Aphasia is a loss of language functions causes by insult to the language areas of the brain. The most common cause of such insult is a stroke, however a blow to the left side of the head can also lead to aphasia. Broca's aphasia results from a damage to Broca's area of the brain, associated closely with syntax and the grammatical functions of language. Broca's aphasics have some trouble accessing verbs but have far more trouble accessing grammatical morphemes and their ability to access nouns and adjectives remains relatively unaffected. The following is a transcript of an interview by a doctor with a patient suffering from Broca's aphasia. Notice that the patient has little trouble expressing nouns, adjectives, and even verbs in this case; however, grammatical functors like the, a and pronouns are totally absent.
Cinderella...poor...um 'dopted her...scrubbed floor, um, tidy...poor, um...'dopted...Si-sisters and mother . . . ball. Ball, prince um, shoe . . .
Examiner Keep going. M.E.
Scrubbed and uh washed and un...tidy, uh, sisters and mother, prince, no, prince, yes. Cinderella hooked prince. (Laughs.) Um, um, shoes, um, twelve o'clock ball /pnat/, finished.
Examiner So what happened in the end? M.E. Married. Examiner How does he find her? M.E.
Um, Prince, um, happen to, um...Prince, and Cinderalla meet, um met um met.
What happened at the ball? They didn't get married at the ball.
M.E. No, um, no...I don't know. Shoe, um found shoe...

Wernicke's aphasia results from damage to Wernicke's area of the left hemisphere of the brain. Wernicke's aphasics have more difficulty accessing lexemes, nouns, verbs, and adjectives. Here is an example of the speech of a Wernicke's aphasic.
Uh, well this is the ... the /dd/ of this. This and this and this and this. These things going in there like that. This is /sen/ things here. This one here, these two things here. And the other one here, back in this one, this one /g?/ look at this one.
Examiner Yeah, what's happening there? C.B.
I can't tell you what that is, but I know what it is, but I don't now where it is. But I don't know what's under. I know it's you couldn't say it's ... I couldn't say what it is. I couldn't say what that is. This shu-- that should be right in here. That's /bli/ bad in there. Anyway, this one here, and that, and that's it. This is the getting in here and that's the getting around here, and that, and that's it. This is getting in here and that's the getting around here, this one and one with this one. And this one, and that's it, isn't it? I don't know what else you'd want.
Notice that this speech is filled with pronouns, contractions, conjunctions, the but the speaker is having trouble accessing the general notions of lexemes.