Here we will talk about the human torso which of course would attach to the arms and legs and would contain the internal organs which are not required for just about any type of humanoid robot.

The backbone is important for various reasons including supporting the entire body and allowing for various types of stretches and movements.

The robot torso would probably in most cases contain the main computer boards while some of the sensors and servos/actuators could be housed nearest the body part involved like the arms and legs and head.

Most toy robots put the power supply in the feet and the voice speakers near the chest or mouth area and the same can hold true for newer humanoid robots.