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Deltoid
When you walk, the deltoidAbductor / Flexor / Extensor Caps shoulder; lifts arm and moves it in multiple directions. helps you swing your arms. Next time you walk try not to swing your arms. It hurts mentally.

Photography, text, and labels by Rob Swatski, Assistant Professor of Biology, Harrisburg Area Community College – York Campus, York, PA.

Deltoid Origin
Anterior (Clavicular) Part: This portion of the deltoid originates from the lateralAway from the midline of the body. third of the clavicleS-shaped collarbone; connects sternum to scapula; helps brace the shoulder..
Middle (Acromial) Part: The middle portion originates from the acromion, a bony projection on the scapulaTriangular “shoulder blade” on posterior thorax; connects clavicle and humerus. (shoulder blade).
Posterior (Spinal) Part: The posterior part of the deltoid originates from the spineProminent ridge on the posterior scapula dividing it into supraspinous and infraspinous fossae. of the scapula.
Deltoid Insertion
The deltoid muscle converges from these three points. It inserts into the deltoid tuberosity on the lateral aspect of the humerusLong bone of the upper arm; articulates with scapula at shoulder and radius/ulna at elbow.. The humerus is the long bone of the upper arm. This insertion allows the deltoid to exert force on the arm, enabling a wide range of shoulder movements.
Deltoid Actions
Extension and Lateral Rotation of the Arm
Flexion and Medial Rotation of the Arm
Abduction of the Arm
Interactive Materials
Use this 3D Viewer to Explore the Muscles of the Upper Body
“Open3DModel – Upper limb – English labels” by Open3D project, Jan Kooloos, RadboudUMC, Eungyeol Lee, LUMC et al, license: CC BY-SA
Identify More Muscles
Link to more Muscle Identification
Upper Arm Muscles
Forearm Muscles
Calf Muscles
Anterior Thigh Muscles
Posterior Thigh Muscles
Knee Structures
Chest Muscles
Back Muscles
Abdominal Muscles
Neck Muscles
Head Muscles
List of terms
- deltoid
- anatomy
- lateral
- clavicle
- scapula
- spine
- humerus