Human Anatomy Vol 1

Horizontal

fissure

Oblique

fissure

Lower

lobe

THORAX

Upper lobe

Trachea

Apex

Costal surface

Anterior

border

Oblique

fissure

Lower

lobe

Base

Middle lobe Lingula

Base lnferior border

Fig. 16.1: The trachea and lungs as seen from the front

Right vagus nerve

Oesophagus

Trachea

Arch of

azygos vern

Hilum

Oesophagus

Pulmonary

ligament

Posterior

lnferior vena cava border

Fig. 16.2: lmpressions on the mediastinal surface of the right
lung

pericardium are not covered by the lung in the region

of this notch.

The posterior border is thick and ill defined. It

corresponds to the medial margins of the heads of the

ribs. It extends from the level of the seventh cervical

spine to the tenth thoracic spine.

The inferior border separates the base from the costal

and medial surfaces.

The costal surface is large and convex. It is in contact

with the costal pleura and the overlying thoracic wall.

The medial surface is divided into a Posterior or

vertebral parl, and an anterior or mediastinal part. The

vertebral part is related to the vertebral bodies,

intervertebral discs, the posterior intercostal vessels and

the splanchnic nerves (see Figs 15.1 and 15.2). The

mediastinal part is related to the mediastinal septum,

and shows a cardiac impression, the hilum and a

number of other impressions which differ on the two

sides. Various relations of the mediastinal surfaces of

the two lungs are listed in Table 15.1.

Fissures ond Lobes of the Lungs

The right lung is divided into^3 lobes (upper, middle

and lower)by two fissures, oblique and horizontal. The

left lung is divided into two lobes by the oblique fissure

(Fig. 16,.1).

The oblique fissure cuts into the whole thickness of

the lung, except at the hilum. It passes obliquely

downwards and forwards, crossing the posterior

border about 6 cm below the apex and the inferior

border about 5 cm from the median plane. Due to the

oblique plane of the fissure, the lower lobe is more

posterior and the upper and middle lobe more anterior.

1. Right atrium and auricle


2. A small part of the right
   ventricle


3. Superior vena cava


4. Lower part of the right
   brachiocephalic vein


5. Azygos vein


6. Oesophagus


7. lnferior vena cava


8. Trachea


9. Right vagus nerue
   10.Right phrenic nerve


10. Left ventricle, left auricle,
    infundibulum and adjoining
    part of the right ventricle


11. Pulmonary trunk


12. Arch of aorta


13. Descending thoracic aorta


14. Left subclavian artery


15. Thoracic duct


16. Oesophagus


17. Left brachiocephalic vein


18. Left vagus nerue


19. Left phrenic nerve
    1 1. Left recurrent laryngeal nerve

Right

brachiocephalic

vetn

Ascending

aorta

Superior

vena cava

Anterior border

lmpression of

right atrium

Right phrenic

nerve

Oesophagus

Thoracic duct

Left recurrent

laryngeal nerve

Left vagus nerve

Left superior

intercostal vein

Left ventricle

Trachea

Left subclavian

arlery

Left common

carotid artery

Arch of aorta

Pulmonary

trunk

Left phrenic

nerve

Cardiac notch

Descending

thoracic aorta

Oesophagus

Fig. 16.3: lmpressions on the mediastinal surface of the left lung