Fill in the Blanks Our locomotor systemOnline version Complete the gaps with the right word. by Alejandro López 1 muscles heart skeleton knee Tendons Joints elastic rigid bones protect We have 206 . They are hard and . They support the body and the heart , lungs and brain . We have 600 ! They are and flexible . Some muscles move automatically , for example , the . are where two or more bones meet . attach muscles to the bones . This allow the to bend . The hip is a joint and so is the .