The internal framework (or ‘scaffolding’) of a cell within the cytoplasm, composed largely of actin filaments and microtubules (see figure below). In eukaryotic cells, actin filaments (or microfilaments) are active in muscle contraction, intermediate filaments hold microfilaments and microtubules in place, and microtubules serve as routes for organelles to move along. In general, the cytoskeleton helps to maintain the shape of the cell, enables the intracellular transport of organelles like mitochondria and vesicles (using structures such as flagella and cilia), and plays a key role in cell division and movement.
