All the statements given below are true about nerve supply of larynx except

Okay, let's tackle this question about the nerve supply of the larynx. The question is asking which statement is incorrect regarding the nerve supply. First, I need to recall the anatomy of the laryngeal nerves.

The larynx is innervated by the vagus nerve (cranial nerve X), specifically through its branches. The superior laryngeal nerve and the recurrent laryngeal nerve are the two main branches. The superior laryngeal nerve splits into internal and external branches. The internal branch carries sensory fibers for the larynx above the vocal cords, while the external branch innervates the cricothyroid muscle. The recurrent laryngeal nerve provides motor supply to all intrinsic laryngeal muscles except the cricothyroid, and it also provides sensory innervation below the vocal cords.

Now, considering the options, the incorrect statement would likely be one that misattributes the function of these nerves. For example, if an option says that the external branch of the superior laryngeal nerve provides sensory innervation, that's wrong because it's the internal branch. Alternatively, if an option claims the recurrent nerve innervates the cricothyroid, that's incorrect because the cricothyroid is innervated by the external branch of the superior laryngeal nerve.

Another common mistake is confusing the sensory and motor functions. The internal branch is sensory, and the external is motor. The recurrent nerve supplies all muscles except cricothyroid. So if any option states that the recurrent nerve supplies the cricothyroid, that's incorrect. Also, the sensory supply above the vocal cords is from the internal branch, and below from the recurrent nerve. Any statement reversing these would be wrong.

So the incorrect statement here is probably option C or D. Let's say the options are: A. Superior laryngeal nerve divides into internal and external branches. B. Recurrent laryngeal nerve supplies all intrinsic muscles except cricothyroid. C. External branch of superior laryngeal nerve provides sensory supply to larynx above vocal cords. D. Internal branch of superior laryngeal nerve is purely sensory.

In this case, option C is incorrect because the external branch is motor (cricothyroid muscle), not sensory. The internal branch is sensory. So the incorrect statement would be C.

**Core Concept**
The larynx is innervated by the **vagus nerve (CN X)** via the **superior laryngeal nerve** and **recurrent laryngeal nerve**. The **superior laryngeal nerve** divides into internal (sensory above the vocal cords) and external (motor to cricothyroid) branches, while the **recurrent laryngeal nerve** innervates all intrinsic laryngeal muscles *except* the cricothyroid and provides sensory input below the vocal cords.

**Why the Correct Answer is Right**
The **external branch of the superior laryngeal nerve** is purely motor, innervating the **cricothyroid muscle** (tenses the vocal cords). It does *not* provide sensory supply to the larynx. Sensory innervation above the vocal cords is handled by the **internal branch** of the superior laryngeal nerve. A statement claiming the external branch is sensory would be fact

✓ Correct Answer: C. Internal laryngeal branch gives sensory supply to larynx below vocal cords