Human Anatomy Vol 1

THORAX

lnternal thoracic vessels

Left brachiocephalic vein

Brachiocephalic trunk

Left common carotid artery

Left subclavian artery

Left recurrent laryngeal nerve

Oesophagus and thoracic duct

Pericardial branches, to the posterior surface of the

pericardium.

Mediastinal branches, to lymph nodes and areolar

tissue of the posterior mediastinum.

Superior phrenic arteries to the posterior part of the

superior surface of the diaphragm. Branches of these

arteries anastomose with those of the musculo-

phrenic and pericardiacophrenic arteries.

The wide pulmonary trunk starts from the summit of
infundibulum of right ventricle. Both the ascending
aorta and pulmonary trunk are enclosed in a common
sleeve of serous pericardium, in front of transverse
sinus of pericardium. Pulmonary trunk carrying
deoxygenated blood, overlies the beginning of
ascending aorta. It courses to the left and divides
into right and left pulmonary arteries under the
concavity of aortic arch at the level of sternal angle
(Figs 19.2 and 19.3).
The right pulmonary artery courses to the right
behind ascending aorta, and superior vena cava and
anterior to oesophagus tobecome part of the root of the
lung. It gives off its firstbranch to the upper lobe before
entering the hilum. Within the lung the artery descends
posterolateral to.the mainbronchus and divides like the
bronchi into lobar and segmental arteries.
The left pulmonary artery passes to the left anterior
to descending thoracic aorta to become part of the root

Right brachiocephalic vein

Right phrenic nerve

Trachea

Right vagus nerve

of the left lung. At its beginning, it is connected to the

inferior aspect of arch of aorta by ligamentum arteriosus,

a remnant of ductus arteriosus. Rest of the course is same

as of the right branch.

Superior vena cava is the second largest vein of

the body.

Yena azygos brings the venous blood from the

posterior parts of thoracic and abdominal wall.

Aorta is the largest elastic artery of the body. It

takes oxygenated blood to all parts of the body

except the lungs.

There is a gradual transition from its elastic nature

to muscular nature of its branches.

Pulmonary trunk arises from the right ventricle.

It soon divides into right and left pulmonary

arteries which carry deoxygenated blood from

right ventricle to the lungs for oxygenation.

Pulmonary trunk and ascending aorta develop

from a common source, the truncus arteriosus.

There is triple relationship between these two

vessels:

• Close to heart, pulmonary trunk lies anterior to
  ascending aorta.


• At upper border of heart, pulmonary trunk lies
  to the left of ascending aorta.


• A little above this, the right pulmonary artery
  lies posterior to the ascending aorta.

lntercostal vessels

Fig" 19.10: Transverse section of thorax passing through the third thoracic vertebra