The goal of this clinical trial is to measure the effects of osteopathic manipulative treatment (OMT) on tissues of the craniocervico-mandibular unit (CCMU) in individuals with neck pain and headaches.

The main questions to answer are:

1. How does OMT affect CCMU muscle stiffness
2. How does OMT affect jaw motion
3. How does OMT affect autonomic function
4. Is pain pressure threshold affected by OMT of the CCMU

Participants will undergo the following interventions:

1. Photos taken to measure head and neck angles
2. Ultrasound
3. Smooth Pursuit Neck Torsion Test
4. Motion Capture
5. Autonomic Protocol
6. Algometry
7. Surveys

Myofascial pain is a major health problem that results in a decrease in life quality and functioning, and it imposes a burden on healthcare systems. Muscles and joints of the cervical spine contain numerous sensory receptors that are important for the integration of head and neck movements with temporomandibular joint and eye movements. In humans, jaw and neck movements are integrated, possessing a high degree of spatiotemporal consistency. This is necessary to maintain natural jaw function. Because of neural and myofascial connections, dysfunction in one region can cause dysfunction and pain in a neighboring region. Jaw and cervical spine dysfunction have been linked previously. Orofacial pain and temporomandibular joint dysfunction are both associated with increased stiffness of the masticatory muscles and neck disability and muscle tenderness. Also, abnormal craniocervical posture that manifests as forward head malposition with hyperextension of the upper cervical is commonly associated with dysfunction of the CCMU. Considering head and neck postures can influence muscle stiffness and activity, it is plausible that positional changes in the neck, such as poor posture, are part of a larger somatic dysfunction sequela that reflects biomechanical alterations of the CCMU that can eventually lead to chronic pain and dysfunction in eye and jaw motion. In addition to myofascial dysfunction, the role of the autonomic nervous system (ANS) in chronic pain has been documented and is related to dysfunctional pain that continues in the absence of noxious stimuli. Previous studies have demonstrated a correlation between neck pain and temporomandibular dysfunction and pain, impaired eye movements, visual disturbances, and autonomic dysfunction.

Manual therapies have been shown to restore myofascial and autonomic balance. OMT directed at the cervical region can restore balance to both the CCMU and the autonomic nervous system, which can improve function and decrease pain. Treatment of the deep neck muscles, including the suboccipital muscles, is effective at improving neck pain, disability and range of motion. Also, this can manifest as an improvement in jaw and eye motion, and a restoration of balance within the autonomic nervous system. Further research is needed to better understand the role of CCMU dysfunction in chronic pain conditions of the head and neck and to provide a mechanistic understanding of OMT in the treatment of CCMU dysfunction.

The primary objective is to measure the effects of OMT on tissues of the CCMU in individuals with neck pain and headaches. Specifically, investigators will measure the following as part of this objective:

• Stiffness changes in the masseter, trapezius, sternocleidomastoid, and semispinalis capitis and cervicis.
• Eye tracking changes measured by a smooth pursuit neck torsion test (SPNT).
• Changes in jaw morphometrics during motion using a 9 -marker setup and capturing motion using VICON.
• Changes in autonomic function (heartrate variability, skin conductance, pupillary response) using a battery of tests including divided attention test, Valsalva maneuver, cold pressor test, and deep breathing.
• Pain pressure threshold measured by algometry.

A secondary objective is to demonstrate a relationship between the clinical presentation of CCMU dysfunction and self-reported complaints of stress, anxiety, pain, and disability and how OMT affects these self-reported measures. To achieve this secondary objective, the investigators will use the following:

• Self-reported visual disturbances measured by survey.
• Depression, Anxiety, and Stress measured by Depression, Anxiety, Stress Scale (DASS-21).
• Average neck pain, headaches, and temporomandibular joint pain duration, intensity and frequency measured by survey.
• Functional ability measured by the neck disability index (NDI).
• Headaches measured by the Headache impact test (HIT-6).

This research aims to answer possible mechanisms of OMT intervention in CCMU dysfunction that presents clinically as neck pain, headache, dizziness, and visual disturbances. In addition, the investigators aim to demonstrate a relationship between self-reported measures of pain and disability and dysfunction while demonstrating improvements in these measures because of OMT treatment.

Inclusion Criteria:

• male and female subjects 19-65 years old
• neck pain and/or headaches of > 1 month duration

Exclusion Criteria:

• prior cervical or thoracic spinal surgery
• diagnosis cervical radiculopathy or pinched nerve in the neck
• diagnosis of jaw disease or dysfunction
• diagnosis of connective tissue or muscle disorders
• diagnosis of cancer
• previous spinal cord injury
• Inflammatory arthritis and fibromyalgia
• eye movement disorder
• known pregnancy (hormonal changes affecting tissues could be a confounding variable)
• tobacco use
• known diabetes or prediabetes
• allergy to ultrasound gel (propylene glycol)
• history of manual therapy treatment within the past 2 weeks
• history of injection for pain within the past month
• currently taking muscle relaxers