Question

Arrange the following structures of olfactory system from outer to inner side of the system:
A. Olfactory bulb
B. Nerve fibre
C. Cilia
D. Nasal Cavity
E. Receptor cells
Choose the correct answer from the options given below:

• A. D - E - A - C - B
• B. E - D - C - B - A
• C. D - C - E - B - A
• D. C - D - E - A - B

Hint:

Always use extreme anatomical landmarks to solve pathway questions: the nasal cavity (D) is obviously the most external, while the olfactory bulb (A) is a brain structure and must be the most internal.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question asks us to arrange the anatomical structures of the human olfactory (smell) system from the outermost external structures to the innermost brain-based structures.

Step 2: Detailed Explanation:

• D. Nasal Cavity: The outermost part of the system is the nasal cavity, through which airborne chemical odorants enter during inhalation.

• C. Cilia: Within the nasal cavity, the odorant molecules bind to the hair-like cilia that project into the olfactory mucosa.

• E. Receptor cells: These cilia are the specialized dendrites of the olfactory receptor cells (bipolar neurons) located in the olfactory epithelium.

• B. Nerve fibre: The axons of these receptor cells gather together to form olfactory nerve fibers, which pass upward through the tiny openings of the cribriform plate.

• A. Olfactory bulb: These nerve fibers terminate and synapse in the olfactory bulb, which is the innermost brain structure of this sequence, located directly beneath the frontal lobe.

• This anatomical progression from outside to inside corresponds to the sequence: D $\rightarrow$ C $\rightarrow$ E $\rightarrow$ B $\rightarrow$ A.

Step 3: Final Answer:
The correct anatomical order from outer to inner structures of the olfactory system is D - C - E - B - A.