biceps

biceps , any muscle having two heads, or fixed ends of attachment, notably the biceps brachii at the front of the upper arm and the biceps femoris in the thigh. Originating in the shoulder area, the heads of the biceps merge partway down the arm to form a rounded mass of tissue linked by a tendon to the radius, the smaller of the two forearm bones. When the biceps contracts, the tendon is pulled toward the heads, thus bending the arm at the elbow. For this reason the biceps is called a flexor. It works in coordination with the triceps brachii, an extensor. The biceps also controls rotation of the forearm to a palm-up position, as in turning a doorknob. The size and solidity of the contracted biceps are a traditional measure of physical strength.

biceps muscle with double head or attachment. XVII. — L. biceps two-headed, f. BI- + -ceps, rel. to caput HEAD.

biceps (by-seps) n. a muscle with two heads. b. brachii a muscle that extends from the shoulder to the elbow and is responsible for flexing the arm and forearm. b. femoris a muscle at the back of the thigh, responsible for flexing the knee.