Cervical spondylosis is a continuous process, but from a pathological point of view, it can be divided into three stages. 1. intervertebral disc degeneration stage The degeneration of the intervertebral disc starts from the age of 20. The root joint instability caused by degeneration of the fibrous ring is the main cause of accelerated degeneration of the nucleus pulposus. Fibrous degeneration, swelling, fracture and fissure formation can be seen; the nucleus pulposus is dehydrated, the elastic modulus is altered, cracks may form internally, and the degenerated nucleus pulposus may protrude posteriorly with the cartilage plate. If the nucleus pulposus crosses the posterior longitudinal ligament, it is called nucleus pulposus prolapse. The nucleus pulposus may compress the spinal cord as well as compress or irritate the nerve roots. From the biomechanical point of view, the main features of this stage are: change in the elastic modulus of the intervertebral disc, increase in intradiscal pressure, intersegmental instability and stress redistribution. 2. Bone spur formation stage The bone spur formation stage is also a continuation of the previous stage. The formation of bone spur itself indicates the change of stress distribution in the vertebral segment caused by the degeneration of the intervertebral disc in which it is located. From the biomechanical point of view, the formation of bone flab and the hypertrophy of the small joints and ligamentum flavum are compensatory reactions. The result is the re-establishment of mechanical equilibrium. This is a defense mechanism of the body. From the pathological point of view, most scholars believe that the bone flab originates from the mechanization, ossification or calcification of the ligament-disc interstitial space hematoma. Bone spurs of longer duration are as firm as ivory. Because cervical 5-6 is at the central point of cervical physiological forward flexion, the disc is under greater stress, so the osteophytes of cervical 5-6 disc are most common, followed by cervical 4-5 and cervical 6-7. 3. Damage stage As mentioned above, simple degeneration does not necessarily produce clinical symptoms and signs, and this is the difference between cervical spondylosis and cervical degeneration. It is only when the changes in the above two pathological stages have an effect on the surrounding tissues and cause corresponding changes that they become clinically significant. Spinal compression on the spinal cord can come from both anterior and posterior sources, or both. Anterior compression is dominated by intervertebral discs and osteophytes. Anterior median compression may directly invade the anterior central or sulcus artery of the spinal cord. Anterior central division or anterolateral compression mainly invades the anterior horn and anterior cord of the spinal cord and presents with symptoms of conus fasciculi on one or both sides. Lateral and posterior lateral compressions come from the ligamentum flavum, small joints, etc., and present mainly with symptoms of sensory deficits. The pathological changes in the spinal cord depend on the intensity and duration of the pressure. Acute compression can cause impaired blood flow, tissue congestion and edema, and after prolonged pressure, vasospasm, fibrous changes, canal wall thickening and even thrombosis. Both gray matter and white matter of the spinal cord atrophy, with more pronounced degeneration, softening and fibrosis of the gray matter, cystic degeneration of the spinal cord, and cavity formation. The compression of the spinal nerve roots mainly originates from the hooked vertebral joint and the bony bulge at the lateral posterior border of the pushing body. Joint instability and lateral-posterior herniation of the disc can also cause irritation and compression of the nerve roots. Early reactive inflammation such as edema and exudation may occur at the root cuff. Continued compression can cause arachnoid adhesions. Arachnoid adhesions make the nerve roots susceptible to strain injury and degeneration or even Wallerian degeneration. Vertebral artery stenosis due to true hyperplasia and compression is rare. Due to the development of MRI and subtraction angiography (DSA) techniques, it is now found that the vertebral artery often twists and even spirals during cervical degeneration. The vertebral artery is stimulated by the movement of the vertebral joints, causing different degrees of spasm, which reduces the intracranial blood supply and produces vertigo or even falls. Loosening and dislocation of the small posterior joints, destruction of articular cartilage and proliferation of synapses, and relaxation and hypertrophy of the joint capsule can all stimulate the peripheral nerve fibers located around the joints and produce neck pain. The posterior wall of the cervical disc is also innervated by nerve endings, and relaxation and degeneration of the annulus fibrosus and posterior longitudinal ligament can cause peripheral nerve irritation resulting in neck pain and discomfort.