biceps

(bīˈsĕpsˌ)

1. A muscle with two heads or points of origin.
2. a. The large muscle at the front of the upper arm that flexes the forearm. Also called biceps brachii.
   b. The large muscle at the back of the thigh that flexes the knee joint. Also called biceps femoris.

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biceps

left: biceps relaxed to extend forearm

right: biceps contracted to raise forearm