In the right lung, the horizontal fissure passes from
the anterior border up to the oblique fissure and
separates a wedge-shaped middle lobe from the upper
lobe. The fissure runs horizontally at the level of the
fourth costal cartilage and meets the oblique fissure in
the midaxillary line.
The tongue-shaped projection of the left lung below
the cardiac notch is called the lingula.It corresponds to
the middle lobe of the right lung.
The lungs expand maximally in the inferior direction
because movements of the thoracic wall and diaphragm
are maximal towards the base of the lung. The presence
of the oblique fissure of each lung allows a more
uniform expansion of the whole lung.
Suiloce Morking of lhe Lung/Viscerol Pleuro
The apex of the lung coincides with the cervical pleura,
and is representedby a line convex upwards rising 2.5 cm
above the medial one-third of the clavicle (see Fig.27.2).
The anterior border of the right lung coruesponds very
closely to the anterior margin or costomediastinal line
of the pleura and is obtained by joining:
a. A point at the sternoclavicular joint,
b. A point in the median plane at the sternal angle,
c. A point in the median plane just above the
xiphisternal joint.
The anterior border of the left lung corresponds to the
anterior margin of the pleura up to the level of the
fourth costal cartilage.
In the lower part, it presents a cardiac notch of
variable size. From the level of the fourth costal
cartilage, it passes laterally for 3.5 cm from the sternal
margin, and then curves downwards and medially to
reach the sixth costal cartilage 4 cm from the median
p1ane. In the region of the cardiac notch, the peri-
cardium is covered only by a double layer of pleura.
The area of the cardiac notch is dull on percussion and
is called the area of superficial cardiac dullness.
The lower border of each lung lies two ribs higher than
the pleural reflection. It crosses the sixth rib in the
midclavicular line, the eighth rib in the midaxillary line,
the tenth rib at the lateral border of the erector spinae,
and ends 2 cm lateral to the tenth thoracic spine.
The posterior border coincides with the posterior
margin of the pleural reflection except that its lower
end lies at the level of the tenth thoracic spine.
The oblique fissure canbe drawn by joining:
a. A point 2 cm lateral to the third thoracic spine.
b. Another point on the fifth rib in the midaxillary
line.
c. A third point on the sixth costal cartilage 7.5 cm
from the median plane.
The horizontal fissure is represented by a line joining:
a. A point on the anterior border of the right lung at
the level of the fourth costal cartilage.
LUNGSb. A second point on the fifth rib in the midaxillary
line.Rool of the lung
Root of the lung is a short, broad pedicle which connects
the medial surface of the lung to the mediastinum. It is
formed by structures which either enter or come out of
the lung at the hilum (Latin depressiotr). The roots of
the lungs lie opposite the bodies of the fi{th, sixth and
seventh thoracic vertebrae.femfs
The root is made up of the following structures.
L Principal bronchus on the left side, and eparterial
and hyparterial bronchi on the right side.
2 One pulmonary artery.
3 Two pulmonary veins, superior and inferior.
4 Bronchial arteries, one on the right side and two on
the left side.
5 Bronchial veins.
6 Anterior and posterior pulmonary plexuses of
nerves.
7 Lymphatics of the lung.
8 Bronchopulmonary lymph nodes.
9 Areolar tissue.Arongement of Slructules in the Rool
1 From anterior to posterior. It is similar on the two
sides (Fig. 16.4).
a. Superior pulmonary vein
b. Pulmonary artery
c. Bronchus
2 From above downwards. It is different on the two
sides.
Right side
a. Eparterial bronchus
b. Pulmonary artery
c. Hyparterial bronchus
d. h-rferior pulmonary vein
Left side
a. Pulmonary artery
b. Bronchus
c. Inferior pulmonary vemflelofions af the Root
Anterior
'L Common on the two sides
a. Phrenic nerve
b. Pericardiacophrenic vessels
c. Anterior pulmonary plexus
2 On the right side
a. Superior vena cava (Fig.16.2)
b. A part of the right atriurn"