Human Anatomy Vol 1

SURFACE MARKING AND RADIOLOGICAL ANATOMY OF THOBAX

lowerborders. The maximum convexity is about 3.8 cm
from the median plane in the fourth space.
The left border is marked by a line, fairly convex to
the left, joining the left ends of the upper and lower
borders.
Atrioventricular groove is marked by a line drawn
from the sternal end of left 3rd costal cartilage to the
sternal end of right sixth costal cartilage.
The area of the chest wall overlying the heart is called
the precordium.

Surfoce Morking of the Cordioc lves ond

the Auscultotory Areos

Sound produced by closure of the valves of the heart

can be heard using a stethoscope. The sound arising in

relation to a particular valve are best heard not directly

over the valve, but at areas sifuated some distance away

from the valve in the direction of blood flow through

it. These are called auscultatory areas. The position

of the valves in relation to the surface of the body, and

of the auscultatory areas is given in Table 27.7 and

Fig.2r.6.

Aileries

Infen ol Mamrnary ffihorscre) A ry

It is marked by joining the following points (Fi9.27.7).

L A point (^1) cm above the sternal end of the clavicle,
3.5 cm from the median plane.
2 Points marked over the upper 6 costal cartilages at a
distance of 1,.25 cm from the lateral stemal border.
3 The last point is marked in the sixth space 1.25 cm
from the lateral sternal border.
P or)#ry fflur?k
1 First mark the pulmonary valve by a horizontal line
2.5 cm long, mainly along the upper border of the
left 3rd costal cartilage and partly over the adjoining
part of the stemum (Fi9.21,.6).
2 Then mark the pulmonary trunkby two parallel lines
2.5 cm apart from the pulmonary orifice upwards to
the left 2nd costal cartilage.
1 First mark the aortic orifice by a slightly oblique line
2.5 cm long running downwards and to the right
over the left half of the sternum beginning at the level
of the lower border of the left 3rd costal cartilage
(Fig. 21.6).
2 Then mark the ascending aorta by two parallel lines
2.5 cm apart from the aortic orifice upwards to the
right half of the sternal angle (Fig. 21.6).
Areh of the Aorta
Arch of the aorta lies behind the lower half of the
manubrium sterni. Its upper convex border is marked
by a line which begins at the right end of the sternal
Aortic area
Pulmonary area
Pulmonary valve
Aortic valve
Mitral valve
Tricuspid valve
Tricuspid area
Fig. 21 .6: Sudace projection of the cardiac valves. The position
of the auscultatory areas is also shown
M
Table 21.1 : Surface marking of the cardiac valves and the sites of the auscultatory areas (Fig.^21 .6)
Valve

1. Pulmonary


2. Aortic


3. Mitral


4. Tricuspid

Diameter of orifice

2.5 cm

2.5 cm

3cm

4cm

Surface marking

A horizontal line, 2.5 cm long, behind the upper

border of the third left costal cartilage and adjoining

part of the sternum

A slightly oblique line, 2.5 cm long, behind the left

half of the sternum at the level of the lower border

of the left third costal cartilage

An oblique line, 3 cm long; behind the lelt half of

the sternum opposite the left fourth costal cartilage

Most oblique of all valves, being nearly vertical,

4 cm long; behind the right half of the sternum

opposite the fourth and fifth spaces

Auscultatory area

Second left intercostal space

near the sternum

Second right costal cartilage

near the sternum

Cardiac apex

Lower end of the sternum