Loss of tongue movement after head injury points to hypoglossal nerve damage.

Head injuries can shake up all kinds of functions, but sometimes the clearest clue sits right at the front of your mouth. If a client can’t move their tongue, the reason isn’t about mood or motivation—it’s a signal from a specific nerve. Let’s walk through why tongue movement points to one likely culprit and what that means for care.

Meet the tongue’s boss: the hypoglossal nerve

Here’s the thing about the tongue: it’s a muscular organ that keeps us talking, chewing, and swallowing with confidence. The nerve that really runs the show for tongue movement is the hypoglossal nerve, CN XII. It’s the motor highway to virtually all the intrinsic and extrinsic tongue muscles. When CN XII is intact, the tongue can protrude, retract, move side to side, and help shape sounds as we speak.

Why that matters after head trauma

In a client who has had a head injury, losing tongue movement isn’t random. It often means one thing: the hypoglossal nerve or its nucleus has been damaged. When CN XII is compromised, you’ll see practical, everyday consequences. Speech can become slurred or indistinct, swallowing can feel awkward or unsafe, and articulating phrases—especially those that require precise tongue movements—can be noticeably impaired. It’s not just a motor story; it’s a signal about how the person will eat, drink, and stay comfortable during meals.

How to distinguish CN XII injury from other cranial nerves

You don’t want to second-guess in a clinical setting. Here’s a helpful quick-matcher:

• The facial nerve (CN VII): This nerve mainly controls muscles of facial expression. It creates a smile or a frown and helps with some eyelid and mouth movements, but it isn’t the primary driver of tongue movement.

• The trigeminal nerve (CN V): Think sensation and chewing—jaw clenching, bite strength, and facial sensation. It sets the stage for chewing, but it isn’t the main actor when you ask someone to stick out their tongue.

• The glossopharyngeal nerve (CN IX): This nerve touches taste and the throat’s swallow mechanics. It’s important for swallowing safety and taste, but it doesn’t commandeer tongue movements the way CN XII does.

When tongue movement is impaired, the most probable cause is damage to the hypoglossal nerve. Other nerves may influence swallowing in related ways, but the direct control of tongue motion points to CN XII.

A practical way to test in daily care

In a calm, careful exam, you can observe a few telltale signs:

• Ask the person to protrude the tongue. If the tongue deviates toward one side, that side’s hypoglossal nerve may be affected.

• Look for symmetry when the person sticks out their tongue straight ahead. Any weakness or tremor can hint at CN XII involvement.

• Note atrophy (shrinkage) or fasciculations (twitches) along the tongue muscles, which also support nerve involvement.

• Listen to speech quality. Slurred or oddly articulated speech can accompany tongue weakness.

• Watch swallowing. If you notice drooling, coughing during meals, or a prolonged swallow, those symptoms can be tied to tongue control issues.

What this means for patient care

When CN XII damage is suspected or known, care focuses on safety, function, and rehabilitation. Here are practical implications:

• Safety during meals: Tongue weakness can make swallowing less coordinated. Use swallowing precautions as needed—smaller bites, slower eating pace, upright positioning, and ensuring the patient is fully alert during meals.

• Speech and language support: Early involvement of a speech-language pathologist can make a big difference. They’ll guide tongue-strengthening exercises, articulation strategies, and compensatory techniques to improve communication.

• Oral care and hygiene: If tongue movement is limited, debris can linger more easily. Gentle oral hygiene becomes important to prevent irritation or infection.

• Respiratory vigilance: In some cases, swallowing impairment raises the risk of aspiration. Monitor for coughing, throat clearing, or changes in voice quality after swallowing, and act quickly if there are warning signs.

• Rehabilitative timing: Nerve injuries can recover, but the timeline varies. Consistent therapy and targeted exercises often yield the best outcomes. Patience and persistence matter.

A broader context: how nerves talk to the mouth and beyond

Tongue movement isn’t the whole story of speech, but it’s a big piece. The tongue works in concert with the lips, jaw, and soft palate to shape sounds. When one piece—like CN XII—falters, the whole orchestra can feel off. That’s why a head injury isn’t just “one problem.” It’s a cascade of interconnected functions: motor control, coordination, breathing, swallowing, and even taste in some cases.

Relating it to everyday life

Think about the tiny things you do without thinking—licking the lips after a salty bite, saying the “t” and “d” sounds clearly, or sipping from a straw. If the tongue can’t cooperate as it should, those everyday tasks start to feel unfamiliar. For patients, that can be frustrating or scary, especially when talk or mealtime becomes a hurdle. Recognizing the root cause—hypoglossal nerve damage—helps clinicians explain the situation honestly and map out a practical plan.

A quick note on prognosis and expectations

The brain and nerves are resilient, and some recovery is possible. The extent of recovery depends on the severity and location of the nerve injury, plus how promptly rehabilitation begins. Some patients regain substantial tongue function with therapy, while others may experience ongoing weakness or partial recovery. The key is a collaborative approach: medical teams, therapists, families, and the patient all aligned on goals and progress.

From theory to bedside: a concise takeaway

• If a client can’t move the tongue after head trauma, most likely CN XII damage.

• CN XII governs tongue protrusion, retraction, and lateral movements—critical for speech and swallowing.

• Other nerves (facial, trigeminal, glossopharyngeal) contribute to related functions but don’t control tongue movement in the same direct way.

• Practical assessments include tongue protrusion with observation of deviation, symmetry checks, and looking for atrophy or fasciculations.

• Care hinges on safety during meals, targeted therapy, and close monitoring of swallowing and speech needs.

• Recovery varies; early rehab and consistent therapy improve the odds of meaningful improvement.

A gentle closer: why this matters beyond the test

Knowledge like this isn’t just about answering questions correctly—it’s about understanding human function. When you can connect a symptom—like tongue movement loss—to a nerve’s job, you’re better prepared to troubleshoot with patients and families. You can explain what’s happening in language that makes sense, you can anticipate related challenges, and you can plan practical steps that actually help someone eat, speak, and feel more confident in daily life.

If you ever find yourself in a room with a patient who has tongue movement limitations after a head injury, remember the key idea: CN XII does the tongue’s heavy lifting. And when that nerve is disrupted, the ripple effects touch many parts of daily living. The good news is that with careful assessment, clear communication, and targeted rehabilitation, people can regain a surprising amount of function—and you’ll be there to guide them every step of the way.