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The name of the two fleshy masses which occupy the posterior and superficial part of the leg, Gemelli; (F.) Gastrocnemiens, Jumeaux de la jambe, Bifemoro-calcanicns- (Ch. ;) the two constituting the Gastrocnemius externus, of English anatomists. These muscles are distinguished into internal and external, which are distinct above, but united at their inferior extremity. They are long, flat, and thick; and arise-the former from the posterior part of the outer condyle of the femur; the latter, from the pasterior part of the inner condyle of the same bone. The aponeurosis, which unites these muscles below, joins with that of the solaris, and forms with it, a large tendon, which, under the name Tendo Achillis, is inserted at the posterior part of the calcaneum. These muscles extend the foot on the leg, and the leg on the foot. They can, also, bend the leg and the thigh reciprocally on each other. For the Gastrocnemius internus, see Soleus.