25 Transaxial CT Images of the Thorax These images have been windowed to accentuate the water density structures of the heart and great vessels. As a result.

25 Transaxial CT Images of the Thorax

These images have been windowed to accentuate the water density structures of the heart and great vessels. As a result the lungs appearblack, with little detail in them. Only the larger pulmonary vessels appear, as white spots around the hilar areas.

On campus students must draw and identify the anatomy on the line- drawings on the next slide. Students in the degree completion courseshould have an understanding of vascular anatomy that make testing on the drawings unnecessary. But if you need a refresher try these drawings. The ability to visualize these structures is important to the study of cross sectional anatomy of the thorax.

First page number in parenthesis is Netter’s 3rd edition Second page number in parenthesis is Netter’s 4th edition

Introduction to the Thorax

1 Superior & inferior vena cava2 Rt. atrium3 Tricuspid valve4 Rt. ventricle5 Pulmonic valve6 Pulmonary trunk7 Pulmonary arteries8 Pulmonary circulation9 Pulmonary veins10 Left atrium11 Mitral valve12 Left ventricle13 Aortic valve14 Ascending aorta

Can you draw (or visualize) these anatomical structures:An exercise in thoracic cross sectional anatomy recognition

See plate 233 (237)

See plate 234 (238)

See plate 208 (212)

Drawing the heart &pulmonary vessels ismore of a challenge. Ifyou can’t draw it can youvisualize the trip blood makes from the vena cavato the aorta?

In addition to plate 208, thisdrawing from Netter’s Atlas,(dropped from the 3rd edition)is helpful for following pulmonary circulation.

Thorax drawings

1. Superior vena cava 2. Arch of the aorta3. Trachea4. Esophagus5. Body of the Rt scapula6. Spinal cord7. Body of the sternum

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Presentation of Thorax Images

When viewing images from superior to inferior the arteries and veins to the head and upper extremities are numerous, and can be difficult for students to identify. However, beginning at the level of the arch of the aorta, the origin of these vessels (Brachiocephalic, Rt common carotid, Rt subclavian, and the Superior vena cava) are easier to identify as they follow the course studied in a traditional anatomy course.

For this reason the thorax will be studied in two parts: first everything above the heart, then the heart. The first image is 9, and progresses superior to 1. Then back to image 10 and on to 25. Images will be tested in this order.

Image 9

1. Superior vena cava 2. Brachiocephalic artery (233) (237)3. Lt common carotid artery *4. Rt pectoralis major muscle5. Rt pectoralis minor muscle

6. Manubrium of the sternum7. Rt brachiocephalic vein (234) (238)8. Lt brachiocephalic vein **9. Lt costovertebral articulation (joint)10. Rt costotransverse articulation

* Unlike the illustration in Netter’s Atlas, the Lt. subclavian artery on this patient is considerably higher on the arch of the aorta than the Rt common carotid. The Lt subclavian will not appear until image #5. **Notice the shape of the superior vena cava in image #8. It is not a circle like in image 9 because, as is evident from image 7, it is at the anastomosis of the Rt and Lt brachiocephalic veins.

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Images 8 & 7

Images 8-5

Image #6 is very similar to 7. There is nothing new to identify.

1. Rt brachiocephalic vein 2. Lt brachiocephalic vein3. Brachiocephalic artery4. Lt common carotid artery*5. Lt subclavian artery6. Spine of the Rt scapula (scapular spine)

* Because the Lt common carotid is against the Lt brachiocephalic vein the two blend together.

Reference

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Images 6 & 5

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1. Rt brachiocephalic vein 2. Lt brachiocephalic vein3. Brachiocephalic artery4. Lt common carotid artery5. Lt subclavian artery6. Rt sternoclavicular articulation (joint)7. Rt lamina of a thoracic vertebra (16) (17)8. Rt. pedicle of a thoracic vertebra

9. Rt. subclavian artery10. Rt common carotid artery11. Lt axillary vein*12. Lt subclavian vein13. Lt. internal jugular vein**14. Rt subclavian vein 15. Sternal end of Rt. clavicle

* The left axillary and subclavian veins are showing iodine contrast which is being drip infused into the left median cubital vein. The arms are above the patient’s head. ** At the anastomosis of the internal jugular and subclavian veins. Note the ring of contrast created by the non-iodinated blood from the head dumping iodine contrast into the subclavian vein.

Images 4 & 3

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Images 4-1

1. Rt subclavian artery* (410, 412)(427 ,429)2. Rt subclavian vein**3. Rt internal jugular vein4. Rt common carotid artery5. Lt common carotid artery6. Lt subclavian artery***

7. Shaft of the Lt clavicle8. Lt axillary vein with iodine contrast9. Rt & Lt common carotid arteries10. Rt & Lt internal jugular veins11. Apex of Rt lung (plural = apices)12. Acromion process of Lt scapula13. Trachea14. Esophagus

* The circular part of the Rt subclavian artery (in the mediastinum) has been seen in previous sections. Now we see the lateral part of the artery after it crossed the apex of the lung and dropped back into view on this section, as it heads toward the axillary artery.** Compare the relationship of the subclavian artery and vein to plate 412 (429). The arrow (#2) points to the area where a subclavian (central venous) catheter is punctured.*** Unlike the Rt side, the lateral portion of the Lt subclavian does not come into view in this study.

Reference 4

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Images 2 & 1

1. Superior vena cava 2. Arch of Azygos vein* (226, 234)(230, 238)3. Azygos vein4. Hemiazygos vein5. Trachea6. Esophagus

7. Parietal pleura (228)(232)8. Visceral pleura** (192-194)(196-198)9. Rt intervertebral foramen10. Ascending aorta11. Descending aorta12. Pulmonary vessels***

* Where the azygos turns anteriorly and joins the SVC. The circular structure in the middle area of this arch is probably an enlarged lymph node. See plate 235 (239).** The pleural lining are not seen on this study, and are not normally identifiable unless there is pleural thickening or an effusion. But we know they are there.*** Arteries and veins above the hilum of the left lung.

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Images 10 & 11

Images 10-13

1. Superior vena cava 2. Ascending aorta3. Descending aorta4. Lt pulmonary artery*5. Carina of the trachea (198, 199) (202,203)

6. Rt main bronchus (main stem)7. Rt superior lobar bronchus8. Tertiary (3rd level or segmental) bronchi9. Lt pulmonary artery10. Rt pulmonary artery** (202) (206)

Reference

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Images 12 & 13

1. Superior vena cava2. Ascending aorta3. Rt pulmonary artery4. Pulmonary trunk* 5. Lt pulmonary artery

6. Azygos vein7. Pulmonary trunk8. Esophagus

* At this level the right pulmonary artery is just arising from the pulmonary trunk. In image 15 (#7) the trunk is clearly seen, differentiated from the artery.

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Images 14 & 15

Images 14-17

1. Auricle of Rt atrium (208) (212) 2. Rt pulmonary artery*3. Lt atrium4. Pulmonary trunk

5. Aortic sinus (root of the aorta)** (219) (223)6. Lt coronary artery (212, 215) (226-219)7. Lt (superior & inferior pulmonary) pulmonary veins (210-213) (214-217)8. Thoracic aorta***

* At this level we see the last remnant of the Rt pulmonary artery. Notice that the emerging Lt atrium (#3) looks similar to the Rt pulmonary artery in image 15, but is in a different position.** The Rt coronary artery (#5) identifies this as the area of the cusps of the valves known as the aortic sinus or root of the aorta. (219)(223)***At the level of the aortic sinus the descending aorta becomes the thoracic or descending thoracic artery.

Reference

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Images 16 & 17

Another Look

3D image of the thorax. Can you identifythe pulmonary vessels. Click for the legend.

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1. Rt pulmonary artery2. Lt pulmonary artery3. Pulmonary trunk4. Ascending aorta5. Rt pulmonary vein6. Lt pulmonary vein 7. Thoracic aorta

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Another Look: 3D Thorax

1. Rt atrium 2. Rt ventricle3. Lt atrium4. Lt ventricle

The divisions between the chambers of the heart become a bit vague, especially on image 19, but there is no doubt where they are.

A good mental exercise is to identify the structureson previous images that gave rise to each of thechambers, then look back on those images to appreciate why the chambers are where they are.

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Images 18 & 19

Images 18-21

1. Rt atrium 2. Lt atrium3. Rt ventricle4. Lt ventricle5. Rt atrioventricular septum6. Lt atrioventricular septum7. Interatrial septum8. Interventricular septum

On image 21 the atria are receded, asthe ventricles dominate.

Reference

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Images 20 & 21

1. Rt ventricle 2. Lt ventricle3. Interventricular septum4. Inferior vena cava (216) (220)5. Coronary sinus (210, 216) (214, 220)6. Esophagus

7. Liver8. Dome of the Lt hemidiaphragm*9. Pericardial sac (pericardium) (211, 214, 215) (215, 218, 219)* The hazy appearance of the dome and the pulmonary vasculature in the base of the Lt. lung are seen together due to the partial volume effect. This is a good demonstration of two separate structures imaged in a one cm cut thickness.

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{1 cm cutthickness

Dome of diaphragm

Pulmonary vasculature

Images 22 & 23

Images 22-25

1. Rt ventricle 2. Lt ventricle3. Posterior interventricular branch of the Rt coronary artery (Posterior descending artery) (212) (216)4. Spleen

5. Stomach6. Intrahepatic inferior vena cava7. Abdominal aorta

The lung tissue in image 25, deep in the posteriorcostophrenic recess, has been windowed to bestdemonstrate lesions therein, which is why the water density organs of the abdomen appeardifferent than they did at this level in the Abdomen unit.

Reference

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Images 24 & 25

Another Look

This double windowed image of the thorax utilizes a cut and paste type of functionto combine a lung window and water density window in a single image. The disadvantage is a loss of spatial resolution at the edges of the lung fields. Can you identify the mediastinal structures? Click for the legend.

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1. Superior vena cava 2. Ascending aorta3. Rt pulmonary artery4. Descending aorta5. Lt pulmonary artery

Another Look: Double Window