Wernicke's aphasia is named after Carl Wernicke who described a type of aphasic disorder, different than Broca's aphasia, related to the left posterior part of the first temporal gyrus in 1874. Wernicke described the disorder as an amnesiac disorder characterized by fluent but disordered speech, with a similar disorder in writing, and impaired understanding of oral speech and reading. He called this disorder sensory aphasia, which became known as Wernicke's aphasia.
Wernicke’s aphasia is known
as a fluent aphasia because the patient does not appear to have
any difficulty articulating speech, but may be paraphasic.
However, comprehension of speech is impaired and sometimes as
much as single words are not comprehended. The patient may even
speak in meaningless jargon, known as neoligistic jargon, devoid
of any content but free use of verb tenses, clauses, and
subordinates. Here is a CT scan of a patient who suffered from Wernicke's aphasia. It comes from the Whole Brain Atlas at Harvard University Medical School. The patient's left is on the right. As you can see, the lesion is in the parietal lobe and appears to include a large portion of the perisylvian region.