1. Anatomy, Pathology, and Radiography
Bony Thorax
Anatomy, Pathology, and Radiography
All images copyright Mosby Inc., an affiliate of Elsevier Inc.

2. Bony Thorax Anatomy Thoracic Vertebrae Sternum Ribs
The bony thorax, otherwise known as the ribcage, protects the heart and lungs. The bony thorax is more than just the ribs. Ribs alone do not make a complete cage. They need attachments to keep them together. Therefore, the bony thorax is formed by three segments: the sternum (breast bone), 12 pairs of ribs, and 12 thoracic vertebrae.

3. Anatomy
Sternum
The narrow, flat bone that is about 6” long in the center of your chest is called the breast bone or sternum. CPR directions indicate to vigorously rub the sternum with your knuckles. If the patient doesn’t wake up, begin CPR. Chest compressions are performed on the sternum because most of the heart is directly under it.
The sternum consists of 3 parts: the manubrium, body, and xiphoid process. The manubrium is the superior aspect of the sternum. You can find it by finding the jugular notch. The jugular notch is the top of the manubrium. If you follow your fingers down from the jugular notch, you will feel the swell of the manubrium. It ends at the sternal angle where the manubrium meets the sternal body.
Did you know that the collarbones sit on the sternum? The medial ends come to rest on the manubrium. There are two facets named after them: clavicular notches. The SC joint is where the sternum meets the clavicle.
The xiphoid process is the distal end of the sternum. For CPR, your hands should be at least 2” above the xiphoid tip so you don’t break it off. At the extreme ends, this 6” bone has two prominent bony landmarks for radiographers. The jugular notch aligns with the interspace between T2 and T3. The xiphoid process sits over T10 (10th thoracic vertebra).

4. Ribs Anatomy True ribs False ribs Floating ribs
There are 24 ribs, usually referred to as 12 pairs of ribs. Do you ever get confused between the true, false, and floating ribs? Did you know that all floating ribs are false ribs, but not all false ribs are floating? The first 7 pairs of ribs are called the true ribs because they attach to the sternum. Even though you think of the ribs attaching directly to the sternum, there is actually a cartilage connection between the two. This is important when looking at articulations (joints).
The rest of the ribs, pairs 8-12, are false because they don’t attach directly to the sternum. Run your hands along the bottom of your ribs. Follow them from your waist area up to the xiphoid process. Notice how they angle up? Pairs 8, 9, and 10 have longer cartilage that angle up to the cartilage between the 7th rib and the sternum.
Ribs 11 and 12 are called floating because they only have one attachment in the back (at the vertebrae). In front, they “float” with no attachments. Remember that every rule has an exception. Some people have extra vertebrae and some people have extra ribs.
Take a close look at a typical rib. The short part goes in back. The “heads” of the ribs attach to the vertebrae. The tubercle is there to articulate with the transverse processes of the vertebrae.
False ribs
Floating ribs

5. Anatomy
Joints
Joints are also called articulations. The most freely movable joints are synovial. That means they are surrounded by a capsule with a bit of fluid inside. The least movable (a.k.a. immovable) are the fibrous joints. In between these is the cartilaginous or synchondroses type of joint that is connected with hyaline cartilage or fibrocartilage. It might surprise you to learn that not all synovial joints are as large or movable as a knee. Some are quite small and you hardly notice their movement.
The bony thorax has eight different types of articulations. Look at the term costovertebral. Cost means rib. Vertebral refers to vertebrae. O is a combiner that joins the two words. We have cost (rib) to vertebrae – so all 12 ribs have these joints. They are synovial (have a capsule with a little fluid inside), gliding, and freely movable.
You already know that cost is ribs and o joins the two parts of the word. Chondral means cartilage. So costochondral means ribs to cartilage. The first 10 ribs have cartilage at their ends, so these joints are cartilaginous. This makes sense because cartilage is cartilaginous, synchondroses and immovable.

6. Breathing Anatomy Hypersthenic = Less movement Asthenic
The diaphragm is the sheet of muscle under your lungs that moves air in and out. The position of the diaphragm is affected by body habitus. It is higher in hypersthenic patients and lower in asthenic patients. The diaphragm moves about 1 ½ inches between deep inspiration and expiration on average people. Heavier (hypersthenic) patients have less movement.
How does breathing affect the rib cage? The ribs are connected to the sternum with cartilage for a reason. The rib heads (attached to the vertebrae) rotate a bit, but the anterior ends need the ability to stretch. As you take a deep breath in, your ribs move forward, up, and out to the sides (anteriorly, superiorly, and laterally.) The opposite happens as you exhale.
Hypersthenic
= Less movement
Asthenic

7. Anatomy
Knowledge Check
Manubrium, body, xiphoid
What are the three components that make up the bony thorax?
Sternum, ribs, thoracic vertebrae
Costotransverse, rib tubercle, costovertebral
True ribs, false ribs, floating ribs
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8. The bony thorax is comprised of the sternum, ribs, and thoracic vertebrae.
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9. Pathology Diseases: Fractures Tumors Osteomyelitis Osteoporosis
The bony thorax is made of bone. Therefore, it is subject to bone diseases like any other bone in the body. Some of the typical pathologies are fractures, tumors (like the malignancy of chondrosarcoma and the malignancy of multiple myeloma), and osteomyelitis. Osteoporosis (which we normally associate with the spine) can occur throughout the bony thorax too.

10. Click on the correct answer.
Pathology
Knowledge Check
Metastases
Which of the following is increased density of a typically soft bone?
Osteomyelitis
Osteopetrosis
Chondroscarcoma
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11. Increased density of a typically soft bone is called osteopetrosis.
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12. General Exposure Technique
Radiography
General Exposure Technique
65 kVp
PA Oblique Sternum
PA SC Joints
PA Oblique SC joints
70 kVp
All other projections of the bony thorax.
The PA oblique sternum, PA SC joints, and PA oblique SC joints require a 65 kVp. All the other projections of the bony thorax require 70 kVp. While most of these projections require a 40” SID, the sternum is unique. The PA oblique sternum gets a 30” SID to blur the posterior ribs and the lateral gets a 72” to reduce magnification due to increased object to image distance (OID).
Distance:
40” SID for most projections
30” SID for PA oblique sternum
72” SID for lateral sternum

13. PA Oblique Sternum Radiography CR enters here
The PA oblique projection is the ESSENTIAL projection for the sternum. It demonstrates the sternum through the heart. Use a short SID of 30” to blur the ribs. The average rotation is degrees. There are two main breathing techniques used for this image. Have the patient take shallow breaths. Or, for a short exposure, exhale and hold (that is, suspend at end of expiration). For trauma patients, obtain this projection with the patient supine, using the LPO position (AP oblique projection).
Any time you address central rays in oblique projections, you have to pay attention to which side you are imaging. In the PA oblique projection (RAO position), the CR enters the elevated side of the posterior thorax at T7 and 1” lateral to the midsagittal plane.

14. Lateral Sternum Radiography
The sternum also requires a lateral projection. Because the sternum is so far from the image receptor, make sure you use a 72” SID to reduce magnification. One of the key elements of this exam is to have the patient lock his hands together behind his back. Take note of the IR placement. Its upper border should be 1 ½ inches above the jugular notch. Have the patient take a deep breath in and hold it.

15. PA Sternoclavicular Articulations
Radiography
PA Sternoclavicular Articulations
CR on left
images right SC joint
CR on right
images left SC joint
The PA projection of the SC joints (sternoclavicular articulations) is usually a bilateral exam that requires the patient rest his head on his chin, adjusted so that the MSP is vertical. Occasionally, only one side needs to be imaged. For a unilateral projection, have the patient turn his head toward the affected side. Breathing should be suspended at the end of expiration. The CR target is T3.
The SC joints often require the PA oblique projection. The unaffected side is raised degrees, placing the affected side close to the IR. *The joint closest to the IR is shown. The CR is perpendicular to the SC joint closest to the IR, entering T2-3 and 1-2” lateral from the MSP. This is a criss-cross exam. If the CR enters the left side (on the back), it will image the right SC joint. If it enters the right side (on the back), it will image the left SC joint.

16. Ribs Radiography To image anterior ribs, position front close to IR.
To image posterior, put the patient’s back to the IR.
Imaging the ribs is done with the side closest to the IR. So, if the anterior ribs are suspected of having a pathology, the patient would be placed in the PA position with the front of his ribs close to the IR. If the posterior ribs are in question, you would want them to be closest to the IR, so stand the patient with the back to the IR. The curved part of the ribs (axillary portion) are usually shown in oblique projections. Lateral images would obscure the view due to superimposition of the opposite ribs. Use the LAO or RPO positions to image the axillary ribs to clear the heart.

17. Rib Positions Note hand positions! Radiography Posterior Ribs
The anterior ribs need to be placed against the IR, so a PA position is used. Place the IR 1 1/2” above the shoulders. Hand position is important in this image. The backs of the hands are on the hips. Palms face outward, rolling the scapulae away from the rib cage. Suspend breathing at full inspiration to depress the diaphragm as much as possible.
When imaging the posterior ribs, pay attention to whether the ribs above or below the diaphragm are needed. The breathing technique will depend on which you are trying to see because you will use the breath to move the diaphragm out of the way. The position of the IR and CR will change dramatically between these images. For ribs above the diaphragm, the IR is 1 ½” above the shoulders, the hands are behind the head with the elbows pulled in close to move the scapulae out of the field of view. Depress the diaphragm with deep inspiration. The lower ribs require the IR to be placed crosswise with the lower edge at the level of the iliac crests. Suspend at full expiration to elevate the diaphragm.
The axillary ribs are imaged with the AP oblique projection – either RPO or LPO about 45 degrees. The affected side goes closest to the IR. Again, the IR is positioned 1 1/2 “ above the shoulders.
Note hand positions!
Axillary Ribs
PA Upper Anterior Ribs

18. Click on the correct answer.
Pathology
Knowledge Check
Inhale and hold
When imaging the posterior ribs below the diaphragm, what breathing instructions should be given?
Exhale and hold
Breath normally
Take a deep breath. Blow it out. Take a second breath and hold.
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19. When imaging the posterior ribs below the diaphragm, tell the patient to exhale and hold.
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