Human Anatomy Vol 1

THORAX

infrasternal or subcostal angle. The depression in the
angle is also known as the epigastric fossa.
The xiphoid (Greek sutord) process lies in the floor
of the epigastric fossa. At the apex of the angle, the
xiphisternal joint may be felt as a short transverse
ridge. It lies at the level of the upper border of the
ninth thoracic vertebra (Fig. 12.1).
4 Costal cartilages:The second costal (Latin rib) cartilage
is attached to the sternal angle. Tlrre seoenth cartilage
bounds the upper part of the infrasternal angle. The
lateral border of the rectus abdominis or the linea
semilunaris joins the costal margin at the tip of the
ninth costal cartilage. The tenth costal cartilage forms
the lower part of the costal margin (Figs 12.1 and
12.2).
5 Rlbs; The scapula overlies the second to seventh ribs
on the posterolateral aspect of the chest wall. The
tenth rib is the lowest point, lies at the level of the
third lumbar vertebra. Though the eleventh rib is
longer than the twelfth, both of them are confined to
the back and are not seen from the front (Fig. 12.2).
6 Thoracic uertebral spines; The first prominent spine felt
at the lower part of the back of the neck is that of the
seaenth ceraical oertebra or aertebraprominens. Below this
spine, all the thoracic spines canbepalpated along the
posterior median line (Fig. 12.3). The third thoracic
spine lies at the level of the roots of the spines of the
scapulae. The seventh thoracic spine lies at the level
of the inferior angles of the scapulae.

Sott Tissue londmorks

I The nipple: The position of the nipple varies

considerably in females, but in males it usually lies

in the fourth intercostal space about^10 cm from the

midsternal line (Fig. 12.4).

2 Apexbent:Itis a visible and palpable cardiac impulse

in the left fifth intercostal sPace^9 cm from the

midsternal line, or medial to the midclavicular line.

3 Trachea: It is palpable in the suprasternal notch

midway between the two clavicles.

Manubrium

Body of sternum

Xiphisternum

Costal cartilages

First rib

4th thoracic

vertebra

Sth rib

9th thoracic

vertebra

1 Oth rib

12th thoracic

vertebra

12th rib

Fig. 12.2: Shape and construction of the thoraciccage as seen

from the lateral side

1 Oth rib

12th rib

Scapular line

Fig. 12.3: Shape and construction of the thoracic cage as seen

from behind

Fig. 12.4: Soft tissue landmarks

Midclauiculsr or lateral oertical or ffiafiffiuty plane: Itis

a vertical plane passing through the midinguinal

point, the tip of the ninth costal cartilage and middle

of clavicle (Fig. 12.5).

Midaxillaty line: Itpasses vertically between the two

folds of the axilla (Fig. 12.5).

Scapular line: It passes vertically along the inferior

angle of the scapula.