MUSCLE OF THE DAY: “Deltoid”

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The deltoid is a three-part (anterior, medial, posterior), thick, triangular shoulder muscle that surrounds the glenohumeral joint on all sides, connecting the collarbone, shoulder and shoulder blade to your upper arm. The name, deltoid, comes from the fourth letter of the Greek alphabet, delta, and more specifically the mathematical symbol for “delta”, meaning the change or difference between two values (think the triangle symbol from math or physics class).

Origin(s) (proximal attachment): Clavicular part: lateral third of the clavicle. Acromial part: acromion (upper most process of the scapula, just above the coracoid). Spinal part: spine of the scapula.

Insertion (distal attachment): Deltoid tuberosity of the humerus.

Action(s): Clavicular part: shoulder flexion and internal rotation. Acromial part: shoulder abduction beyond 15 degrees. Spinal part: Shoulder extension and external rotation. Innervation: Axillary nerve (C5, C6, runs through

Common Injuries to the Deltoid:

Here's what our partners at The Prehab Guys have to say about shoulder & deltoid health:

DELTOID RAISE VARIATIONS

Deltoid raises are a staple shoulder exercise#”

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