The angle of bifurcation in the structure shown below, is increased in enlargement of ?
A. Right ventricle.
B. Left ventricle.
C. Right atrium.
D. Left atrium.
Ans;D. Left Atrium.
Angle of tracheal bifurcation is increased in enlargement of Left atrium.
- The trachea extends from the lower border of the larynx to the carina, where it bifurcates into the mainstem bronchi.
- The carina is a ridge of cartilage in the trachea that occurs between the division of the two main bronchi.
- This ridge lies to the left of the midline, and runs antero-posteriorly (front to back).
- Normal angle of the tracheal bifurcation is 70 ± 20 degrees .
- With deep inspiration, the tracheal length increases by as much as 2 cm and the angle of the tracheal bifurcation decreases by up to 10 degrees
Left Atrial Enlargement
Left atrium can enlarge in multiple directions:
- It is believed left atrial appendage enlargement occur early . LA enlargemnet seen as a fullness beneath the pulmonary artery shadow.
- LA could also enlarge posteriorly by pushing the esophagus towards the spine.This is visible only in barium swallow.
- Then LA can enlarge either to left or right ( Usually towards right) and reach the right heart border or over shoot it and form the right heart border by itself.This occurs very late in the course.
- The other direction LA goes on to enlarge is superiorly. When LA enlarges superiorly it hits on the left main bronchus and lifts it.This is measured by the widened subcarinal angle which is normally less than 75 degrees.