Question

Which of the following is most suitable description for trachea?

• A. Straight tube, extending upto the mid-thoracic cavity and divides at the level of 5^th thoracic vertebra.
• B. Straight tube, extending upto the mid-thoracic cavity and divides at the level of 3^rd thoracic vertebra.
• C. Straight tube, extending upto the neck and divides at the level of 5^th cervical vertebra.
• D. Curved tube, extending upto the mid-thoracic cavity and divides at the level of 5^th thoracic vertebra.

Answer 1

Answer: (A)

Trachea : It is a straight tube that extends upto the mid-thoracic cavity and divides at the level of 5^th thoracic vertebra into 2 branches: a right and left primary bronchi.
Branching in trachea leads to primary bronchi $\to$ secondary bronchi $\to$ tertiary bronchi and bronchioles $\to$ terminal bronchioles $\to$ alveoli (numerous very thin, irregular-walled and vascularised bag-like structures).
The tracheae, bronchi (primary, secondary and tertiary) and initial bronchioles are supported by incomplete cartilaginous rings.