Cilia and flagella are extensions that arise from the cell membrane. Flagella are longer than cilia. Both structures are responsible for cell motility. The microscopic features of these two structures are also very similar. The central core is known as axoneme. These show nine pairs of microtubules that are arranged peripherally and one pair of microtubule is also seen in the centre. This is $9+2$ arrangement. The central tubules are connected to some peripheral tubules by means of a sheath.