What was the critical analysis about language and brain determined by Broca (1861) and Wernicke (1874)?

Broca and Wernicke determined brain regions associated with language. In 1861, Broca, a French neurosurgeon, examined the brain of a deceased man who understood language but could not produce it. This man, nicknamed Tan, had a lesion in the interior part of the left frontal cortex of his brain. Broca identified the left side of the brain as the hemisphere that produces language. This region of the frontal cortex became known as "Broca's area" and was the first part of the brain to be determined to play a specific function.

In 1874, Wernicke, a neurologist, found an area in the posterior part of the left temporal lobe of the brain that is involved with comprehending language. People with a lesion in this area could speak, but their language was incomprehensible. Brain scientists now know that around the lateral sulcus in the left hemisphere of the brain, there are areas that are necessary for producing and understanding language. The front part of this region is known as Broca's area, which is necessary to produce language, while Wernicke's area, which is necessary for processing language, is in the posterior temporal lobe. This so-called "language loop" is found in the left hemisphere of the brain in 90% of right-handed people and 70% of left-handed people, and it is also found in this hemisphere among people who use sign language.