Language and speech physiology, Lecture notes of Physiology

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Physiology of Language and

Speech

Introduction

• (^) 1. Human beings are also capable of expressing their efficiency and emotions without using speech, like presenting oneself through the quality of work one does (the work language) or conveying the message through the physical changes (the body language) or through emotional feelings (the expressive language).
• (^) 2. Thus, language is not limited to the expression only through speech or writing.
• (^) 3. However, generally, it can be stated that language is the means of communicating one’s thought through spoken words or in writings, and is also the medium for all delicate interpersonal transactions.

Receptive areas

• (^) The receptive areas are also called sensory speech

areas as they receive and process the sensory

information for speech.

• (^) They are Wernicke’s area (area 22) that subserves

the perception of spoken language and the angular

gyrus (area 39) that subserves the perception

written language.

• (^) Area 41 and 42 also are included in receptive areas

that take part in processing spoken language.

Wernicke’s Area

• (^) The area is so named as it was described by Carl Wernicke in
• (^) 1. Wernicke’s area is located in the upper part of the temporal lobe.
• (^) 2. This is the major association area for processing sensory information from the somatic sensory, visual, and auditory cortices.
• (^) 3. Wernicke’s area is essential for the comprehension, recognition, and construction of words and language.
• (^) 4. Patients with lesion in Wernicke’s area may speak, but the words they frame and put together will have no meaning

Executive or Expressive Areas

• (^) The executive areas are also called motor speech areas as they execute the expression of speech. They are Broca’s area (area 44 and
  45. and Exner writing area.

Broca’s Area

• (^) Broca’s area is concerned with motor aspects of speech, hence called motor speech area (area 44 and 45). This area was described by Paul Broca in 1865.
• (^) 1. It is present in the frontal lobe.
• (^) 2. Broca’s area regulates functions of the muscles of the lips, tongue, pharynx and larynx.
• (^) 3. Patients with lesion of Broca’s area are capable of comprehending a spoken or written word but they are not able to say the word

Areas in the brain concerned with language and speech

Arcuate Fasciculus

• (^) The sensory and motor areas are intricately connected with each other. Especially, a rich network of nerve fiber, the arcuate fasciculus, which passes through the isthmus of temporal lobe and posterior end of the sylvian fissure, connects Wernicke’s area with Broca’s area.
• (^) This fasciculus coordinates the understanding and execution of speech and the language skills.
• (^) Broca’s area is further connected with lower rolandic cortex by short association fibers that in turn innervate the speech apparatus (muscles of mouth, tongue and throat).

• (^) For example, in Alzheimer’s disease gradual loss of all aspects of language function occurs without any specific aphasia.
• (^3). Dysarthria: Defect in articulation of speech with intact mental function and comprehension of spoken and written language. This occurs purely due to disorder of muscles of articulation, which may be due to flaccid or spastic paralysis. 4. Aphonia: Loss of voice due to disorder of larynx or its innervation.

Types of Aphasia

• (^) Broadly divided into Four categories:-
• (^) 1:- Motor Aphasia (Broca’s Aphasia)
• (^) This is also called nonfluent aphasia or expressive aphasia.
• (^) 1. This occurs in disease processes that affect Broca’s area.
• (^) 2. The primary deficit is in the language output or speech production. In its mildest form, motor speech deficit manifests as poverty of speech.
• (^) 3. In advanced form, there is complete loss of power of speaking.
• (^) 4. There is no paralysis of speech apparatus as patient can chew, swallow, clear the throat, cry or even vocalize without word.
• (^) 5. Usually, lower part of face, and arm of the right side are weak.

• (^) 3:- Global Aphasia
• (^) This occurs due to destruction of large part of language zones involving both Broca’s and Wernicke’s areas.
• (^) 1. The lesion usually occurs due to occlusion of the left internal carotid artery or middle cerebral artery.
• (^) 2. All aspects of speech and language are affected.
• (^) 3. At best they may say few simple words, but characteristically they fail to carry out a series of simple commands or name objects. They cannot read, write or repeat what is said to them.

• (^) 4:- Dissociative Language Syndromes
• (^) Dissociative language syndromes refer to language deficit that do not result from lesion of cortical language areas, but from disruption of pathways joining them.
• (^) Conduction Aphasia
• (^) Pure Word Deafness
• (^) Pure Word Blindness
• (^) Pure Word Mutism
• (^) Anomic Aphasia
• (^) Transcortical Aphasia

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