Surface Markings of Thorax.pptx

On the front of the thorax the most important vertical lines are the midsternal, the middle line of the sternum; and the mammary, or, better midclavicular, which runs vertically downward from a point midway between the center of the jugular notch and the tip of the acromion

1. Thorax Surface Markings Dr Mathew Joseph MBBS, MD(AIIMS), BCC(Palliative Medicine) Assistant Professor Department of Anatomy Amala Institute of Medical Sciences, Thrissur

2. S urface Landmarks

3. Suprasternal notch : This is felt at the superior border of the sternum. Sternal angle : This is the joint between the manubrium sterni and the body of the sternum. This can be felt as a prominent ridge as we move from the suprasternal notch below over the manubrium sternum at the junction between manubrium and body of sternum. This joint also corresponds to the articulation of the 2nd costal cartilage to the sternum. Counting of ribs : This can be initiated by identifying the manubriosternal angle as this corresponds to the 2nd rib. Then continue counting ribs downwards and laterally. Costal margin : This is a continuous bony margin formed by the joining of the sternal end of the 7th to 10th ribs to one another via the costal cartilages. Subcostal angle : This is the angulation between the two costal margins (right and left).

4. Midsternal line : Line drawn through the middle of the sternum. Midclavicular line : Drawn through the midpoint of the medial and lateral ends of the clavicle. This usually passes through the nipple.

5. Anterior axillary line : This line is drawn vertically at the plane of anterior axillary fold. Posterior axillary line : This line is drawn at the plane of the posterior axillary fold. Midaxillary line : This line passes from the apex of the axilla between the anterior and the posterior axillary folds.

6. HEART SURFACE ANATOMY

7. The heart anatomically can be shown in four borders. They are the right, left, upper and lower margins. They can be drawn by identifying the following points: Point A : Marked on the right 3rd costal cartilage by the side of the right sternal margin. Point B : Marked on the left 2nd intercostal space by the side of the left sternal margin. Point C : Right 6th costal cartilage joining the sternum. Point D : Left 5th intercostal space just medial to the midclavicular line. Upper border is formed by the joining of the points A and B. Lower border is formed by the joining of the points C and D. Right border is formed by the joining of the points A and C by a curved line. Convexity is maximum in the 4th intercostal space, about 3.7 cm to 4 cm from the midline. Left border is formed by the joining of the points B and D. BORDERS OF THE HEART

8. APPLIED ANATOMY By drawing/identifying the borders of the heart, it is possible to percuss the borders and be able to identify the enlargement of the heart. This also helps in putting the leads of the electrocardiogram (ECG) and continuous cardiac monitoring. The area bounded by the borders of the heart is called as the precordial area .

9. Apex Beat 1) This is the farthest point of the heart. This is positioned at the left 5th intercostal space, just medial to the midclavicular line. 2) This is approximately 9 cm from the midsternal line.

10. APPLIED ANATOMY This is the most commonly accessed part of the heart during clinical examination. The heart beat is felt in this position. The apex beat which can be palpated and auscultated by using a stethoscope is due to the vortex like motion of the left ventricle.

11. Orifices of the Heart These are mainly the valvular openings of the heart. They are the tricuspid, mitral, pulmonic and the aortic valvular areas. 1) The tricuspid valve is situated behind the sternum in a vertical plane extending from the 4th to the 5th intercostal space. It is 4 cm long and vertically placed (T). 2) The mitral valve is situated behind the left margin of the sternum at the level of the 4th costal cartilage (M). 3) The pulmonary valve orifice is situated at the level of the left 3rd costal cartilage and partly behind the sternum. It is horizontally placed and is 2.5 cm long (P). 4) The aortic valve is very close to the pulmonary valve . It is situated in the 3rd intercostal space behind the left half of the sternum with an inclination downwards and medially (A).

12. Auscultatory Areas of the Heart There are mainly four valves of the heart. They are the mitral, tricuspid, aortic and the pulmonary valve. 1. The tricuspid valve can be heard at the left lower part of the sternum in the 5th intercostal space (T). 2. The mitral valve can be heard in the left 5th intercostal space near the apex beat (M). 3. The pulmonary valve is in the left 2nd intercostal space near the lateral end of the sternum (P). 4. The aortic valve is in the right 2nd intercostal space near lateral end of the sternum (A). 5. The left 3rd intercostal space near the lateral border of the sternum is also called the neo aortic or 2nd aortic (A2) area as, some aortic valvular pathologies such as the murmur of aortic valve incompetence is better heard here.

13. APPLIED ANATOMY Learning to identify the auscultatory areas is important as we regularly auscultate these areas to confirm the normal heart sounds and be able to diagnose the different murmurs created due to the valvular abnormalities such as mitral valve regurgitation, aortic stenosis, etc. The auscultatory areas might differ in their position in rare cases as dextrocardia and lung diseases which push the heart toward the opposite side. The best position to auscultate the heart is in the sitting position. This is because the heart is closer to the anterior thoracic wall and the sounds will be heard clearly than in supine position as the heart falls away from the thoracic wall.

14. PLEURA & LUNGS SURFACE ANATOMY

15. Cervical Pleura Cervical pleura are drawn as an inverted V shape about 1 inch above the medial third of the clavicle in the neck (A).

16. Costal Pleura Right side : 1) The anterior margin extends as a vertical line over the midsternal line from the suprasternal margin up to the xiphisternal joint (BC). 2) The inferior margin is drawn from the xiphisternal joint to cross the 8th rib in the midclavicular line, 10th rib in the midaxillary line (CDE) and the 12th rib in the paravertebral line (2 cm lateral to the spinous process of the 12th thoracic vertebra) (IJ)] .

17. Costal Pleura Left side : The anterior margin extends as a vertical line over the midsternal line from the suprasternal margin up to the 4th costal cartilage (BF). 2 ) Then it deviates to the left along the left lateral sternal border up to the 6th costal cartilage (FG). 3 ) The inferior margin is drawn from the 6th costal cartilage to meet the 8th rib in the midclavicular line, 10th rib in the midaxillary line (GHI) and the 12th rib in the paravertebral line (IJ) .

18. Both Sides The posterior margin is drawn as a vertical line from the spinous process of the 7th cervical vertebra to the 12th thoracic vertebra. The line is 2 cm lateral to the spinous processes of the vertebrae. (KJ) Costal Pleura

19. APPLIED ANATOMY Pleurocentesis is an invasive procedure done in order to draw pleural fluid in cases of pleural effusion for evaluation of the effusion also as treatment if the effusion is large. This is usually done in the intercostal space along the superior surface of the lower rib. The level of intercostal space is determined by the level of the fluid by X-ray. The level of the effusion should be confirmed on the basis of diminished or absent sounds on auscultation, dullness to percussion, and decreased or absent fremitus. The needle should be inserted one or two intercostal spaces below the level of the effusion, 5–10 cm lateral to the spine (in the space between the scapular line and midline (posteriorly). To avoid intra-abdominal injury, the needle should not be inserted below the 9th rib.

20. Lungs Apex of the lungs : is drawn in the neck about 2.5 cm above the medial 3rd of the clavicle along the pleural reflection (A)

21. Right lung : ▪ The anterior margin extends as a vertical line over the midsternal line from the suprasternal margin up to the xiphisternal joint (BC). ▪ The inferior margin is drawn from the xiphisternal joint to cross the 6th rib in the midclavicular line, 8th rib in the midaxillary line ( CDE) and the 10th rib in theparavertebral line ( IJ ).

22. Left lung : 1) The anterior margin extends as a vertical line over the midsternal line from the suprasternal margin up to the 4th costal cartilage (BF). Then it deviates to the left along the left lateral sternal border. From here the line curves 3.5 cm lateral to the lateral sternal border and then reach the 6th costal cartilage (FG). 2) The inferior margin is drawn from the xiphisternal joint to cross the 6th rib in the midclavicular line, 8th rib in the midaxillary line (GHI) and the 10th rib in the paravertebral line (IJ) .

23. Lungs: Both sides The posterior margin is drawn as a vertical line from the spinous process of the 7th cervical vertebra to the 10th thoracic vertebra. The line is 2 cm lateral to the spinous processes of the vertebrae (KJ) .

24. Root of Lungs 1) These are marked in prone position. 2) Mark the spines of 4th, 5th and 6th thoracic vertebrae. 3) Mark a vertical oval area about 2.5 cm lateral to the spines mentioned above (midway between the spines and medial border of the scapula).

25. Fissures of the lung These fissures cut through the lung till the hilum into three lobes on the right lung and two lobes on the left lung. Oblique fissure : This can be drawn as an oblique line starting from the 2nd thoracic vertebra posteriorly to meet the 6th rib in the midclavicular line anteriorly. This fissure is present in both the lungs. (OF) Horizontal fissure : Drawn as a horizontal line from the point where the oblique fissure meets the midaxillary line to the midsternal line along the 4th costal cartilage. This is present in the right lung . (HF) Hence the right lung is divided into three lobes by the oblique and the horizontal fissures. The left lung is divided into two lobes by the oblique fissure only

26. APPLIED ANATOMY Orientation of the lobes of the lung to the thoracic surface: The oblique fissure because of its obliquity projects the upper lobe to the anterior thoracic wall and the lower lobe to the posterior thoracic wall. Hence when the anterior thoracic wall is palpated and auscultated for respiratory sounds, the student should have the upper lobe in mind and similarly the lower lobe when examining the posterior thoracic wall.

27. ARTERIES OF THORAX

28. Ascending Aorta The aorta is the outlet of the left ventricle. It is marked by: 1) A point on the left of the midsternal line at the 3rd costal cartilage (A). 2) A point to the 2nd costal cartilage on the right side at the border of the sternum (B). 3) The direction of the ascending aorta is from the left to the right and upwards.

29. Arch of the Aorta The arch of the aorta is the continuation of the ascending aorta. It is marked by: 1) A point on the right 2nd costal cartilage at the lateral border of the sternum (B). 2) A point on the midsternal line 2.5 cm below the jugular notch (C). 3) A point of the left 2nd costal cartilage on the lateral border of the sternum (D). 4) Join B, C and D by a double line of 2 cm width.

30. Descending Thoracic Aorta 1) The descending aorta is the continuation of the arch of the aorta. It is marked by: 2) A point on the left 2nd costal cartilage at the lateral border of the sternum (D). 3) A point in the midline, 2 cm above the transpyloric plane(E). 4) Join D and E by double lines 2 cm apart.

31. Innominate Artery, Left Common Carotid Artery and Left Subclavian Artery 1) The innominate artery (brachiocephalic artery) arises in the midline from the arch of the aorta (A) and extends to the right sternoclavicular joint (B). 2) To the left of this is the origin of the left common carotid artery (C) which extends to the left sternoclavicular joint. 3) Then mark a point to the left of left common carotid artery. Mark the left sternoclavicular joint (D). 4) Join the points. This marks the left subclavian artery.

32. Internal Thoracic Artery 1) This is the only branch of the subclavian artery which descends downwards. It is marked by: 2) A point 2 cm above the sternal end of the clavicle (A). 3) A line from the above point, 1 cm lateral to the lateral sternal margin (B). 4) A point at the sternal end of the 6th costal cartilage (C) .

33. APPLIED ANATOMY The ascending aorta and arch of the aorta are some of the common sites of aneurysmal dilatation (disproportionate/abrupt dilatation of a part/segment of a blood vessel). This can cause compression of the adjacent veins, nerves, trachea/bronchi, esophagus and patient will present with corresponding symptoms. Clinically, this can be suspected when we find superior mediastinal widening on percussion, i.e., dullness extending more than half an inch lateral to the sternal border on either side in the 2nd and 3rd intercostal spaces. Differential diagnoses: Thymoma, ectopic thyroid, pulmonary arterial dilatation on the left side, lymph nodes.

34. APPLIED ANATOMY The internal thoracic artery needs ligation in cases of cardiac bypass and breast procedures. The best areas to access are in the 2nd and 3rd intercostal spaces as these are the widest and the artery can be accessed at 1 cm lateral to the sternal margin.

35. VEINS OF THORAX

36. Right Brachiocephalic Vein 1) A point on the right sternoclavicular joint. 2) A point on the right 1st costal cartilage, 1 cm lateral to the lateral sternal margin.

37. Left Brachiocephalic Vein 1) A point on the left sternoclavicular joint. 2) A point on the right 1st costal cartilage, 1 cm lateral to the lateral sternal margin. 3) The direction is from the left to the right and downwards.

38. Superior Vena Cava 1) A point on the right 1st costal cartilage, 1 cm lateral to the lateral sternal margin (A). 2) A point on the upper border of the 3rd costal cartilage, 1 cm parallel to the lateral sternal margin (B). 3) Join the points A and B by two parallel lines 2 cm apart .

39. TRACHEA AND OESOPHAGUS

40. Trachea Anteriorly , the trachea can be marked as follows: 1) Mark a point below the cricoid cartilage (A). 2) Mark a point 1 cm to the right of the midpoint of the sternal angle (B). 3) Join these two points by two parallel lines 2 cm apart.

41. Trachea Posteriorly , the trachea can be marked as follows: 1) A point on the spinous process of the 6 th cervical vertebra (A). 2) A point on the 4th thoracic spine (B). 3) This corresponds to the sternal angle on the front. 4) Join the above two points by two parallel lines 2 cm apart.

42. Esophagus The surface marking is done on the back of the trunk. 1) A point on the 7th cervical spine. The spine of the 7th cervical vertebra is the most prominent spine on the back of the neck (A). 2) A point 2.5 cm lateral to the 9th thoracicvertebral spine. Both the points are marked on the left side (B). 3) Join both the points with two parallel lines around 2 cm apart.

43. Thoracic Duct 1) Mark a point 2 cm above and 2 cm right lateral to the transpyloric plane from the midline (A). 2) Mark a point at the 3rd right lateral chondrosternal margin (B). 3) Mark a point at the midpoint of the sternal angle (C). 4) Mark a point to the 2nd left chondrosternal margin (D). 5) Mark a point 2 cm from the midline and 2.5 cm above the left clavicle (E). 6) Mark a point at the left sternoclavicular joint (F). 7) Join A through F.

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