If a patient cannot tilt his neck back, it is due to the presence of the following etiologies: 1. The patient may have developed a cervical spine related injury, such as developing a cervical spine spine fracture or having a misalignment of the small joints of the cervical spine. The patient’s cervical spine may have severe pain and restricted movement, and the patient may not be able to complete the movement due to pain or bony obstruction when trying to do backward tilting. 2, may be caused by spasm of the neck muscles, such as the patient’s poor posture or cold neck, which may lead to spasm of the neck muscles, and the patient will have obvious restricted movement when doing activities such as backward tilting or head turning. 3. It is common for patients to have neurological related pathologies, such as Green-Barre syndrome, which may lead to muscle paralysis, and then unable to complete the movement.