Why would cause cervical spondylosis headache?

Many of the elderly often appear after occipital pain, Moreover, with the increase of age, pain more frequently, after doctors for a medical examination, the majority of cervical disease diagnosed. Why cervical disease can also cause headaches?
Current clinical view, the headache of cervical disease caused mainly have the following five reasons:
(L) of the cervical spine disease involving neck muscles, neck caused lasting spastic muscle contraction, leading to muscle blood flow cycle obstacles can be free of lactic acid, 5 - serotonin, such as bradykinin skin disease caused material headache.
(2) cervical spondylosis direct stimulation, traction head oppression or sensitive organizations headache caused headaches.
(3) lesions stimulate, oppression or injury first, second and three pairs of cervical nerve caused headaches, particularly for the re-occipital, but also through the medulla oblongata nuclear trigeminal nerve or the spinal cord reflex role due to pain radiotherapy to the head.
(4) lesions can stimulate or promote the oppression of the sympathetic nerve plexus veins around the neck or other sympathetic to vertebral - basilar artery system or intracranial artery systolic and diastolic obstacles arising from headaches. 　　 (5) Promote vein type of cervical disease, due to lesions involving promote vein directly to vertebral - basilar artery system insufficiency caused headaches.