Dr.Mohammed Sadiq Azam

Postgraduate, Prof.Siraj’s unit, M:I

Deccan College of Medical Sciences

FUNCTIONAL ANATOMY OF

THE CEREBRAL HEMISPHERES

BRAIN - ANATOMY

BRAIN - ANATOMY

BRAIN - ANATOMY

BRAIN – FUNCTIONAL ANATOMY

HISTOLOGY

Six layers:

I: Molecular layer

II: External granular layer

III: Small pyramidal cell layer

IV: Internal granular layer

V: Large pyramidal cell layer

VI: Layer of fusiform or

polymorphic cells

SOMATOSENSORY CORTEX

SENSORY HOMUNCULOUS

• SSA 1 & SSA 2

• Amorphsynthesis – forgets one half

SOMATOSENSORY CORTEX

MOTOR CORTEX

MOTOR HOMUNCULOUS

MOTOR AREAS

• Way station for “command signals”

• Important in movement & equilibrium

• Reticular nuclei and vestibular nuclei

• Vestibular nuclei: M, K, S

ROLE OF BRAIN STEM IN MOTOR FUNCTION:

VISUAL CORTEX

VISUAL CORTEX

VISUAL CORTEX

CONTROL OF EYE MOVEMENTS

• EOM:• Medial & Lateral recti• Inferior & Suerior recti• Superior & Inferipr oblique

• MLF

CONTROL OF EYE MOVEMENTS

• Fixation eye movements

• Voluntary fixation mechanism

• Involuntary fixation mechanism

• Role of superior colliculi in involuntary fixation

• Continuous tremor

• Slow drift

• Flicking movts

• Saccadic eye movements

• Pursuit movements

AUDITORY CORTEX

AUDITORY CORTEX

• Determination of direction of entry of sound:

• Time lag between entry of sound into one ear and the other

• Difference between the intensities of the sounds in the two ears.

• Neural mechanism:

• Superior olivary nucleus

OLFACTORY CORTEX

• Very old – Medial olfactory area

• Hypothalamus & limbic cortex

• Less old olfactory area

• Limbic cortex & Paleocortex

• Newer pathway

• Dorsomedial thalamic nucleus

• Lateropasterior quadrant of the orbitofrontale cortex

ASSOCIATION AREAS

ASSOCIATION AREAS

• Parietooccipitotemporal association area:

• Spatial co-ordinates

• Language comprehension (Wernicke’s area)

• Visual comprehension (Angulate gyrus - Dyslexia)

• Naming objects

• Prefrontal association area:

• Sequential and parallel inputs of motor function

• Planning of motor activity (thought process)

• Working memory

ASSOCIATION AREAS

• = GENERAL INTERPRETIVE AREA

• = GNOSTIC AREA

• = KNOWING AREA

• = TERITARY ASSOCIATION AREA

• Single greatest role of any part of the cerebral cortex for the function of intelligence.

• Highly developed on the dominant hemisphere in the posterior part of the superior temporal lobe.

WERNICKE’S AREA:

• Most inferior portion of posterior parietal lobe.

• Visual comprehension

• Dyslexia

ANGULAR GYRUS

• Medial undersides of both occipital lobes

• Prosophenosia

FACE RECOGNITION

SPEAKING A HEARD WORD

SPEAKING A WRITTEN WORD

• Interpretation of music

• Nonverbal visual experiences (patterns)

• Spatial relationships between person and environment

• Body language, intonation of voices

• Somatic experiences from limbs and hands

NON DOMINANT HEMISPHERE

• Lesion at angular and supramarginal gyri near parietotemporal junction

• Dysgraphia

• Dyscalculia

• Finger agnosia

• Left right disorientation

Gerstmann syndrome

THANK YOU