Axillary nerve

Daily uses

• Lifting

How can I stretch it?

• Posterior shoulder stretch
• Anterior shoulder stretch
• Anterior shoulder stretch II

How can I strengthen it?

• Lateral raise with dumbbells
• Front raise with dumbbells
• Upright row with a resistance band
• Upright row with a barbell
• Shoulder press machine