Muscle knots in the Semispinalis Capitis are typically located just below the base of the skull, running along the upper neck and the back of the head. When these knots are irritated, they can refer pain upward into the head, often causing a deep, aching headache that feels like it’s wrapping around the top of the skull or behind the eyes. It’s a source of tension headaches, especially after long hours of poor posture or stress.