Good morning this is Dr. Adel Bandock professor of anatomy and neuroscience Mansoura University Egypt today I will talk about the neuro anatomical basis of three disorders of the higher brain function namely aphasia, agnosia and apraxia but first reminding you of the four language areas the four language areas are one motor and the three sensory These language areas are present in the dominant hemisphere. and the dominant hemisphere is the left hemisphere in 95 percent of the right-handed persons and is also is the left hemisphere in about 85 percent of the left-handed persons the four languages the four language areas are okay motor speech area and the motor speech area which is broken area area 44 and the order to 45 which is present in the posterior part of the inferior frontal gyrus and it is responsible for formulation of words the three sensory speech areas are area 22 area 39 and area 40 so vernicki's area 22 present in the posterior part of the superior temporal gyrus and it is responsible for understanding the spoken language second one Angular gyrus, area 39, which is present in angular gyrus, and it is responsible for understanding the written language. The third one is area 40, which is present in the supramarginal gyrus, and it is responsible for understanding sizes, shapes, texture, and recognition of the body parts and left side from the right side. The sensory speech areas are connected with the motor speech area by the arcuate fasciculus.
okay it's called also called superior longitudinal fasciculus start by aphasia what is aphasia aphasia is in is language disability that causes four main problems the first problem is difficulty understanding second one difficulty speaking difficulty reading and difficulty writing so aphasia is language disorder that causes four problems difficulty understanding difficulty speaking difficulty reading and difficulty writing so what are the types of aphasia and the site of the lesion the types brookas aphasia or expressive aphasia Vernicose aphasia or sensory aphasia, global or total aphasia, conduction aphasia and the anomic aphasia. The site of the lesion of Broca's aphasia is Broca's area. In Wernicke's aphasia, the site of the lesion is Wernicke's area, and global aphasia is a lesion in both Broca's and Wernicke's area. Conduction aphasia is a lesion in the arcuate fasciculus, which connects Broca's area with Wernicke's area, and anomic aphasia is a lesion in the angular diarhus.
Now let us describe each one. Broca's aphasia, Wernicke's aphasia and global aphasia. Broca's aphasia, the lesion is in Broca's area. The words are difficult to come with inability to speak.
but comprehension is normal because Wernicke's area is intact and the patient has the ability to write the patient can point at objects Broca's aphasia is also called expressive aphasia motor aphasia or non-fluent aphasia in Wernicke's aphasia The site of the lesion is Wernicke's area 22. The patient doesn't understand and doesn't comprehend spoken and written language. The patient speaks fluently because Broca's area is intact, but what they say is meaningless. It is also called sensory aphasia, receptive aphasia, and effluent aphasia.
In global aphasia, the lesion, it is total damage of vernacular area and bronchial area and arcuate fasciculus. And here, the patients cannot read, write, repeat sentences, or name objects. And then conduction aphasia.
In conduction aphasia, the lesion is in arcuate fasciculus, which connects Broca's area with Wernicke's area. Comprehension is normal because Wernicke's area is intact, but the patient, but the speech is fluent and meaningless because Broca's area is disconnected from Wernicke's area. In anomic aphasia, The lesion is limited to angular gyrus and it is manifested by Alexia and Agraphia.
Alexia is an inability to read, Agraphia is an inability to write. Then, Agnosia. Agnosia is an ability to recognize a sensory modality, although the sense is intact, such as auditory, visual, or tactile agnosia. Example, patient with auditory agnosia hears the doorbell ring, but he doesn't recognize its meaning. So, we have auditory agnosia, visual agnosia, and visual agnosia.
tactile agnosia and prosopagnosia okay auditory agnosia auditory agnosia it is inability to recognize familiar sounds although hearing is normal and the lesion is in Wernicke's area of the dominant hemisphere in tactile agnosia or asteriognosis it is inability to recognize objects by the sense of touch, with eyes closed, although touch sensation is intact. The lesion is in the somatosensory association area, area 5, 7, and 40. And then visual agnosia. Visual agnosia is inability to recognize what we see, although vision is normal.
All what is being seen is meaningless. and the site of the lesion is in the visual association area 18 and 19 and we have also color agnosia color agnosia is absence of color vision then prosopagnosia or face blindness in prosopagnosia it is inability to recognize familiar faces like the face of the father mother and sister They rely on sounds for proper recognition. And the site of the lesion is in the posterior part of the fusiform gyrus. It is in area 37. So prosopagnosia, or face blindness, is inability to recognize familiar faces. And the site of the lesion is area 37, which is located in the posterior part of the fusiform gyrus.
we have also what is called unilateral neglect and finger agnosia this is a normal view and this is left side neglect unilateral neglect and finger agnosia it is usually left side neglect usually left aside The left part of the space doesn't exist. Why? Because the left space is processed only by the right hemisphere.
On the other hand, the right space is processed by the two hemispheres. Therefore, lesion in the right hemisphere will lead to left side neglect. Amen. may only shave the right side of his face and ignore the left side.
A woman may only apply makeup to her right side. The lesion, the site of the lesion is in the right supramarginal gyrus. Of the right supramarginal gyrus. Okay? So it is usually in the non-dominant hemisphere.
Then a fraction. Apraxia is motor disorder. This motor disorder causes inability to perform learned or familiar movement on command, although there is no paralysis.
A person with apraxia may be unable to tie their shoes or open a door on command. Apraxia is due to lesion in the dominant hemisphere. Typically in the premotor area 6, inferior parietal lobule or in the corpus callosum. So we have motor apraxia, tallusal apraxia, and constructional apraxia.
So I will describe three types, motor, callosal, and constructional. Motor apraxia. Motor apraxia is an inability to plan or perform any motor activity upon oral command, although it is perfectly done spontaneously.
The patient cannot open a door upon command, but can perform the action spontaneously without thinking. The site of the lesion is in the premotor area 6. inferior parietal lobule or arcuate fasciculus of the dominant hemisphere. So motor apraxia is due to lesion in the premotor area 6, inferior parietal lobule or arcuate fasciculus of the dominant hemisphere.
Collosal apraxia. collosal apraxia is called split brain or collusal disconnection syndrome this is a corpus collosum okay corpus collosum this corpus collosum is formed of commissural fibers which connect the dominant hemisphere with the non-dominant hemisphere it is formed of four parts rostrum genoa body and dysplenium This corpus callosum transfers information from the dominant to the non-dominant hemisphere. This information is mainly memory and language.
The corpus callosum is supplied mainly by the anterior cerebral artery. However, the rostrum may receive branches from the anterior communicative artery. The spleenium may receive a branch from the posterior cerebral artery.
Callusal apraxia is due to total disconnection of corpus callosum and this it is confined to the left hand it is usually due to ischemic infarction of corpus callosum so callusal apraxia is due to infarction acute infarction of the corpus callosum disconnecting the dominant hemisphere from the non-dominant hemisphere Then, constructional apraxia. Constructional apraxia is inability to draw shapes like circles or squares and to design or copy a simple diagram like this. This is a copy of the patient drawings. Constructional apraxia. It is due to a lesion in the inferior parietal labule of the non-dominant hemisphere.
Lesion in the non-dominant hemisphere, in the inferior parietal labule of the non-dominant hemisphere. And thank you very much, best wishes and good luck.