CONTRACTION is frequently used by anatomical writers, to express the shrinking up of a fibre, or an assemblage of fibres, when extended.
Convulsions and spasms proceed from a preternatural contraction of the fibres of the muscles of the part convulsed. On the contrary, paralytic disorders generally proceed from a too great laxness of the fibres of the part affected; or from the want of that degree of contraction necessary to perform the natural motion or action of the part. In the first, therefore, the animal spirits are supposed to flow, either in too great a quantity, or irregularly; and, in the last, the animal spirits are either denied a free passage into the part affected, or the tension of the fibrillæ is supposed insufficient to promote the circulation.