Aponeurosis

Aponeurosis (from Greek apo- meaning from and neuron meaning tendon or nerve), a term that originally designated a portion of a muscle located where the muscle fibers transition into tendons. At present, A. usually refers to a broad or moderately broad connective tissue plate consisting of strong white fibers arranged mostly parallel to each other; by means of this plate, broad muscles attach to the skeleton or to other body tissues. Sometimes the term A. is used to denote a very dense fascia. Therefore, many authors call the palmar and plantar fascia the palmar and plantar A., based on the fact that the dense middle portion of these fasciae represents a degenerated muscular portion of a special superficial flexor of the fingers, which on the forelimb originated from the medial condyle of the humerus, and on the hindlimb from the lateral condyle of the femur. In the armadillo (Armadillo), this muscle consists of muscle fibers throughout its entire length. In humans, muscle fibers have been preserved only in the upper portion of this muscle. For the arm, this would be the m. palmaris, and for the leg, the m. plantaris.