This document outlines the functional areas of the cerebral cortex, as presented by Dr. Muhammad Ali Rabbani. It discusses the primary motor, sensory, visual, auditory, and association areas located within the frontal, parietal, occipital and temporal lobes. For each area, the document describes its Brodmann area number, location within the lobe, histology, functions, what symptoms result from lesions, and how it relates to other areas. The overall purpose is to educate participants on the organization and functions of the different cortical regions involved in movement, sensation, perception and higher-level processing.
Call Girls Coimbatore Just Call 9907093804 Top Class Call Girl Service Available
Cerebral Cortex - Functional Areas.pdf
1. info@medicoseacademics.com
0310-7990649
Cerebral Cortex – Functional Areas
Dr. Muhammad Ali Rabbani
Asst. Professor Anatomy
MBBS (NMC, Multan)
FCPS (Anatomy)
CHPE (Certificate in Health Professional Education)
DHPE (Diploma in Health Professional Education)
MBA (Masters of Business Administration)
MPH (Masters of Public Health)
2. info@medicoseacademics.com
0310-7990649
Learning Objectives
By the end of this lecture participants should be able to
• Enumerate the cortical areas in frontal, parietal, occipital & temporal
lobes
• Elaborate the functions of each of the cortical area
• Correlate the lesions of different areas with the symptoms produced
• Differentiate between the primary and association areas
• Elaborate the concept of cerebral asymmetry
Dr Muhammad Ali Rabbani 2
5. info@medicoseacademics.com
0310-7990649
Precentral Area
• Location
• Anterior wall of Central Sulcus
• Precentral Gyrus
• Posterior parts of horizontal gyri
• Histology
• Absence of Granular Layers
• Prominence of large Pyramidal Cells
• Giant Pyramidal Cells of Betz
Most in Primary Motor Cortex
Dr Muhammad Ali Rabbani 5
6. info@medicoseacademics.com
0310-7990649
Primary Motor Area (MI)
• Brodmann Area 4
• Location
• Anterior Wall of Central Sulcus
• Precentral Gyrus
• Anterior part Paracentral Lobule
• Giant Cells of Betz in Layer V
Dr Muhammad Ali Rabbani 6
7. info@medicoseacademics.com
0310-7990649
Primary Motor Area (MI)
• Function
• “Final Station for conversion of design into execution”
• Origin to Corticospinal/bulbar tracts
• Discrete Isolated movements contralateral side
• Bilateral movements
• extraocular muscles, upper face, tongue,
mandible, pharynx, larynx
• No ipsilateral movement
Dr Muhammad Ali Rabbani 7
8. info@medicoseacademics.com
0310-7990649
Primary Motor Area (MI)
• Motor Homunculus
• Somatotrophic Representation of the Body
• Location may vary but sequence seems constant
• Discuss locations and disproportionate representations
• Relate with arterial supply
Dr Muhammad Ali Rabbani 8
10. info@medicoseacademics.com
0310-7990649
Primary Motor Area (MI)
• Lesion
• Contralateral Upper Motor Neuron Lesion
• Greatest in the distant musculature
• Bilateral Lesion of paracentral lobule →
urinary incontinence
• Pure lesion rarely results in muscle spasm
• Jacksonian Epileptic Seizures – irritative
lesion
Dr Muhammad Ali Rabbani 10
11. info@medicoseacademics.com
0310-7990649
Premotor / Secondary Motor Area
• Brodmann Area 6, (8, 44, 45)
• Location
• Anterior part Precentral Gyrus
• Posterior parts of Horizontal Gyri
• No Giant Cells of Betz
• Connected to main sensory cortex (SI)
• Function
• ‘Store programs of motor activity assembled as
the result of past experience’
• Programming of intended movements and
control of movements in progress
• Coarse Postural movements
• Control of proximal and axial muscles
Dr Muhammad Ali Rabbani 11
12. info@medicoseacademics.com
0310-7990649
Premotor / Secondary Motor Area
• Damage causes apraxia
• a disruption of the patterning and execution of learned/skilled motor
movements
• there is no weakness
• but the patient is unable to perform movements in the correct sequence
• Sympathetic Apraxia: motor apraxia in non-dominant hand
• Combined lesion of Area 4 & 6 cause complete spastic palsy
12
Dr Muhammad Ali Rabbani
13. info@medicoseacademics.com
0310-7990649
Frontal Eye Field
• Brodmann’s Area 8
• Facial Area of Precentral Gyrus →
Middle Frontal Gyrus
• Function/Stimulation
• Conjugate movement to the opposite side
• Voluntary Scanning movements
independent of visual stimuli
• Lesion
• Conjugate deviation towards the lesion
• Involuntary Tracking remains intact
Dr Muhammad Ali Rabbani 13
14. info@medicoseacademics.com
0310-7990649
Motor Speech Area of Broca
• Brodmann’s Area 44, 45
• Inferior Frontal Gyrus
• Important on Dominant Hemisphere
• Ablation → paralysis of speech
• Formation of words by connections
with the adjacent primary motor areas
• Connected to Wernicke’s through
Arcuate Fasciculus
• Lesion discussed with speech
Dr Muhammad Ali Rabbani 14
15. info@medicoseacademics.com
0310-7990649
Prefrontal Cortex
• Brodmann Areas 9-12 (1/4th of the cortex)
• Reciprocal connections with dorsomedial nucleus of thalamus
• Anterior to the precentral Area
• Superior, middle, inferior, medial, orbital, cingulate gyri
• Functions
• organizing and planning the intellectual and emotional aspects of behavior
• Makeup of individual’s personality
• Regulator of depth of feeling
• Influences initiation and judgement
Dr Muhammad Ali Rabbani 15
17. info@medicoseacademics.com
0310-7990649
Prefrontal Cortex (Frontal Lobe)
• Frontal Lobe Syndrome (Phineas Gage Syndrome)
• Inappropriate social behaviour
• cannot concentrate and is easily distracted
• general lack of initiative, foresight, perspective, and adaptation
• apathy (i.e., severe emotional indifference)
• abulia, a slowing of intellectual faculties, slow speech
• emergence of infantile suckling or grasp reflexes that are suppressed in adults
• Gait apraxia, incontinence
• akinetic mutism (a coma-like state called coma vigil).
17
Dr Muhammad Ali Rabbani
19. info@medicoseacademics.com
0310-7990649
Primary Somesthetic Area (SI)
• Brodmann Area 3, 1, 2
• Location
• Postcentral Gyrus
• Posterior part of paracentral lobule
• Histology
• Granular Type
• Outer Layer of Billarger prominent
• Signals are received in layer IV
• Layer VI send axons to lower relay stations
• Provide feedback, modulate intensity
Dr Muhammad Ali Rabbani 19
20. info@medicoseacademics.com
0310-7990649
Primary Somesthetic Area (SI)
• Function
• Receives fibers from VPL, VPM nuclei of thalamus
• Sensory homunculus
• Inverted representation of the body
• Most from contralateral side
some from oral region to the same side
pharynx, larynx, and perineum to both sides
• Area size ∝ number of sensory receptors
• Connections to
• Lower sensory relay centers
• Motor and association areas
Dr Muhammad Ali Rabbani 20
21. info@medicoseacademics.com
0310-7990649
Primary Somesthetic Area (SI)
• Lesion
• Contralateral sensory disturbances
more severe in distal parts
• Crude thermal & tactile sensations return
• remains unable to judge degrees of warmth
• unable to localize tactile stimuli accurately
• unable to Judge weights of objects
• Loss of muscle tone
Dr Muhammad Ali Rabbani 21
23. info@medicoseacademics.com
0310-7990649
Somesthetic Association Area
• Brodmann Area 5, 7, 40
• Superior Parietal Lobule
• Receives from Areas 3, 1, 2, 19
• Integrate sensory modalities
Relates to past experience
Interpret
• Stereognosis
• Lesion
• Astereognosis
Dr Muhammad Ali Rabbani 23
24. info@medicoseacademics.com
0310-7990649
Somesthetic Association Area
• Lesions (esp. in dominant side)
• Apraxia - disruption of the patterning and execution of
learned motor movements (e.g., constructional apraxia)
usually bilateral
• Astereognosis - inability to recognize objects by touch
There is no loss of tactile or proprioceptive sensation; rather, it is the
integration of visual and somatosensory information that is impaired
due to loss of input to prefrontal cortex
usually contralateral
• Astatognosis
inability to recognize position of body part
24
Dr Muhammad Ali Rabbani
25. info@medicoseacademics.com
0310-7990649
Asomatognosia
• Lesions in areas 7, 39, and 40
in the nondominant right parietal lobe
• Result in
• unawareness or neglect of the contralateral half of the body
ignore half of their body and may fail to dress, undress, or wash the affected
(left) side
• draw a clock face from memory, they will draw only the numbers on the right
• Although somatic sensation is intact
have no visual field deficits, but deny the existence of things in left visual field
26
Dr Muhammad Ali Rabbani
27. info@medicoseacademics.com
0310-7990649
Primary Visual Area
• Brodmann Area 7
• Walls of posterior part of calcarine sulcus
• Extends around the occipital pole
• Striate cortex, only a few pyramidal cells
• Receives optic radiations
• Area for macula
• At the posterior end
• Represents 1/3rd of occipital lobe
Dr Muhammad Ali Rabbani 28
28. info@medicoseacademics.com
0310-7990649
Primary Visual Cortex
• Damage to a discrete part of area 17 will produce a scotoma
(mapping)
• A unilateral lesion inside area 17 results in a contralateral
homonymous hemianopsia with macular sparing (PCA)
• Area serving the macula is represented in the most posterior part of
the occipital lobe
• Blows to the back of the head or a blockage in occipital branches of
the MCA that supply this area may produce loss of macular
representation of the visual fields.
29
Dr Muhammad Ali Rabbani
30. info@medicoseacademics.com
0310-7990649
Secondary Visual Area
• Throughout occipital lobe and posterior parts of parietal and temporal
• integrate complex visual input
• form and color, versus motion, depth and spatial information
• Lesion of area 20, 21 (information from cones stream and Blob zones)
• Achromatopsia - complete loss of color vision in the contralateral hemifields
• Prosopagnosia – an inability to recognize faces
read and name objects, can identify the person by sound
• Lesion of areas 18, 19 (from rod stream and Stripe zones)
• deficit in perceiving visual motion and depth
• visual fields, color vision, and reading are unaffected
31
Dr Muhammad Ali Rabbani
31. info@medicoseacademics.com
0310-7990649
Occipital Eye Field
• Exists in secondary visual area
• Conjugate deviation towards opposite side
• Reflexive, like when following an object
• Both hemispheres are connected to each other
Dr Muhammad Ali Rabbani 33
32. info@medicoseacademics.com
0310-7990649
Gerstmann Syndrome
• Lesion confined angular gyrus (area 39)
• Alexia - loss of ability to comprehend written language
• Agraphia - loss of ability to write it
• Spoken language may be understood
• Acalculia (loss of the ability to perform simple arithmetic problems)
• Finger agnosia (inability to recognize one’s fingers)
• Right– left disorientation
• Underlying optic radiation (retro-lenticular part of internal capsule) may get
involved
34
Dr Muhammad Ali Rabbani
35. info@medicoseacademics.com
0310-7990649
Primary Auditory Area
• Brodmann Area 41, 42
• Includes Gyrus of Heschl, inferior wall lateral sulcus
• Receives auditory radiations from medial geniculate body
• Tonotopic Organization
• Anterior - Low Frequency
• Posterior- High Frequency
• Lesion
• Partial Deafness in both, more in contralateral
• Difficulty in localization of sound
Dr Muhammad Ali Rabbani 37
36. info@medicoseacademics.com
0310-7990649
Secondary Auditory Area/
Auditory Association Cortex
• Location
• Posterior to Primary Auditory Area
• Superior Temporal Gyrus (Area 22)
• Receives from primary auditory area & thalamus
• Interpretation of sounds & association with other senses
Dr Muhammad Ali Rabbani 38
37. info@medicoseacademics.com
0310-7990649
Wernicke Area
• On dominant side
• Present in
• Superior Temporal Gyrus (22)
• Parietal Lobe (39, 40)
• Connected to Broca’s Area by Arcuate Fasciculus
• Receives fibers from visual & auditory cortex
• Permits the understanding of language (written or spoken)
39
Dr Muhammad Ali Rabbani
41. info@medicoseacademics.com
0310-7990649
Vestibular Area
• Location
• Postcentral Gyrus
Location of Face
• Opposite Auditory Area
• Functions
• Appreciation of position & movements of head in space
• Influences movements of eyes & muscles of trunks and limbs
Dr Muhammad Ali Rabbani 43
45. info@medicoseacademics.com
0310-7990649
Motor / Broca’s Aphasia
• Damage causes
• motor, non-fluent, expressive or anterior aphasia
• can understand written and spoken language but normally say almost
nothing
• The ability to write is usually also affected in a similar way (agraphia)
although the hand used for writing can be used normally in all other
tasks
• Sympathetic Apraxia
• Patients are keenly aware of and frustrated by an expressive aphasia
• May extend posteriorly to primary motor cortex (contralateral
paralysis of the muscles of the lower face, then upper limb if larger)
• Sympathetic Apraxia
47
Dr Muhammad Ali Rabbani
46. info@medicoseacademics.com
0310-7990649
Fluent / Receptive / Wernicke’s Aphasia
• Lesion in Wernicke’s Area
• cannot comprehend spoken language
• Alexia - not be able to read
• fluent verbalization but lacks meaning
• paraphasic, often misusing words as if speaking using a “word salad”
• Non-sequiturs, neologism, driveling speech
• unaware of their deficit and show no distress
• Often accompanied by Quadrianopia
• Lesion in nondominant → Sensory Dysprosody (Rhythm & pitch)
48
Dr Muhammad Ali Rabbani
47. info@medicoseacademics.com
0310-7990649
Conduction Aphasia
• Superior Longitudinal Fasciculus (or The Arcuate Fasciculus)
• large fiber bundle connecting Wernike with Broca area
• Lesion
• verbal and visual language comprehension are also normal
• Fluent aphasia - verbal output is fluent
• there are many paraphrases and word-finding pauses
• patient cannot repeat words or execute verbal commands by an examiner
• Nominal Aphasia - poor object naming
• aware of the deficit and are frustrated by their inability to execute a verbal
command that they fully understand
49
Dr Muhammad Ali Rabbani
51. info@medicoseacademics.com
0310-7990649
Language and Dominant Hemisphere
• Most people (about 80%) are right-handed
• This implies that the left side of the brain has more highly developed
• In most of these speech and language functions are also
predominantly organized in the left hemisphere
• By the definition of language & other centers 95% are left dominant
• Most left-handed people show language functions bilaterally,
although a few, with strong left-handed preferences, show right-sided
speech and language functions
54
Dr Muhammad Ali Rabbani
52. info@medicoseacademics.com
0310-7990649
Dominant Hemisphere
• Responsible for
• Language comprehension
• Speech and calculation
• Lesions
• Astereognosis
• Sensory Neglect
• Receptive aphasia
• Gerstmann syndrome
• Alexia with agraphia (often coexists with Gerstmann syndrome)
• Tactile agnosia
• Ideomotor apraxia
• Ideational apraxia
Dr Muhammad Ali Rabbani 55
53. info@medicoseacademics.com
0310-7990649
Non-Dominant Hemisphere
• Responsible for
• three-dimensional or spatial perception
• nonverbal ideation (music & poetry)
• Lesion
• Astereognosis
• Sensory Neglect
• Left sided hemineglect
• Anosognosia (denial of deficit)
• Topographic Apraxia
• Constructional Apraxia
• Dressing Apraxia
• Receptive & Expressive Dysprosody (pitch & rhythm)
Dr Muhammad Ali Rabbani 56
54. info@medicoseacademics.com
0310-7990649
Transcortical Apraxia
• Lesions to the corpus callosum (infarct of
ACA)
• There is no motor weakness
• the patient cannot execute a command to
move the left arm
• They understand the command, which is
perceived in the Wernicke area of the left
hemisphere, but the callosal lesion disconnects
the Wernicke area from the right primary
motor cortex so that the command cannot be
executed
• still able to execute a command to move the
right arm
57
Dr Muhammad Ali Rabbani
55. info@medicoseacademics.com
0310-7990649
Alexia Without Agraphia
• pure word blindness
• often have a color anomia
• disconnect syndrome in which
information from the occipital lobe is not
available to the parietal or frontal lobes
to either understand or express what has
been seen
• Due to left PCA which may also involve
• left occipital cortex
• splenium of the corpus callosum
58
Dr Muhammad Ali Rabbani
56. info@medicoseacademics.com
0310-7990649
Split Brain Syndrome
• Inability to match objects in two hands
• Inability to name objects in left hand
• Inability to match objects in two halves of visual field
• Alexia in left visual fields
Dr Muhammad Ali Rabbani 59