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The anterior thorax
descends vertically lateral to the sternal border to the 6th costal cartil-
Landmarks of the anterior thorax include:
age. From these points both pleurae pass posteriorly and in so doing
• The angle of Louis (sternal angle): formed by the joint between the
cross the 8th rib in the mid-clavicular line, the 10th rib in the mid-
manubrium and body of the sternum. It is an important landmark as the pleura passes laterally for a small distance at the 4th costal cartilage and
2nd costal cartilages articulate on either side and by following this line axillary line and finally reach the level of the 12th rib posteriorly.
onto the 2nd rib, further ribs and intercostal spaces can be identified.
The sternal angle corresponds to a horizontal point level with the inter- The lungs (Fig. 10.1)
vertebral disc between T4 and T5. The apex and mediastinal border of the right lung follow the pleural
• The suprasternal notch: situated in the midline between the medial outline. In mid-inspiration the right lung lower border crosses the 6th
ends of the clavicles and above the upper edge of the manubrium. rib in the mid-clavicular line, the 8th rib in the mid-axillary line and
• The costal margin: formed by the lower borders of the cartilages of reaches the level of the 10th rib posteriorly. The left lung borders are
the 7th, 8th, 9th and 10th ribs and the ends of the 11th and 12th ribs. similar to those of the right except that the mediastinal border arches
• The xiphisternal joint: formed by the joint between the body of the laterally (the cardiac notch) but then resumes the course mentioned
sternum and xiphisternum. above.
• The oblique fissure: is represented by an oblique line drawn from a
The posterior thorax point 2.5 cm lateral to the 5th thoracic spinous process to the 6th costal
Landmarks of the posterior thorax include: cartilage anteriorly. The oblique fissures separate the lungs into upper
• The first palpable spinous process is that of C7 (vertebra prominens). and lower lobes.
C1–6 vertebrae are covered by the thick ligamentum nuchae. The • The transverse fissure: is represented by a line drawn horizontally
spinous processes of the thoracic vertebrae can be palpated and counted from the 4th costal cartilage to a point where it intersects the oblique
in the midline posteriorly. fissure. The fissure separates the upper and middle lobes of the right
• The scapula is located on the upper posterior chest wall. In slim sub- lung.
jects the superior angle, inferior angle, spine and medial (vertebral)
border of the scapula are easily palpable. The heart
• The borders of the heart are illustrated by joining the four points
Lines of orientation shown (Fig. 10.2).
These are imaginary vertical lines used to describe locations on the • The apex of the left ventricle corresponds to where the apex beat is
chest wall. These include: palpable. The surface marking for the apex beat is in the 5th intercostal
• The mid-clavicular line: a vertical line from the midpoint of the clav- space in the mid-clavicular line.
icle downwards. • See Fig. 10.2 for optimal sites of valvular auscultation.
• The anterior and posterior axillary lines: from the anterior and poster-
ior axillary folds, respectively, vertically downwards. The great vessels
•The mid-axillary line: from the midpoint between anterior and poster- • The aortic arch: arches antero-posteriorly behind the manubrium.
ior axillary lines vertically downwards. The highest point of the arch reaches the midpoint of the manubrium.
• The brachiocephalic artery and left common carotid artery: ascend
Vertebral levels posterior to the manubrium.
Palpable bony prominences can be used to identify the location of • The brachiocephalic veins: are formed by the confluence of the inter-
important underlying structures. The following bony landmarks and nal jugular and subclavian veins. This occurs posterior to the sterno-
their corresponding vertebral levels are given: clavicular joints.
• Suprasternal notch: T2/3. • The superior vena cava: is formed by the confluence of the left and
• Sternal angle (angle of Louis): T4/5. right brachiocephalic veins between the 2nd and 3rd right costal cartil-
• Superior angle of the scapula: T2. ages at the right border of the sternum.
• Inferior angle of the scapula: T8.
• Xiphisternal joint: T9. The breast
• Subcostal plane (lowest part of the costal margin): L3. The base of the breast (p. 69) is constant, overlying the 2nd to the 6th
ribs and costal cartilages anteriorly and from the lateral border of the
The surface markings of thoracic structures sternum to the mid-axillary line. The position of the nipple is variable
The trachea in the female but in the man it is usually in the 4th intercostal space in
The trachea commences at the lower border of the cricoid cartilage (C6 the mid-clavicular line.
vertebral level). It runs downwards in the midline and ends slightly to
the right by bifurcating into the left and right main bronchi. The bifurca- The internal thoracic vessels
tion occurs at the level of the sternal angle (T4/5). These arteries and veins descend 1 cm lateral to the edge of the
sternum.
The pleura (Fig. 10.1)
The apex of the pleura projects about 2.5 cm above the medial third of The diaphragm
the clavicle. The lines of pleural reflection pass behind the sternoclavicu- In mid-inspiration the highest part of the right dome reaches as far as
lar joints to meet in the midline at the level of the sternal angle. The the upper border of the 5th rib in the mid-clavicular line. The left dome
right pleura then passes downwards to the 6th costal cartilage. The left reaches only the lower border of the 5th rib.

Surface anatomy of the thorax 27