Joseph, a man in his early 70s, was having problems chewing his f...

Question

Joseph, a man in his early 70s, was having problems chewing his food. He was asked to stick out his tongue. It deviated to the right, and its right side was quite wasted. What cranial nerve was impaired?

Accepted Answer

Welcome back. Everyone which of the following nerves can cause a deviation of the anterior two thirds of the tongue if the lateral or on the same side of the brain lesion, if damaged, we've got choice. A, the trigeminal nerve choice B, the glossopharyngeal nerve choice C the hypoglossal nerve or D the vagus nerve. Let's start by defining each of these nerves beginning with the trigeminal nerve. So we're going to distinguish the trigeminal nerve from its motor and sensory functions and recall that the trigeminal nerve is known as cranial nerve five or V. Beginning with an example of its motor functions. Recall that due to the trigeminal nerves, mandibular division allows for its responsibility of the mastication muscles known as the jaws, sorry the jars. And this is allowed for the responsibility of chewing as a motor movement. An example of the sensory functions of the trigeminal nerve covers the other two divisions, which would be the ophthalmic and men and maxillary division, which in total covers the face, mouth and anterior two thirds of the tongue where there is no taste. However, the sensory functions would include touch, temperature, pain, and proprioception. Now, second, we're going to cover the glossopharyngeal nerve and again, break it down into its motor and sensory functions. Recall that the glossopharyngeal nerve is considered cranial nerve IX or nine. Because the glossopharyngeal nerve extends into the neck and throat. Its motor branch will cover the phal muscles which are responsible for contraction. And that is useful in the process of swallowing. Now, as a part of the glossopharyngeal nerves, sensory functions that would include taste with regard to the posterior third portion of the tongue, also known as the base of the tongue. And again, because the glossopharyngeal nerve extends into the neck where the carotid artery is present. There are then carted bodies which contribute to the sensory function to sense changes in blood pressure and blood gas levels. Now, the glossopharyngeal nerve does not pretty much directly relate to the tongue. So will roll choice be out and that will make room to cover the next nerve, which is the hypoglossal nerve. So we've got the hypoglossal nerve and recall that this nerve is considered cranial nerve. Number 13 xi I. So breaking down its motor and sensory functions, beginning with the motor functions recall that it's responsible for the intrinsic and extrinsic tongue muscle movement. So overall, it provides voluntary motor control of tongue movements and then with regard to the sensory functions of the hypoglossal nerve, there are only few sensory fibers present. And so the hypoglossal nerve is mainly identified by its motor functions. So we'll highlight m for the hypoglossal nerve since it's mainly identified by its motor functions of the tongue and its muscle movement. And so fourth, we then have the vagus nerve and we will recognize the vagus nerve as cranial nerve. Number five or X, breaking down its motor versus sensory sensory functions. Recall that the vagus nerve is a very large and mixed nerve which covers the muscles of the pharynx, larynx and soft palate, which are tied to the functions of speech and swallowing. And as far as the sensory functions of the vagus nerve, it will include taste as well as sensing any changes in the internal environment, which is tied to another motor function. We can note for the vagus nerve since it also innervates visceral organs like the lungs, heart and bronchi, we're going to include parasympathetic functions as well, which as far as motor functions will help do things like slow heart rate, stimulate digestion or promote relaxation and et cetera. So overall, the vagus nerves contribution to tongue movement is more so minimal. And we're going to rule out choice d the vagus nerve, we're also going to rule out the trigeminal nerve in choice. A since its function related to the tongue is more so sensory. And so as far as the motor movement of the tongue being affected, we would reference choice c the hypo fossil nerve as the main and correct choice. Since it's directly involved in the intrinsic and extrinsic tongue muscle movement. And so any damage done to the anterior two thirds of the tongue can lead to tongue paralysis. And so our final answer is again, see the hypoglossal nerve where any damage to this nerve can cause a deviation of the anterior two thirds of the tongue ipsilateral to the brain lesion. I hope that this made sense and let us know if you have any questions.

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Joseph, a man in his early 70s, was having problems chewing his food. He was asked to stick out his tongue. It deviated to the right, and its right side was quite wasted. What cranial nerve was impaired?

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