A 44-year-old female presents to clinic with complaints of neck pain that has been ongoing for a couple months. She says that she has started a new job and spends most of her day seated behind a desk. She has tried over the counter medications without relief. Vitals are within normal limits. Osteopathic structural examination reveals that her C1 vertebrae is restricted in translation to the left. The restriction seems to improve with extension. Given the physical exam findings, which of the following is the most likely diagnosis?