biceps (bī´sĕps), 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 One of the muscles for bending the elbow, and therefore a determinant of strength for lifting — the glass to the lips, or loads a great deal heavier. Being a discrete and visible muscle, especially when well-developed, it is often displayed as the epitomy of body-building. It is so-named because it has two ‘heads’; both are attached to the scapula (shoulder blade) above the shoulder joint. Each ‘head’ swells into the dual belly of the muscle; this gathers below into a short tendon spanning the front of the elbow joint to be attached on the upper end of the radius.

Stuart Judge

bi·ceps / ˈbīˌseps/ • n. (pl. same or -ceps·es / -sepsiz/ ) a muscle having two points of attachment at one end, in particular: ∎  (also bi·ceps bra·chi·i / ˈbrākēˌī; -kēˌē; ˈbrak-/ ) the large muscle in the upper arm that turns the hand to face palm uppermost and flexes the arm and forearm: he clenched his fist and exhibited his bulging biceps. ∎  (also bi·ceps fem·o·ris / ˈfeməris/ ) Anat. the muscle in the back of the thigh that helps to flex the leg.

biceps A muscle that runs along the large bone of the upper arm (humerus) and is connected to the radius at one end and the shoulder bone (scapula) at the other. Contraction of the biceps causes the arm to flex at the elbow joint (see flexor). It works antagonistically with the triceps, which contracts to extend the arm (see antagonism). See also voluntary muscle.

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.

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

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