A tension headache is caused by excessive pulling force of tight muscles in the back of the neck that exert tension on their attachments on the head.
Forward head posture is extremely common, especially as we age. It is part of a larger posture dysfunctional pattern known as upper crossed syndrome.
Greater occipital neuralgia is caused by compression of the greater occipital nerve, usually by a tight upper trapezius or semispinalis capitis muscle.
To perform orthopedic manual therapy to the neck that is accurate and specific, we need to know the attachments and actions of the muscles of the neck.