Human Anatomy Vol 1

,

a

I

INIRODUCIION

Trachea or windpipe is the patent tube for passage of
air to and from the lungs. In contrast, oesophagus lying
behind the trachea opens onlywhile drinking or eating.
Thoracic duct brings the lymph from major part of the
body to the root of the neck.

The trachea (Latin air aessel) is a wide tube lying more

or less in the midline, in the lower part of the neck and

in the superior mediastinum. Its uPPer end is con-

tinuous with the lower end of the larynx. The trachea

in the neck is covered by the isthmus of the thyroid

gland and acts as a shield for trachea. At its lower end

the trachea ends by dividing into the right and left

principal bronchi (Fig. 20.1).

The trachea is 10 to 15 cm in length. Its external

diameter measures about 2 cm in males and about 1.5

cm in females. The lumen is smaller in the living than

in the cadaver. It is about 3 mm at one year of age.

During childhood it corresponds to the age in years/

with a maximum of about^12 mm in adults, i.e. it

increases 1 mm per year tp to^12 years.

The upper end of the trachea lies at the lower border

of the cricoid cartilage, opposite the sixth cervical

vertebra. In the cadaver its bifurcated lower end lies

at the lower border of the fourth thoracic vertebra,

corresponding in front to the stemal angle. However,

in living subjects, in the erect posture, the bifurcation

lies at the lower border of the sixth thoracic vertebra

and descends still further during inspiration.

Over most of its length the trachea lies in the median

plane, but near the lower end it deviates slightly to the

right. As it runs downwards, the trachea Passes slightly

backwards following the curvature of the spine.

-T, Wilder

Relolions of the Thorocic Port

AnteriCIrly

1 Manubrium sterni.

2 Sternothyroid muscles.

3 Remains of the thymus.

4 Left brachiocephalic and inferior thyroid veins.

5 Aortic arch, brachiocephalic and left common carotid

arteries.

6 Deep cardiac plexus (seeFig.19.9).

7 Some lymph nodes.

Cricoid cartilage

Trachea

Brachiocephalic

trunk

Thyroid cartilage

Thyroid gland

Oesophagus

Left common

carotid artery

Left subclavian

artery

Arch of aorta

Left principal

bronchus

Oesophagus ---:

280

Fig. 20.1 : Trachea and its relations