Final answer:
The two speech zones in the frontal cortex are Broca's area, which is involved in speech production and can lead to expressive aphasia when damaged, and Wernicke's area, which is crucial for language comprehension and associated with receptive aphasia upon damage.
Step-by-step explanation:
The human frontal cortex houses two essential speech zones responsible for language function known as Broca's area and Wernicke's area. Broca's area, found in the lateral aspect of the frontal lobe anterior to the motor cortex that controls head and neck movements, is essential for speech production. Individuals with damage to Broca's area can experience expressive aphasia, leading to non-fluent, halted, and grammatically poor speech. On the other hand, Wernicke's area, located near the end of the lateral sulcus adjacent to the auditory association cortex, is crucial for language comprehension. Damage here results in receptive aphasia, where individuals struggle to understand language both from others and themselves, even though they can still produce speech.
Moreover, these two areas are connected through the deep white matter running from the posterior temporal lobe to the frontal lobe, allowing for the integration of comprehension and speech production. The functionality of the speech zones is elucidated through their association with different types of aphasia, reflecting their specialized roles in language processing within the frontal cortex.