• Origin

Anterior fibers: lateral third of clavicle

Medial fibers: acromion process of scapula

Posterior fibers: spine of scapula

• Insertion

Deltoid tuberosity of humerus

• Agonist(s)

- Supraspinatus

- Infraspinatus

- Teres minor, and

- Subscapularis

• Antagonist(s)

- Pectoralis major

- Latissimus dorsi, and

- Teres major

• Function

Abducts arm at shoulder joint, assists in flexion, extension, and rotation of arm, stabilizes shoulder joint.

TRIGGER POINT(S)

• Location

Trigger points are located throughout the deltoid muscle (Anterior, Lateral, and Posterior).

These points are found within the muscle belly, near the attachments at the clavicle, acromion, and scapula.

• Pain Referral Pattern

Pain generally refers locally around the shoulder and upper arm.

It can cause diffuse pain in the shoulder area, sometimes extending down the outer side of the upper arm to the elbow.

• Potential Causes

• Overuse from repetitive activities involving lifting or overhead motions

• Poor posture, particularly with rounded shoulders

• Trauma or direct impact to the shoulder

• Strain from carrying heavy loads

• Muscle imbalances between the deltoid and surrounding shoulder muscles

• Prevention Tips

• Use proper lifting techniques and avoid overloading the shoulders

• Incorporate regular stretching and strengthening exercises for the deltoid and surrounding muscles

• Maintain good posture and shoulder alignment, especially during activities involving the upper body

• Gradually increase the intensity of workouts to avoid sudden strain

• Ensure balanced strength training to avoid muscle imbalances.