Deltoid

Muscle Origin

Spine of scapula, a

Deltoid

Deltoid

cromion and lateral 1/3 of clavicle to deltoid tuberosity of humerus.

Anterior Part: Anterior border of the lateral third of the clavicle Medial Part: Lateral border of the acromion process of the scapula.
Posterior Part: Inferior edge of the scapular spine.

Insertion

Deltoid tuberosity of humerus.

From this extensive origin the fibers converge toward their insertion on the deltoid tuberosity on the middle of the lateral aspect of the shaft of the humerus; the middle fibers passing vertically, the anterior obliquely backward and laterally, and the posterior obliquely forward and laterally. Though traditionally described as a single insertion, the deltoid insertion is divided into two or three discernible areas corresponding to the muscle’s three areas of origin. The insertion is an arch-like structure with strong anterior and posterior fascial connections flanking an intervening tissue bridge. Wiki

Action

Abduct arm at shoulder.

Shoulder abduction, flexion and extension. When all its fibers contract simultaneously, the deltoid is the prime mover of arm abduction along the frontal plane. The arm must be medially rotated for the deltoid to have maximum effect.

Innervation – Nerve control

Axillary nerve.

The deltoid is innervated by the axillary nerve.[17] The axillary nerve originates from the anterior rami of the cervical nerves C5 and C6, via the superior trunk, posterior division of the superior trunk, and the posterior cord of the brachial plexus.

The axillary nerve is sometimes damaged during operations on the axilla, such as for breast cancer. It may also be injured by anterior dislocation of the head of the humerus. Wiki

Artery

Thoracoacromial artery, anterior and posterior humeral circumflex artery.

Antagonist muscles

Latissimus dorsi.

Pectoralis major and minor, Subclavius, Serratus anterior, Trapezius, Latissimus dorsi, Rhomboid major and minor, and Levator scapulae. Wiki

Pictures of muscles

 

Trigger Point Referrals

 

Stretching description

 

Exercises

 

Injuries

 

Treatment

 

Additional Resources
Sports Lab
Wiki

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