Final answer:
The left side of the tongue will atrophy if there is hypoglossal nerve injury on the left side. The tongue protrusion test, where the deviation of the tongue indicates the side of injury, is a useful diagnostic tool. Atrophy occurs due to the lack of proper nerve signals leading to muscle weakness.
Step-by-step explanation:
If a student has a hypoglossal nerve injury on the left side, it is the left side of the tongue that will atrophy. The hypoglossal nerve innervates the muscles of the tongue, and it is crucial for movements including protrusion, retraction, and elevation. When there is an injury to this nerve on one side, the muscle on the affected side will not receive the proper signals, leading to weakness and eventually atrophy over time. The genioglossus muscle, which is mainly responsible for protruding the tongue, will push the tongue towards the side of the nerve deficit when attempting to stick it out. Therefore, if a patient cannot stick their tongue out straight, and it deviates to one side, this is indicative of damage on that same side.
An injury to the left hypoglossal nerve would result in the tongue deviating to the left when a patient tries to stick it out, suggesting that damage is on the left side. Consequently, atrophy would occur on the left side where the nerve is impaired. Not only does this affect tongue movement, but it can also have implications on speech and swallowing functions. A thorough examination by a healthcare professional is necessary to properly assess the extent of nerve damage and initiate appropriate treatment.