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.
6. • 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.
7. • 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.
8. 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.
9. 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.
10. 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).
