Cailaginous pa of external auditory canal is
**Core Concept**
The external auditory canal (EAC) is a narrow, tortuous passage that connects the outer ear to the tympanic membrane. The EAC is composed of three distinct parts: the outer cartilaginous part, the middle osseous part, and the inner membranous part. The cartilaginous part is critical for providing flexibility and mobility to the EAC.
**Why the Correct Answer is Right**
The cartilaginous part of the EAC is made up of hyaline cartilage, which is a flexible and lightweight connective tissue. This cartilaginous structure allows for the EAC to change shape and accommodate the movement of the pinna (external ear). The cartilage in the EAC is also richly innervated with sensory nerve fibers, providing important feedback about the position and movement of the ear. The cartilaginous part of the EAC is approximately 1-2 cm in length and is located at the anterior aspect of the EAC.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the osseous part of the EAC is located posteriorly and is made up of bone, not cartilage.
* **Option B:** This option is incorrect because the membranous part of the EAC is located internally and is a thin, fibrous layer that separates the EAC from the middle ear cavity.
* **Option C:** This option is incorrect because the tympanic membrane is located at the end of the EAC and is not part of the cartilaginous structure.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the cartilaginous part of the EAC is the most common site for external ear infections, such as otitis externa, due to its rich blood supply and innervation.
**Correct Answer:** C.