(From bis, and caput ). A double headed muscle.

Biceps humeri, called also biceps internus humeri: Dr. Hunter calls it bice/is flexor. It rises by two heads; one of them, which is a slender tendon, from the uppermost part of the glenoid cavity; it runs across, within the cavity of the joint, under the ligament of the articulation, passes in the groove between the two tubercles, and, going down, grows fleshy. The second head rises from the extremity of the coracoid process, runs down the axilla, and joins the first, forming a tendon, which sinks between the interstices of the muscles, to be inserted into the tubercle on the inside of the radius. This muscle, besides being a flexor, acts as a rotator of the radius, when the hand is prone. This muscle sends off an aponeurosis towards the inside of the arm, which is the part wounded when the tendon is said to be pricked by bleeding. This aponeurosis was first noticed by Cowper.

Biceps extensor. This muscle rises by two heads; the longer, taking its origin from near the neck of the os humeri, runs between the teres major and minor, down the back part of the arm, and joins the short head which rises on the outside of the deltoid, and is inserted into the olecranum.

Biceps femoris. This muscle hath two heads; the longer rises in one mass with the semitendinosus, but, having advanced a little way, they part: they arise from the protuberance of the ischium on its back part; as the biceps advances it becomes fleshy. Between the biceps and the semitendinosus, the vessels lie in the ham. The short head rises from the lineal aspera, between the insertion of the biceps and the origin of the vastus extemus. The two heads join, and are inserted into the superior epiphysis, or outer part of the fibula.

It bends the tibia, and partly rotates the leg by turning the foot outwards. Cowper.