Temporomandibular Joint (TMJ) Disorder: This condition is characterized by pain and dysfunction of the jaw joint and surrounding muscles. It is a common cause of neck pain referred from the jaw due to the close anatomical relationship between the TMJ and the cervical spine.

Tension Headache: Often involves the neck and can refer pain to the jaw area due to the involvement of the suboccipital and cervical muscles.
Cervical Spondylosis: Degenerative changes in the cervical spine can cause neck pain that may radiate to the jaw, especially if there is compression or irritation of the cervical nerves.
Myofascial Pain Syndrome: This condition involves pain and inflammation of the muscles and their surrounding connective tissue, which can occur in the neck and jaw muscles, leading to referred pain.

Acute Coronary Syndrome (ACS): Although less common, jaw pain can be a referred symptom of myocardial infarction (heart attack), especially in women. It is crucial to consider ACS in the differential diagnosis due to its high mortality rate if untreated.
Giant Cell Arteritis: This condition can cause jaw claudication (pain in the jaw when chewing) and is associated with polymyalgia rheumatica. It's a medical emergency due to the risk of blindness if not promptly treated.
Cervical Vertebral Artery Dissection: A tear in the wall of one of the arteries in the neck can lead to a stroke. Jaw and neck pain can be initial symptoms, making prompt diagnosis critical.

Eagle Syndrome: Characterized by an elongated styloid process or calcified stylohyoid ligament, which can cause sharp, stabbing pain in the jaw and neck.
Neoplastic Processes: Tumors of the jaw, cervical spine, or surrounding tissues can cause pain in the jaw and neck, though these are less common causes.
Infectious Processes: Abscesses or infections in the dental, jaw, or cervical spine areas can cause severe pain and require urgent medical attention.