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Triceps brachii
The triceps brachiiExtensor Back of upper arm; straightens the elbow muscle is a three-headed muscle, as the name “triceps” suggests.

Photography, text, and labels by Rob Swatski, Assistant Professor of Biology, Harrisburg Area Community College – York Campus, York, PA.
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
Triceps brachii Origin
Long Head: The long headRounded proximal end that fits into the acetabulum of the hip bone. of the triceps originates from the infraglenoid tubercle of the scapulaTriangular “shoulder blade” on posterior thorax; connects clavicle and humerus..
Lateral Head: The lateralAway from the midline of the body. head originates from the posterior surface of the humerusLong bone of the upper arm; articulates with scapula at shoulder and radius/ulna at elbow., above the radial groove.
Medial Head: The medialToward the midline of the body head originates from the posterior surface of the humerus, below the radial groove.
Triceps brachii Insertion
The triceps brachii muscles merge into a single tendon. This tendon inserts into the olecranon processLarge, curved posterior projection—forms the bony point of the elbow. of the ulnaMedial forearm bone (pinky side); forms the elbow hinge with humerus.. It forms the posterior border of the elbow joint.
Triceps brachii Actions
Elbow Extension
Stabilization of the Elbow Joint
Assistance in Shoulder Extension
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
- triceps brachii
- head
- scapula
- lateral
- humerus
- medial
- olecranon process
- ulna