Here's why:

* Movement: Muscles attach to bones, and when they contract, they pull on the bones, causing movement.

* Support: The skeleton provides a framework for the muscles to attach to and allows for leverage during movement.

* Protection: Muscles protect the delicate organs and tissues within the body, which are often situated near bones.

While the muscular system works closely with the skeletal system, it also interacts with other systems like the nervous system (for control and coordination), the circulatory system (for oxygen and nutrient delivery), and the endocrine system (for hormone regulation).