A cervical X‑ray with flexion and extension are lateral neck X‑rays taken while you bend the head forward (flexion) and backward (extension). They evaluate alignment, motion and potential instability of the cervical spine after trauma, in suspected ligament injury, or when assessing fusion and degenerative disease. The test is quick, usually done standing or sitting, and involves low radiation exposure.

Three standard cervical spine X‑ray views are: lateral, anteroposterior (AP), and open‑mouth odontoid (APOM). The lateral view assesses vertebral alignment, intervertebral disc spaces, prevertebral soft tissues, and C7–T1. The AP view evaluates vertebral bodies and frontal alignment. The open‑mouth odontoid view visualizes C1–C2 and the odontoid process for fractures or dislocation.

Flexion–extension of the cervical spine are sagittal‑plane movements: flexion bends the head/neck forward (looking down) and extension bends it backward (looking up). Goniometric norms are roughly 45° flexion and 45° extension. Movement occurs mainly at the occipito‑atlantal, atlanto‑axial and lower cervical segments and is produced by neck flexors (longus colli, SCM) and extensors (splenius, semispinalis).

The purpose of lateral cervical spine radiographs in flexion and extension is to assess cervical stability and segmental mobility by demonstrating vertebral alignment, intervertebral translation, and focal angulation. These views help detect ligamentous injury, occult subluxation or instability after trauma or surgery, and evaluate fusion or degenerative motion. They complement neutral radiographs when dynamic instability is suspected.

Flexion and extension views of the spine are dynamic X-ray images taken with the patient bending forward (flexion) and backward (extension). They assess spinal segment movement, detect instability or abnormal motion (e.g., spondylolisthesis), and evaluate ligamentous injury or fusion success. Commonly used for cervical and lumbar spine after trauma, persistent pain, or when standard films are inconclusive.

Measure cervical flexion and extension with a goniometer or inclinometer while the patient sits upright with the thorax stabilized. Align the device axis at the external auditory meatus (or C7), stationary arm vertical and moving arm along the nose/forehead. For flexion, tuck the chin and bend forward; for extension, tilt the head back and look up. Normal active range ≈ 40–50°. Repeat and average three trials.