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Spine and Pelvis

Cervical Spine

Anatomy

Students should be able to identify the following structures on radiographic images:

body, vertebral arch, vertebral foramen, vertebral canal, intervertebral disks, transverse processes, spinous process, laminae, pedicle, superior articular process, inferior articular process, zygapophyseal joints (a.k.a.. apophyseal jts. or interarticular facet joints), atlas, axis, dens (odontoid), vertebra prominens, transverse foramina, articular pillar

Routine Projections (ARRT Required)

AP Axial Cervical Spine

CR Location & Positioning

  • SID: 40 inches (102 cm) or department standard
  • Patient position: Supine or upright AP with shoulders level; midsagittal plane centered
  • Adjustments: Elevate/protrude chin so occlusal plane is roughly perpendicular to IR; avoid mandibular overlap of mid-cervicals
  • CR: 15–20° cephalad to C4 (at or just below thyroid cartilage), centered midline
  • Pt. Instructions: Suspend breathing; don’t swallow
  • Exposure: Short exposure time; grid/DR per protocol

Evaluation Criteria

  • Coverage: C3 through at least T2 visible with surrounding soft tissues included
  • Rotation checks: Spinous processes midline; SC joints equidistant to spine; mandibular angles symmetric
  • Motion checks: Sharp cortical margins and trabeculae; airway edges distinct
  • Technique checks: Open intervertebral disk spaces from cephalic angle; adequate penetration through shoulders; no saturation
  • Clinical aim: Survey vertebral bodies, disk spaces, hardware, or cervical ribs as applicable

AP Open-Mouth (Odontoid)

CR Location & Positioning

  • SID: 30–40 inches per department protocol
  • Patient position: Supine or upright; mouth wide open
  • Adjustments: Align lower margin of upper incisors with mastoid tips so occlusal plane is perpendicular to IR; slight head tilt as needed
  • CR: Perpendicular through open mouth to midline at C1–C2
  • Pt. Instructions: Keep mouth open; softly say “ah” to depress tongue; suspend breathing
  • Exposure: Short exposure; tight collimation

Evaluation Criteria

  • Coverage: Dens, C1 lateral masses, and C2 body included; atlantoaxial joints visible
  • Rotation checks: Mandibular rami equidistant from dens; lateral masses symmetric
  • Motion checks: No motion of jaw or tongue; crisp dentition and dens margins
  • Technique checks: Tongue not over C1–C2; no incisors or skull base superimposing dens
  • Clinical aim: Assess dens integrity and C1–C2 alignment

Lateral Cervical Spine (Grandy)

CR Location & Positioning

  • SID: 60–72 inches
  • Patient position: True lateral, seated or standing, shoulder against detector
  • Adjustments: Depress shoulders (equal weights if safe); elevate chin slightly or protrude mandible to clear C1–C2; MSP vertical
  • CR: Horizontal, perpendicular to C4; top of IR about 1 inch above EAM
  • Pt. Instructions: Suspend on full expiration to lower shoulders; hold still
  • Exposure: Short time; grid or high kVp per protocol

Evaluation Criteria

  • Coverage: C1 through at least C7 and ideally T1; prevertebral soft tissues included
  • Rotation checks: Zygapophyseal joints superimposed; articular pillars aligned; mandibular rami nearly superimposed
  • Motion checks: Sharp endplates and spinous tips; no swallow blur
  • Technique checks: Open disk spaces; adequate penetration through shoulders; visible soft tissue detail
  • Clinical aim: Evaluate alignment, disk height, facet relationships, and prevertebral swelling

Cervicothoracic Lateral (Swimmer’s)

CR Location & Positioning

  • SID: 60–72 inches
  • Patient position: Lateral (upright preferred or recumbent)
  • Adjustments: Raise arm closest to IR overhead; depress opposite shoulder; MSP parallel; head neutral lateral
  • CR: Perpendicular to C7–T1 (2 inches above jugular notch); 3–5° caudal if shoulder can’t depress
  • Pt. Instructions: Suspend breathing; minimize motion
  • Exposure: Consider breathing technique only if immobilized; use compensating filter if available

Evaluation Criteria

  • Coverage: C5–T3 region with C7–T1 clearly demonstrated
  • Rotation checks: Humeral heads offset (one anterior, one posterior) with minimal superimposition on spine
  • Motion checks: Sharp vertebral margins despite shoulder thickness
  • Technique checks: Sufficient penetration to see vertebrae between shoulders; good soft tissue detail
  • Clinical aim: Visualize C7/T1 when standard lateral is inadequate

Posterior Oblique Cervical Spine (RPO/LPO) – AP Axial Obliques

CR Location & Positioning

  • SID: 60–72 inches
  • Patient position: Upright preferred; posterior oblique 45° with shoulder against IR
  • Adjustments: Keep head aligned at same 45° as torso; elevate/protrude chin to clear upper spine without rotating superior vertebrae
  • CR: 15–20° cephalad to C4; center to spine
  • Pt. Instructions: Suspend breathing; hold still
  • Exposure: Short exposure; tight collimation

Evaluation Criteria

  • Coverage: C2–C7 intervertebral foramina and pedicles
  • Rotation checks: Foramina “side up” open and uniform; pedicles of elevated side in profile
  • Motion checks: Crisp foraminal walls; no swallow blur
  • Technique checks: Open disk spaces; occiput and mandible not obscuring C1–C2
  • Clinical aim: Demonstrate intervertebral foramina on the elevated side

Anterior Oblique Cervical Spine (RAO/LAO) – PA Axial Obliques

CR Location & Positioning

  • SID: 60–72 inches
  • Patient position: Upright preferred; anterior oblique 45°
  • Adjustments: Chin elevated/protruded to clear upper spine; align head with torso (avoid extra head turn)
  • CR: 15–20° caudad to C4; center to spine
  • Pt. Instructions: Suspend breathing
  • Exposure: Short exposure; tight collimation

Evaluation Criteria

  • Coverage: C2–C7 intervertebral foramina and pedicles
  • Rotation checks: Foramina “side down” open and uniform; pedicles of dependent side in profile
  • Motion checks: Sharp foraminal margins
  • Technique checks: Open disk spaces; no mandibular or occipital superimposition on C1–C2
  • Clinical aim: Demonstrate intervertebral foramina on the dependent side

Supplemental Projections

Lateral Flexion and Extension Cervical Spine

CR Location & Positioning

  • SID: 60–72 inches
  • Patient position: True lateral upright
  • Adjustments: Flexion—tuck chin toward chest; Extension—elevate chin and look slightly up; keep shoulders depressed and in same plane
  • CR: Horizontal to C4
  • Pt. Instructions: Suspend breathing; move only head/neck as directed
  • Exposure: Short time; obtain only after stability is cleared per protocol

Evaluation Criteria

  • Coverage: C1–C7 included on both positions
  • Rotation checks: Articular pillars aligned; true lateral maintained in both views
  • Motion checks: Clear spinous processes; no swallow blur
  • Technique checks: Distinct disk spaces; interspinous spacing widens in flexion and narrows in extension
  • Clinical aim: Assess cervical stability and motion limits.

AP Dens (Fuchs)

CR Location & Positioning

  • SID: 40 inches
  • Patient position: Supine (non-trauma only)
  • Adjustments: Elevate chin so line from tip of chin to mastoid tips is vertical; MSP perpendicular
  • CR: Perpendicular just distal to chin, centered midline to level of mastoid tips
  • Pt. Instructions: Suspend breathing; hold still
  • Exposure: Short exposure; tight collimation

Evaluation Criteria

  • Coverage: Entire dens within foramen magnum
  • Rotation checks: Mandible and cranium symmetric about dens
  • Motion checks: Sharp dens margins
  • Technique checks: Adequate contrast to see cortical outline within foramen
  • Clinical aim: Alternative dens visualization when open-mouth view is inadequate

Hows & Whys of Cervical Spine Radiography

Anatomy

  • Which unique features distinguish typical cervical vertebrae from other regions?
    Transverse foramina for vertebral vessels and bifid spinous tips, with prominent articular pillars.
  • What motion occurs primarily at the atlanto-occipital and atlanto-axial joints?
    Atlanto-occipital flexion/extension (“yes”) and atlanto-axial rotation around the dens (“no”).
  • Why is C7 called vertebra prominens?
    Its long nearly horizontal spinous process is easily palpable posteriorly.

Positioning 

  • Why use a 15–20° cephalic angle on the AP axial?
    To align the beam with inferiorly tilted cervical disk spaces so they open on the image.
  • Why elevate or protrude the chin on AP axial and lateral views?
    To keep the mandible from obscuring C1–C2 and the upper cervical bodies.
  • Why use 60–72 inch SID for lateral and obliques?
    To decrease magnification from OID and better include C7.
  • Why depress the shoulders on the lateral?
    To reveal C7/T1 without additional beam angulation.
  • Why rotate 45° and angle the CR 15–20° on obliques?
    Because cervical foramina open 45° to the MSP and tilt about 15° inferiorly.
  • Why align the occlusal plane and keep the mouth open for the odontoid?
    To clear the dens of teeth and skull base while dropping the tongue inferiorly.
  • Why choose the Fuchs method when the open-mouth fails?
    Hyperextension projects the dens within the foramen magnum, bypassing dental/skull-base overlap.
  • Why raise the near arm and depress the far shoulder for Swimmer’s?
    To separate humeral heads and clear the C7–T1 junction.

Technique & Image Evaluation

  • How can you tell the cephalic angle was correct on AP axial?
    Intervertebral disk spaces are open and spinous processes stay midline.
  • How can you tell chin position was correct on AP axial?
    Mandible and occiput overlay only C1–C2, not mid-cervicals.
  • How can you tell the lateral is truly lateral?
    Zygapophyseal joints and articular pillars are superimposed and mandibular rami nearly overlap.
  • How can you tell you included C7/T1?
    C7 and the C7–T1 interspace are visible; otherwise a Swimmer’s is needed.
  • How can you tell obliques are correctly rotated and angled?
    Target-side foramina are uniformly open from C2/3 to C7/T1 with the corresponding pedicles in profile.
  • How can you tell the odontoid view is aligned?
    Dens and lateral masses are symmetric; no teeth or skull base over the dens; no tongue shadow on C1–C2.
  • How can you tell Fuchs succeeded?
    The dens lies entirely within the foramen magnum with symmetric margins.
  • How can you tell functional laterals are adequate?
    All seven vertebrae are included; spinous processes separate in flexion and approximate in extension without rotation change.

Clinical Applications

  • What projection is obtained first in acute trauma?
    Cross-table lateral to assess alignment and prevertebral soft tissues before additional views.
  • When pick posterior versus anterior obliques?
    Posterior obliques show “side up” foramina; anterior obliques show “side down” and may reduce thyroid dose due to PA orientation.
  • When is Swimmer’s required?
    When C7/T1 is not visible on the standard lateral due to shoulder superimposition.
  • If you want me to convert any sections into a mobile-optimized quick chart (same Pressbooks-friendly lines), I can add that at the end.

 

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Radiographic Procedures Review Guide Copyright © 2025 by Carla M. Allen and Taylor M. Otto is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, except where otherwise noted.

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