Question
All are true about the anatomical structure (marked by a box) as shown in the image except:
A. Shorter and wider
B. Angle 25 degree with vertical
C. Aorta arches over
D. Divides into three secondary bronchi
Show Answer
|
Correct Answer » C Explanation |
 |
Ans:C. Aorta arches over
Right bronchus is marked in the image.
Bronchus (main or primary bronchus)
- It is an airway in the respiratory tract that conducts air into the lungs.
- The trachea divides at the carina into two main or primary bronchi, the left bronchus and the right bronchus at the level of the sternal angle and the fifth thoracic vertebra .
- There is a right bronchus and a left bronchus and these bronchi branch into smaller secondary and tertiary bronchi which branch into smaller tubes, known as bronchioles.
- No gas exchange takes place in the bronchi.
Right bronchus:
- The right main bronchus is wider, shorter, and more vertical than the left main bronchus.
- It enters the right lung at approximately the fifth thoracic vertebra.
- The right main bronchus subdivides into three secondary bronchi (also known as lobar bronchi) —the superior, middle and inferior lobe.
- The azygos vein arches over it from behind; and the right pulmonary artery lies at first below and then in front of it.
- The right main stem bronchus takes off at a 20 to 30° angle from the medial axis of the trachea.
- The average length of the adult right main stem bronchus is 2.5 cm and its average diameter is 13 mm.
Left Bronchus:
- It generally takes off at a 40 to 50° angle with respect to the trachea. It is also longer (5 cm), but smaller in diameter (12 mm) than the right main stem bronchus.
- It enters the root of the left lung opposite the sixth thoracic vertebra.
- It passes beneath the aortic arch, crosses in front of the esophagus, the thoracic duct, and the descending aorta, and has the left pulmonary artery lying at first above, and then in front of it.
- The left main bronchus divides into two secondary or lobar bronchi —the superior and the inferior lobe.