Normal functional activity of the cervical spine is thirty-five to forty-five degrees of forward flexion, thirty-five to forty-five degrees of posterior extension, forty-five degrees each of lateral flexion and sixty to eighty degrees each of left and right rotation. Clinical significance: If the cervical spine is restricted in forward flexion, it is generally a lesion in the upper segment of the cervical spine. Restriction of posterior extension is generally a lesion of the lower cervical spine. Restriction of lateral flexion is usually a lesion in the middle segment of the cervical spine. Restriction of left and right movement is usually a lesion of the atlantoaxial joint. You can check your cervical spine based on these simple movements.