Fysiqal
Anatomy
Anatomy
Deltoids
Evidence-grounded — sourced from Fysiqal's fitness knowledge graph· 1 min read
deltoidsshouldermuscle-group
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In one line
The three-headed shoulder muscle — anterior, medial, and posterior deltoid — each with distinct actions.
Detail
The deltoid has three heads — anterior, medial (middle), and posterior — shown in three views in the source (Ellison, 1991). Each head performs a different action: the anterior deltoid is involved in pressing movements, the medial deltoid in true abduction, and the posterior deltoid in horizontal abduction and backward extension. In lateral raises, the exercise involves all three heads (with MEO on the medial deltoid).
Key facts
- Three deltoid heads: anterior, medial (middle), posterior.
- Anterior — pressing/flexion; medial — abduction; posterior — horizontal abduction/extension.
Connections
- anterior-deltoid — front head.
- medial-deltoid — middle head; true abduction.
- posterior-deltoid — rear head; horizontal abduction.
- shoulder-joint-rom — shoulder ROM values.
SourceReference manual
p.380p.460
Cited authorities in source: Ellison (1991).
Educational content only — not medical advice. Always consult a qualified professional for individualized guidance, especially around injury, pregnancy, or medical conditions.
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Atlas Connections
Anterior DeltoidClosely related
The front deltoid head; produces forward flexion, horizontal adduction, and internal rotation — primarily a pressing muscle.The 12 Major Muscle Groups
For balanced development and reduced injury risk, strengthen the 12 major muscle groups (plus obliques and adductors/abductors).Medial DeltoidClosely related
The middle deltoid head; the primary muscle of true shoulder abduction (90°), involving all three heads plus the supraspinatus.Posterior DeltoidClosely related
The rear deltoid head; produces horizontal abduction, backward extension, and external rotation — the most under-emphasized deltoid head.Shoulder / Arm Range of Motion
Arm flexion 135°, shoulder adduction 50°, shoulder hyperextension 45°, shoulder abduction 90–180°.