Control of speech

Mechanism of Control of speech

1. MECHANISM & CONTROL OF SPEECH Fatima Wahid Mangrio [email protected]

2. SPEECH Speech is defined as the expression of thoughts by production of articulate sound, bearing a definite meaning . It is one of the highest functions of brain. When a sound is produced verbally, it is called the speech. If it is expressed by visual symbols, it is known as writing. If visual symbols or written words are expressed verbally, that becomes reading.

3. MECHANISM OF SPEECH Speech depends upon coordinated activities of central speech apparatus and peripheral speech apparatus. Central speech apparatus consists of higher centers, i.e . the cortical and subcortical centers. Peripheral speech apparatus includes larynx or sound box, pharynx , mouth, nasal cavities, tongue and lips. All the structures of peripheral speech apparatus function in coordination with respiratory system, with the influences of motor impulses from respective motor areas of the cerebral cortex.

4. NERVOUS CONTROL OF SPEECH Broca’s speech area (areas 44 and 45) is located in the frontal lobe. Speaking and understanding language are complex activities that involve several sensory, association, and motor areas of the cortex. In about 97% of the population, these language areas are localized in the left hemisphere.

5. The planning and production of speech occur in the left frontal lobe in most people. From Broca’s speech area, nerve impulses pass to the premotor regions that control the muscles of the larynx, pharynx, and mouth. The impulses from the premotor area result in specific, coordinated muscle contractions.

6. Simultaneously, impulses propagate from Broca’s speech area to the primary motor area. From here, impulses also control the breathing muscles to regulate the proper flow of air past the vocal cords. The coordinated contractions of your speech and breathing muscles enable you to speak your thoughts.

7. NONFLUENT APHASIA People who suffer a cerebrovascular accident (CVA) or stroke in this area can still have clear thoughts but are unable to form words, a phenomenon referred to as nonfluent aphasia.

8. WERNICKE’S AREA Wernicke’s area (area 22, and possibly areas 39 and 40), a broad region in the left temporal and parietal lobes, interprets the meaning of speech by recognizing spoken words. It is active as you translate words into thoughts. The regions in the right hemisphere that correspond to Broca’s and Wernicke’s areas in the left hemisphere also contribute to verbal communication by adding emotional content, such as anger or joy, to spoken words .

9. Fluent aphasia Unlike those who have CVAs in Broca’s area, people who suffer strokes in Wernicke’s area can still speak, but cannot arrange words in a coherent fashion (fluent aphasia).