The biceps
Biceps brachii · musculus biceps brachii
The two-headed muscle at the front of your upper arm that bends the elbow and turns the palm up.
What it does
The biceps runs from two points on the shoulder blade to the radius just below the elbow. It bends your elbow, but its strongest job is twisting the forearm to turn the palm upwards, the movement you use to drive in a screw or open a jar.
Surprising fact
The biceps is a stronger supinator (palm-turner) than it is an elbow bender. Most elbow bending is done by the brachialis underneath it.
Why it matters
Lifting something heavy with a sudden jerk can tear the biceps tendon at the elbow or shoulder, leaving a "Popeye" bulge in the arm. Bending your knees and lifting smoothly protects it.
Nearby
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Sources
Drafted with AI help; awaiting a human fact-check against these sources.
Open in the 3D atlas · Suggest a correction · Not medical advice.
3D models: Z-Anatomy & BodyParts3D (CC BY-SA 4.0 / 2.1 JP). Card text CC BY 4.0.