This chapter brings a brief discussion on anatomy, movement, biomechanics and instability of the cervical spine. There are 7 vertebrae of the total 33 vertebrae of spinal column in human cervical spine which are divided into upper and lower cervical spine. The upper cervical spine consists of atlas (C1) and axis (C2) with occipitoatlantal (OC-C1) and atlantoaxial (C1-C2) segments. The lower cervical spine consists of C3 to C7 vertebrae. The bony architecture of typical vertebra, atypical vertebra, uncovertebral joints and facet joints have been described in this chapter. The cervical spine and the skull are connected by various ligaments and joints forming distinct and complex articular complexes at the craniovertebral junction (CVJ). Blood is supplied to vertebral column by way of segmental arteries that arise near it from the aorta or from adjacent arteries in areas beyond the extent of the aorta. Muscular action at the cervical spine is dependent on a combination of activities of a great number of muscles and whether or not they contract bilaterally or unilaterally. There are three functional groups i.e. flexors, extensors, and rotators and lateral flexors. Instability is related to the abnormal movement due to trauma, degenerative conditions, tumors or surgery.