Language is a unique part of human interaction controlled by your brain’s various speech centers, including the Wernicke’s and Broca’s area.

Over thousands of years, language has evolved, and the ability to communicate has expanded. There are more words today than ever before, with more being created by the hour!

All of this complexity and advancement in language can leave you wondering exactly how speech works. From the vibration in your throat to the movement of your lips, speech is a complex function controlled by several key parts of the brain.

Injury to any one of these areas can result in various changes in your overall speaking ability. Injuries can impair anything, from the way you understand words to the way you communicate them.

Anatomical image of the brain showing areas responsible for various speech functions.  Share on Pinterest
Medical illustration by Bailey Mariner

The largest part of your brain, called the cerebral cortex, is divided into two sides or hemispheres — the left and right. For most right-handed people, the left side does the majority of the work during speech. In most left-handed people, the language centers are located in the right hemisphere.

The major functions of speech which are controlled by the left hemisphere include:

  • comprehension: understanding the meaning of words and sentences
  • articulation: the pronunciation of words
  • fluency: the timing, tones, and patterns of speech

Language skills and functions are located in the dominant hemisphere, the side of the brain opposite the dominant hand. But both hemispheres are involved with regulating the motor function of speech and deciding how to communicate with others, including reading social cues.

Aside from the two cerebral hemispheres, the brain is also composed of the brainstem and cerebellum. The cerebellum plays an important supportive role in all movement-based or “motor” functions.

The cerebellum is located in the middle of the back of your head. It helps to coordinate muscle contractions of the mouth and face during speech, which is essential for maintaining “normal” speech fluency.

There are several different parts or lobes of the cerebrum that contribute to different speech functions. Your brain’s major speech centers are located in the temporal and parietal lobes on the dominant side. Additional contributions also come from the frontal lobe, toward the front of your head.

These different parts of the brain all work together to influence your ability to speak. The basic functions of speech that are controlled by these areas include:

  • planning
  • generation
  • processing
  • comprehension
  • execution (speaking)

Wernicke’s area

This is the name of a specific part of the brain responsible primarily for the comprehension of language. This means that it helps to make sure that what you want to say actually makes sense.

It does this partly by assigning meaning to words and partly by helping you string those words together. If your brain didn’t assign meaning to words, you’d end up making nonsensical sounds when you speak.

If it didn’t string meaningful words together, you’d end up with jumbled sentences.

Broca’s area

Located relatively close to Wernicke’s area, Broca’s area has a similar but still different role to play. It’s involved primarily in the generation of language fluency. Whereas Wernicke’s area deals with making sense of words, Broca’s area deals with forming sentences before you speak.

You can think of Broca’s area like a language planning center. It organizes the ideas that you want to express through language. It also plays a minor role in speech comprehension as well.

Motor cortex

Your brain’s motor cortex is an area that’s responsible for the planning and execution of muscle movements. This is important for the generation and execution of speech, according to a 2015 study.

The motor cortex controls the muscles that are involved in speech. These include your:

  • mouth
  • lips
  • tongue
  • vocal cords

When you want to say something out loud, the motor cortex works together with Wernicke and Broca’s area to formulate the plan and make it happen.

Injury to any area of the brain involved in speech can result in speech impairments. In the extreme, a total loss of speaking ability can occur. But the extent of the impairment depends on which area of the brain was affected and what type of injury occurred.

Having a stroke is a common brain injury that can result in various speech impairments. A stroke occurs when there’s a loss of blood flow to some area of the brain. Head trauma or brain tumors can also cause speech impairments.

Fluent aphasia

An injury affecting Wernicke’s area results in the inability to understand words and produce understandable speech.

If this is the only speech area affected, the ability to produce speech overall is preserved, but the sentences often contain nonsense words or words that don’t belong in the sentence. This is also called fluent aphasia.

Non-fluent aphasia

When only Broca’s area is affected, words and speech are still able to be understood, but there’s difficulty communicating fluently.

The result is understandable sentences that are usually shortened and communicated slowly with missing words, also called non-fluent aphasia.


If there’s been an injury to the cerebellum, one result can be dysarthria. This refers to difficulty speaking due to loss of muscle control in the face.

In dysarthria, there are usually difficulties with tongue and lip movements that make it difficult to speak and be understood.


Injuries to the motor cortex can result in a similar scenario as dysarthria. But the difficulty isn’t so much about muscle control as it’s about planning.

In apraxia, the result is difficulty coordinating the movements needed for speech. Speech comprehension and production are unaffected, but the words can come out wrong. For example, instead of “potato” you might say “topato.”

Apraxia can be caused by a stroke or trauma but is often diagnosed in early childhood and sometimes has an unknown cause.

The planning and production of speech is a complex function controlled by several parts of the brain that all work together. The end result is a fluent and understandable sentence that expresses your thoughts as you intended.

Various communication disorders and speech impairments may be caused by brain injury. If you experience a speech disorder, you may consider speaking with a healthcare professional. They may recommend speech therapy, medication, or a combination of both to help you.

If you’re ready to seek support but don’t know where to start, consider checking out Psych Central’s guide for mental health support.