The bone at the back of the head is called the occipital bone, and the hindbrain protrusion is actually a landmark structure on the occipital bone, called the external occipital ridge. Most of the human bones protrude because there are muscles and tendons attached to this position, which can make the limbs and joints move, and the protrusion of the back of the head also has this role, with the occipital muscles and the trapezius muscle attached to it, which can mainly control facial expressions and head movements, and can do the movement of looking upwards. When you do the head lift and head tilt, the tendons of the trapezius muscle attached to the back of the head will be exercised and become stronger and thicker, and the bones of the back of the head will be pulled by the long-term pulling force, resulting in a gradual protrusion on the surface of the skull, whether it looks or touches with your hands, you will feel a protrusion in the back of the head, and this phenomenon is normal.