8.3 Ribs, Sternum & Soft-Tissue Neck
Key Takeaways
- Rib series combine AP/PA projections with obliques that place the affected axillary ribs parallel to the IR; above-diaphragm ribs use inspiration, below-diaphragm ribs use expiration and higher exposure factors.
- Sternum is typically demonstrated with a shallow RAO (or LPO) to project the sternum over the heart, plus a true lateral; breathing technique or short exposure may blur lung markings depending on protocol.
- Soft-tissue neck (lateral and sometimes AP) evaluates airway, foreign body, croup/epiglottitis patterns, and retropharyngeal soft tissues—technique prioritizes soft-tissue contrast, not bony detail alone.
- For suspected epiglottitis, minimize distress, keep the child upright when possible, and obtain a true lateral with gentle positioning; airway emergencies override routine throughput.
- Breathing instructions are part of positioning: inspiration for upper ribs and chest, expiration for lower ribs, suspended respiration for lateral sternum, and quiet breathing or phonation options only when protocol specifies.
8.3 Ribs, Sternum & Soft-Tissue Neck
Quick Answer: Image ribs with frontal + oblique projections that elongate the axillary portion of the side of interest; use inspiration above the diaphragm and expiration below. Demonstrate the sternum with shallow RAO (sternum over heart) and lateral. Use soft-tissue neck technique for airway/foreign-body questions—true lateral, soft-tissue exposure, and calm airway-aware positioning.
Ribs, sternum, and soft-tissue neck sit at the intersection of skeletal and respiratory imaging. On the CAMRT exam, these procedures test whether you can choose the correct oblique, match breathing phase to diaphragm level, and adapt technique when the clinical question is bone versus airway soft tissue.
Rib Radiography
Clinical goals
- Localize fractures, lytic/blastic lesions, or postoperative change
- Separate axillary ribs from superimposed structures
- Relate rib findings to underlying lung (often a PA chest is included in the series or ordered separately)
Many departments obtain a PA (or AP) chest as part of a “rib series” because pneumothorax and lung injury may accompany trauma—even when the order says “ribs.” Follow the order and protocol; if trauma mechanism is high and chest views are omitted, clarify with the care team when policy expects them.
Above-diaphragm vs below-diaphragm ribs
| Region | Ribs of interest | Breathing | Exposure / Bucky notes |
|---|---|---|---|
| Above diaphragm | Typically 1–8/9 posterior and corresponding axillary arcs | Full inspiration (diaphragm down) | Chest-like technique; upright preferred |
| Below diaphragm | Lower ribs (≈8–12) | Expiration (diaphragm up, abdomen denser but ribs elevated into field) | Higher exposure; often abdomen technique range; recumbent common |
Why expiration for lower ribs? Elevating the diaphragm places upper abdominal density differently and can improve visualization of lower ribs through the upper abdomen depending on protocol—know your department chart. The exam concept is: match breathing phase to whether the ribs of interest are thoracic or thoracoabdominal.
Obliquity principles
Axillary ribs are foreshortened on straight AP/PA. Rotate the patient so the affected side’s axillary ribs are parallel to the IR (elongated).
Teaching patterns commonly used:
| Side / region of interest | Common oblique approach (verify with protocol) |
|---|---|
| Right posterior / axillary ribs | RPO (or complementary anterior oblique systems) to elongate right axillary ribs |
| Left posterior / axillary ribs | LPO for left axillary elongation |
| Anterior rib pain | Some protocols prefer PA and anterior obliques (RAO/LAO) so the area of interest is closer to the IR |
Memory aid used in many programs: For posterior rib pain, use posterior oblique positions (RPO/LPO) that place the affected side against/near the IR and elongate that axillary margin; for anterior pain, anterior obliques (RAO/LAO) may be preferred. Always confirm with the local protocol book—naming systems (which oblique shows which ribs) must match how your facility teaches, but the physics idea is constant: rotate to reduce superimposition and place the side of interest parallel to the IR.
Typical rotation is on the order of 45° for general rib obliques (some sites use 30–45°). Mark the side of interest clearly.
Positioning summary — ribs
| Projection | Patient position | CR | Criteria |
|---|---|---|---|
| PA/AP ribs (above) | Upright preferred; back or chest to IR per protocol | ⊥ to mid-IR at level of interest | Side of interest included; inspiration; markers |
| AP ribs (below) | Recumbent or upright; expiration | ⊥ lower rib region | Lower ribs through upper abdomen density |
| Oblique ribs | 30–45° RPO/LPO or RAO/LAO per side & protocol | ⊥ centered to side of interest | Axillary ribs elongated; spine rotated away from area of interest |
| Chest (if included) | Standard PA | T7, 180 cm | Lung fields for concurrent thoracic injury |
Trauma adaptations
- Do not roll a patient with unstable spine or multiple injuries solely for “pretty” rib obliques—use cross-table adaptations, limited angles, or CT per care pathway.
- Support the injured side; minimize pain-induced motion.
- Horizontal beam may be needed for recumbent patients.
Sternum Radiography
The sternum is thin and overlie the thoracic spine on a straight AP/PA. The classic solution is a shallow oblique that shifts the sternum off the spine and over the heart shadow, plus a lateral.
RAO sternum (common teaching default)
| Element | Typical practice |
|---|---|
| Position | RAO approximately 15–20° (right anterior shoulder against IR) — projects sternum over heart |
| Alternative | LPO can produce a similar relationship in some protocols |
| SID | Often 75–100 cm range per protocol (some use 30 in / 76 cm to magnify sternum slightly—know local chart) |
| CR | Perpendicular to mid-sternum (jugular notch to xiphoid midpoint) |
| Breathing | Orthostatic breathing technique (shallow breaths during long exposure) to blur lung markings or suspended respiration with short exposure—protocol dependent |
| Collimation | Tight to sternum |
Why RAO over the heart? The heart provides a more homogeneous density backdrop than the spine, improving sternum visibility.
Lateral sternum
| Element | Typical practice |
|---|---|
| Position | True lateral, upright preferred; arms back or as protocol; sternum centered |
| SID | ≈ 100–180 cm per protocol |
| CR | Perpendicular to mid-sternum |
| Breathing | Suspended inspiration (chest expanded, sternum elevated) |
| Criteria | Sternum in profile without rotation (ribs superimposed posteriorly as for lateral chest cues); manubrium to xiphoid included |
Positioning summary — sternum
| Projection | Patient position | CR | Criteria |
|---|---|---|---|
| RAO sternum | 15–20° RAO | ⊥ mid-sternum | Sternum over heart, free of spine; optional breathing blur of lungs |
| Lateral sternum | True lateral upright | ⊥ mid-sternum | Sternum in profile; full length; no rotation |
Trauma note: If the patient cannot oblique, limited laterals, horizontal-beam laterals, or CT may replace classic RAO. Do not force rotation against spinal precautions.
Soft-Tissue Neck
Soft-tissue neck radiography evaluates the upper airway and cervical soft tissues more than detailed cervical vertebrae (though bony landmarks remain useful). Indications include:
- Suspected foreign body (coin, food bolus)
- Croup vs epiglottitis pattern evaluation (especially pediatrics)
- Retropharyngeal swelling / abscess concern
- Airway narrowing, masses, or post-extubation assessment per protocol
Lateral soft-tissue neck
| Element | Typical practice |
|---|---|
| Position | Upright preferred; true lateral; chin slightly elevated; shoulders depressed |
| CR | Perpendicular to mid-neck (often near laryngeal prominence / C4 region depending on protocol) |
| Collimation | Nasopharynx / oropharynx through upper trachea as ordered; include soft-tissue outline |
| Exposure | Soft-tissue technique (lower contrast emphasis for air column and prevertebral soft tissues—not a high-detail bone cervical spine exposure) |
| Breathing / phonation | Quiet breathing through nose; some foreign-body protocols use phonation (“eee”)—follow order |
| Criteria | Airway column visible; mandible rami superimposed (no rotation); soft tissues not cut off |
AP soft-tissue neck
Used less often than lateral but may show bilateral airway symmetry, foreign body laterality, or complement lateral findings. CR through mid-neck; exposure soft-tissue optimized; chin elevated to reduce mandibular superimposition.
Epiglottitis and airway emergency considerations
Suspected epiglottitis is an airway emergency. Practice principles:
- Keep the patient calm and upright when possible; do not force recumbency.
- Avoid distressing the child with multiple repositions or throat inspection in the imaging room—imaging supports clinical diagnosis; it does not replace emergency airway readiness.
- A single high-quality true lateral soft-tissue neck is often the radiograph of choice when imaging is pursued.
- Have suction/oxygen/emergency support available per facility pathway; prioritize patient condition over “complete series.”
Classic teaching appearance (for recognition, not for over-calling): enlarged epiglottis (“thumbprint”) with variable aryepiglottic swelling. Croup more often shows subglottic narrowing (“steeple” sign) on AP. Exam items may contrast these patterns and the positioning needed to show them.
Foreign body
- Include the full region suggested by history (neck ± chest).
- Lateral neck for upper airway objects; chest PA/lateral for distal migration.
- Radiolucent objects may require clinical correlation; radiography rules in opaque objects and secondary signs.
Breathing Instructions — Integrated Cheat Sheet
| Examination | Typical breathing instruction |
|---|---|
| PA/AP/lateral chest | Full inspiration, suspend |
| Expiration chest (special) | Full expiration, suspend |
| Ribs above diaphragm | Inspiration, suspend |
| Ribs below diaphragm | Expiration, suspend |
| RAO sternum | Shallow breathing during exposure or suspend per protocol |
| Lateral sternum | Inspiration, suspend |
| Soft-tissue neck | Quiet breathing; special phonation only if ordered |
| Decubitus chest | Inspiration if patient able |
Clear instructions reduce motion and wrong-phase exposures—both are common causes of repeats and dose waste (ALARA link to RTR.1).
Image Critique Links to RTR.6
Ask on every rib/sternum/neck image:
- Is the side of interest elongated and free of avoidable superimposition?
- Was breathing phase correct for the anatomy?
- Is rotation present that mimics pathology (asymmetric airway, pseudo-thick prevertebral soft tissue)?
- Is technique appropriate for soft tissue vs bone intent?
- Are markers and annotations (upright, side down, inspiration/expiration) correct?
Bottom Line for Ribs, Sternum & Soft-Tissue Neck
For ribs, think side of interest + diaphragm level + correct oblique. For sternum, think shallow RAO over heart + true lateral. For soft-tissue neck, think airway-first: upright calm positioning, soft-tissue exposure, true lateral, and emergency awareness when epiglottitis or critical foreign body is in play. Breathing instructions are not afterthoughts—they are positioning tools that determine whether anatomy is visible on the first exposure.
For radiographic evaluation of the lower ribs below the diaphragm, which breathing instruction is most appropriate?
Why is a shallow RAO commonly used for the frontal sternum projection?
When imaging a child with suspected epiglottitis, which approach is most appropriate?
What is the primary geometric goal of an oblique rib projection for axillary rib pain?