Procedures · ARRT Radiography
Bony Thorax
The RAO sternum and its breathing technique, true vs false vs floating ribs, the rib decision table, and above or below diaphragm breathing rules for the ARRT Radiography exam.
Overview
Bony Thorax covers the sternum, the sternoclavicular joints and all 12 pairs of ribs, and the work is in the decisions about position and breathing. The sternum is about 7 inches long in three divisions (manubrium, body, xiphoid process) and sits directly in front of the thoracic spine, so a straight PA barely shows it. The fix is a 15 to 20 degree RAO, which slides the sternum left of the spine onto the uniform heart shadow, paired with an orthostatic breathing technique: low mA and a 3 to 4 second exposure so shallow breathing blurs the lungs while the bone stays sharp.
Anterior landmarks map to vertebral levels: jugular notch at T2-T3, with the sternoclavicular joints either side of it at the same level, sternal angle at T4-T5, xiphoid tip at T9-T10. Rib classification: ribs 1 to 7 are true, 8 to 12 are false, and 11 and 12 are floating. Every rib forms a costovertebral joint, but only ribs 1 to 10 form costotransverse joints.
The rib routine follows one rule: place the area of interest closest to the receptor and rotate the spine away from it. Posterior ribs get an AP plus a posterior oblique, anterior ribs get a PA plus the opposite anterior oblique, and both rib obliques use 45 degrees. Breathing splits at the diaphragm: expose upper ribs erect on inspiration so ribs 1 through 9 clear the dome, and lower ribs supine on expiration so ribs 10 through 12 show below it.
SC joint obliques use only 10 to 15 degrees and demonstrate the downside joint. Flail chest (adjacent ribs broken in two or more places) is imaged erect when tolerated, and a common rib trauma routine adds a PA and lateral chest to rule out pneumothorax. Procedures carries 66 of the 200 scored questions to 28 February 2027, and 72 from 1 March 2027.
What you’ll learn in this chapter
The 18 study slides and 11 quiz questions in this chapter break down as follows. 3 chapters are free in full with a free account. The others come with a paid plan, and paid plans open soon.
Bony Thorax
- Bony Thorax: Ribs, Sternum & SC Joints
Anatomy
- The Sternum
- Landmarks and Their Vertebral Levels
- Ribs: True, False and Floating
- Anatomy of a Typical Rib
- Quiz
- Joints of the Bony Thorax
Technique
- Sternum Technique, and Why RAO
Sternum
- RAO Sternum
- Quiz
- Lateral Sternum
SC joints
- Sternoclavicular Joints
- Quiz
Ribs
- Above or Below the Diaphragm
- Quiz
- The Rib Decision Table
- Quiz
- AP and PA Rib Projections
- Axillary Ribs
Clinical indications
- Clinical Indications
Image critique
- Critiquing a Bony Thorax Film
- Quiz
Summary
- Every Projection in One Place
Recap
- What to Carry Out of This Chapter
- Quiz
- Quiz
- Quiz
- Quiz
- Quiz
Key terms in this chapter
These are 8 key terms from this chapter. Use them as a flashcard pre-quiz.
- RAO Sternum
- The routine sternum oblique at 15 to 20 degrees, shifting the sternum just left of the spine onto the homogeneous heart shadow. A deep barrel chest needs about 15 degrees, a thin chest about 20.
- Orthostatic (Breathing) Technique
- Low mA with an exposure of at least 3 seconds while the patient breathes shallowly. Lung markings blur over the sternum while the bony margins stay sharp; not used on young pediatric patients.
- True, False and Floating Ribs
- Ribs 1 to 7 reach the sternum by their own costocartilage (true); ribs 8 to 12 do not (false); ribs 11 and 12 also float, with no costocartilage or anterior attachment at all.
- Costovertebral vs Costotransverse
- The rib head meets a vertebral body on all 12 ribs (costovertebral). The rib tubercle meets a transverse process only on ribs 1 to 10 (costotransverse), so ribs 11 and 12 lack that joint.
- Rib Positioning Rule
- Put the area of interest nearest the image receptor and turn the spine away from it. Right posterior ribs take an AP plus RPO; left anterior ribs take a PA plus RAO.
- Above vs Below the Diaphragm
- Upper ribs are exposed erect on inspiration so ribs 1 to 9 clear the dome; lower ribs are exposed supine on expiration to show ribs 10 to 12 as a minimum.
- Sternal Angle
- The palpable ridge where the manubrium meets the sternal body, at the T4-T5 level. The second costal cartilage joins the sternum here.
- Flail Chest
- Fracture of adjacent ribs in two or more places from blunt trauma, threatening chest wall instability and underlying pulmonary injury. Imaged erect if the patient's condition permits.
Sample practice question: Thorax and Abdomen
One free sample question from the Thorax and Abdomen subcategory, like those in its 285-question bank. Several chapters share each sample, so it may not match this chapter's topic. See the format, the rationale style, and the difficulty before you sign up.
On a properly positioned and exposed PA chest radiograph in an adult, how many posterior ribs should be visible above the diaphragm to indicate adequate inspiration?
Show answer and rationale
A, Incorrect: 8 posterior ribs falls short of the count.
B, Correct: Correct. At least 10 posterior ribs above the diaphragm indicates adequate inspiration. Bontrager also notes that patients with pulmonary disease or trauma may be unable to reach 10.
C, Incorrect: Bontrager's count uses posterior ribs, not anterior ribs.
D, Incorrect: Costophrenic angle visibility is part of quality assessment but does not specifically indicate inspiration adequacy.
Hands-on
Practice the positioning
Open the Positioning Lab to drill body position, central ray, anatomy, and common errors for each projection in this chapter.
- Ribs Posterior AP AP posterior ribs, erect above the diaphragm, supine below. SID 40". Breathing varies by location.
- Ribs Anterior PA PA anterior ribs, erect. SID 40". Full inspiration.
- Ribs AP Oblique AP oblique ribs, 45-degree. SID 40". Breathing varies by location.
- Ribs PA Oblique PA oblique ribs, 45-degree. SID 40". Breathing varies by location.
- Sternum PA Oblique RAO PA oblique sternum (RAO), 15-20 degrees. SID 40". Breathing technique.
- Sternum Lateral Lateral sternum, erect. SID 60-72". Shoulders and arms drawn back.
- Sternoclavicular Joints PA PA sternoclavicular joints. SID 40".
- Sternoclavicular Joints PA Oblique PA oblique SC joints, 10-15 degrees. SID 40".
Read 3 chapters free.
The free tier unlocks 3 complete chapters, 50 practice questions, and 1 sample timed exam. No credit card required.
Frequently asked questions
What does the Bony Thorax chapter cover?
Bony Thorax covers the sternum, the sternoclavicular joints and all 12 pairs of ribs, and the work is in the decisions about position and breathing. The sternum is about 7 inches long in three divisions (manubrium, body, xiphoid process) and sits directly in front of the thoracic spine, so a straight PA barely shows it. The fix is a 15 to 20 degree RAO, which slides the sternum left of the spine onto the uniform heart shadow, paired with an orthostatic breathing technique: low mA and a 3 to 4 second exposure so shallow breathing blurs the lungs while the bone stays sharp.
How many study slides are in the Bony Thorax chapter?
This chapter has 18 study slides and 11 quiz questions across 10 sections. The full chapter comes with a paid plan, and paid plans open soon. The free tier includes 3 complete chapters.
Is this chapter aligned with the current ARRT Content Specifications?
Every chapter on this site is mapped to the ARRT Radiography Content Specifications, but our line-by-line check against ARRT's outline isn't finished, so keep ARRT's outline beside it. Nothing here follows your exam date, so check which version applies to you. This chapter falls under the Procedures domain of the official ARRT exam blueprint.