Internal laryngeal nerve runs along which border of Pharyngeal muscle ?
**Core Concept**
The internal laryngeal nerve is a branch of the superior laryngeal nerve, which itself is a branch of the vagus nerve. This nerve provides sensory innervation to the mucous membrane of the larynx above the vocal folds, including the epiglottis, the valleculae, and the posterior part of the tongue. The internal laryngeal nerve is closely associated with the cricothyroid muscle.
**Why the Correct Answer is Right**
The internal laryngeal nerve runs along the anterior border of the cricothyroid muscle. This muscle is located in the larynx and is involved in the regulation of pitch during speech and singing. The internal laryngeal nerve is closely related to the cricothyroid muscle because it provides sensory innervation to the area where the muscle is located. The nerve enters the larynx through the thyrohyoid membrane and runs along the anterior border of the cricothyroid muscle.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the internal laryngeal nerve does not run along the posterior border of the cricothyroid muscle. The posterior border of the cricothyroid muscle is actually related to the external laryngeal nerve, which is another branch of the superior laryngeal nerve.
**Option B:** This option is incorrect because the internal laryngeal nerve does not run along the medial border of the cricothyroid muscle. The medial border of the cricothyroid muscle is not directly related to the internal laryngeal nerve.
**Option C:** This option is incorrect because the internal laryngeal nerve does not run along the lateral border of the cricothyroid muscle. The lateral border of the cricothyroid muscle is not directly related to the internal laryngeal nerve.
**Option D:** This option is incorrect because the internal laryngeal nerve does not run along the inferior border of the cricothyroid muscle. The inferior border of the cricothyroid muscle is not directly related to the internal laryngeal nerve.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the internal laryngeal nerve provides sensory innervation to the mucous membrane of the larynx above the vocal folds, which is crucial for protecting the airway during intubation and other airway procedures.
**Correct Answer: A. The internal laryngeal nerve runs along the anterior border of the cricothyroid muscle.**