Human Anatomy Vol 1

THORAX

Fig.21.12= Posteroanterior view of the thorax

cartilages are not seen unless these are calcified. The

medial borders of the scapulae may overlap the

periphery of the lung fields.

Tlocheo

Trachea is seen as air-filled shadow in the midline of

the neck. It lies opposite the lower cervical and upper

thoracic vertebrae (Fig. 21.12).

Diophrogm

Diaphragm casts dome-shaped shadows on the two

sides. The shadow on the right side is little higher than

on the left side. The angles where diaphragm meets

the thoracic cage are the costophrenic angles-the right

and the left. Under the left costophrenic angle is mostly

the gas in the stomach, while under the right angle is

the smooth shadow of the liver.

Lungs

The dense shadows are cast by the lung roots due to

the presence of the large bronchi, pulmonary vessels,

bronchial vessels and lymph nodes. The lungs readily

permit the passage of the X-rays and are seen as

translucent shadows during full inspiration. Bothblood

vessels and bronchi are seen as series of shadows

radiating from the lung roots. The smaller bronchi are

not seen. The lung is divided into three zones-upper

zone is from the apex till the second costal cartilage.

Middle zone extends from the second to the fourth

costal cartilage. It includes the hilar region. Lower zone

extends from the fourth costal cartilage till the bases of

the lungs.

Medioslinum

Shadow is produced by the superimpositions of

structures in the mediastinum. It is chiefly produced

by the heart and the vessels entering or leaving the

heart. The transverse diameter of heart is half the

transverse diameter of the thoracic cage. During

inspiration, heart descends down and acquires fubular

shape. Right border of the mediastinal shadow is

formed from above downwards by right brachio-

cephalic vein, superior vena cava, right atrium and

inferior vena cava. The left border of mediastinal

shadow is formed from above downwards by aortic

arch (aortic knuckle), left margin of pulmonary trunk,

left auricle and left ventricle. The inferior border of the

mediastinal shadow blends with the liver and

diaphragm.

Tomography is a radiological technique by which

radiograms of selected layers (depths) of the body can

be made. Tomography is helpful in locating deeply

situated small lesions which are not seen in the usual

radiograms.

a

a

a

a

Anteroposterior diameter of inlet of thorax-S cm.

Transverse diameter of inlet of thorax-1O cm.

Suprasternal notch-T2 vertebra.

Sternal angle-disc between T4 and T5 vertebra. 2nd

costal cartilage articulates with the sternum.

Xiphisternal joint-T9 vertebra.

Subcostal angle-between sternal attachments of 7th

costal cartilages.

Vertebra prominence

-7

th cervical spine.

Superior angle of scapula-level of T2 spine.

Root of spine of scapula-level of T3 spine.

Inferior angle of scapula-level of T7 spine.

Length of oesophagus-2S cm:

• Cervical part-4 cm.


• Thoracic part-20 cm.


• Abdominal part-1.25 cm.


• Beginning of oesophagus-C6 vertebra.


• Termination of oesophagus-T11 vertebra.
  Beginning of trachea-C6 vertebra:


• Length of trachea-10-15 cm.


• Bifurcation of trachea-upper border of T5
  vertebra.


• Length of right principal bronchus-2.S cm.
  
  
  • Length of left principal bronchus-S cm.
  
  
  
  

a

a

a

a

a

a

a

I

mebooksfree.com