cerebral cortex: its function lobes areas

1. Bismillahi rehman Al-raheem
NEUROLOGY
PRESENTATION ON
“CEREBRAL CORTEX’’

2. INTRODUCTION:
-It is a sheet of neural tissue that
surrounds the cerebrum of the
mammalian brain.
-It is completely made of grey matter
underlying white matter which consists
of axons communicating to and from
cortex.
-It has an area of 2.2 sqm in human
beings & about 2-4 mm thick.
-In large mammals, cerebral cortex is
usually folded, providing a greater
surface area without increasing the
size of brain.
-the ridge is termed as gyrus and the
groove is termed as sulcus.

3. -The cerebral cortex plays a key role in memory, attention, awareness,
thoughts, language and consciousness.
-It is divided into two cerebral hemispheres :left and right hemisphere.
-cerebral hemisphere, a part of brain controls muscle functions and
also controls speech, thoughts, emotions, writing, learning etc.
-the right side hemisphere controls muscles of left side of body & left
side hemisphere controls muscles of right side of body.
-It is subdivided into four lobes:
frontal lobe (motor control, thinking & reasoning)
parietal lobe (process sensory information)
temporal lobe (language, speech production, memory, emotion)
occipital lobe (main center for visual processing)

4. GREY MATTER:
-It is a major component of CNS, consisting neuronal cell bodies,
dendrites, unmylenated axons, oligodendrocytes & capillaries.
-It is the area from where the nerve impulse originates.
WHITE MATTER:
-It consists of largely nerve fibres.
-It’s main function is to transmit nerve impulses.
GYRI AND SULCUS:
-They are also known as hills and valleys of brain.
-The ridge is the gyrus while an depression is called sulcus.

5. -Gyrus & Sulcus serves two very imp
functions.
• They allow more neurons to be packed
into cortex and increases brain’s ability to
process information.
• they also form brain divisions by creating
boundaries between lobes of brain &
divides them into 2 hemispheres.
LAYERS OF CEREBRAL CORTEX:
-It is formed by six layers of structures from
outside (pial surface) to inside (white
matter).
1. molecular or plexiform layer.
2.external granular layer.
3.outer pyramidal layer.
4.internal granular layer.
5.ganglionic layer or internal pyramidal
layer.
6.fusiform cell layer.

6. 1.LAYER1:
-it contains few scattered neurons, axons and dendrites.
2.LAYER2:
-contains densely packed stellate cells, few small pyramidal cells.
3.LAYER3:
-Loosely packed stellate cells, inter-mediate sized pyramidal cells.
-this layer is the principle source of corticocortical efferents.
4.LAYER4:
-contains different types of stellate and pyramidal neurons.
-it is the main target of thalamocortical afferents from thalamus.

7. 5.LAYER5:
-contains large pyramidal neurons, gives rise to axons leaving cortex
and running down to subcortical str.(such as basal ganglia).
6.LAYER6:
-few large pyramidal neurons.
-this layer sends efferent fibres to thalamus
FUNCTIONAL/CORTICAL AREAS OF CEREBRAL CORTEX:-
There are three functional areas of cerebral cortex:
1.sensory areas.
2.motor areas.
3.associated areas.

8. 1. SENSORY AREAS:
-primary somatosensory cortex.
-somatosensory association cortex.
-visual & auditory areas
-others: olfactory, gustatory cortices.
1. primary somatosensory cortex:-
-It is located in post central gyrus,
found in parietal lobe.
-It consists of brodsmann’s area 3a,3b,
1&2.
-It is responsible for processing somatic
sensations.These sensations arises
from receptors throughout the body
responsible for detecting touch,
proprioception (perception of presence
of diff body parts), nociception (pain),&
temperature.

9. 2. somatosensory association cortex:-
-located posterior to primary somatosensory cortex.
-it integrates sensory information coming from primary somatosensory
cortex to produce an size, texture & relation of stimulus.
-it is associated with area 5 &7 .

10. 3.visual(striate)cortex:-
The visual cortex of the brain is a part of the cerebral cortex that
processes visual information.
-located on posterior tip of occipital lobe.
-receives visual information from retina.
-primary visual cortex V1 surrounds and extends into a deep sulcus
called the calcarine sulcus (deep sulcus that starts in the temporal
lobe and continues into the occipital lobe).
-It is associated with area 17.
-visual associated cortex (extra striate) surround primary visual
cortex & responsible for other visual tasks (color, form & movement).

12. • visual pathway has two streams:
-ventral stream(action-what, for identification):-
associated with object recognition & form
representation.
-dorsal (action-where or how to):- deals with object
location & its motion.

13. Auditory cortex:-
-The primary auditory cortex, located in between the two
others, is mainly composed of two areas named the
Brodmann areas 41,42.
- It is located in the temporal lobe, right above the ears.
- The function of the primary auditory cortex is to process
sound. It processes such information as pitch, volume and
the location of a sound.

14. -The auditory association area (42,22) is a part of the brain
that is found in Wernicke's area.
- It is responsible for processing acoustic (sound) signals that
the brain interprets as sounds, speech or music.
- Wernicke's area is part of the cerebral cortex, along with
Broca's area, from where the capacity for speech and written
language originate.
OTHERS SENSORY ASSOCIATED AREAS :-
Olfactory cortex:

15. -the primary olfactory cortex is a portion of the cerebral
cortex involved in olfaction(smelling).
-it is a small area of frontal lobe above the orbit & in medial
temporal lobe (piriform cortex, part of brain related to
sense of smell).
-brodmann’s area 27, 34.
Gustatory cortex: brodmann’s area- 43.
-it is responsible for perception of taste (taste sensation).
-it is found on both frontal & insular lobe (located deep in
brain under frontal, parietal & temporal lobes).
-for insular lobe, area 52.

16. MOTOR AREAS:-
-primary (somatic) motor
cortex.
-premotor cortex.
-broca’s area.
-frontal eye field.
1.primary motor cortex:
-brodmann’s area 4.
-it is a portion of cerebral
cortex situated in dorsal
portion of frontal lobe.
-it involves in balance, control
of voluntary movements.

17. 2. premotor cortex:
-it occupies part of B. Area 6.
-located ant. to primary motor cortex.
-responsible for performing voluntary motor
activities initiated by primary motor cortex.
-controls more complex movements.
-controls learned, repetitious motor skills.
-coordinate simultaneous or sequential actions.
3. Broca’s area:-
-it is one of the main areas of cerebral cortex,
responsible for producing language.

18. -located in forebrain division of brain.
-it controls motor functions involved speech
production.
-it occupies brodmann’s area 44 & 45.
4.frontal eye field:
-it is a region located in frontal cortex.
-it occupies specifically, BA 8.
-it plays an important in control of visual attention
& eye movements (especially conjugate
movements-opposite side).

20. OTHER ASSOCIATED AREAS:-
-prefrontal cortex.
-language cortex/areas.
-general(common) interpretation areas.
-visceral association area.
1.prefrontal cortex:
-it covers the front part of frontal lobe.
-it contains BA 8-14, 24-25, 32, 44-47.
-it is responsible for cognitive behaviour,
personality expression, decision making &
social behaviour.

21. 2.language areas:-
-it refers to both broca’s area & wernicke’s area.
-it refers to areas of brain responsible for speech
processing & production.
-Broca’s area is located in frontal lobe of left
hemisphere, functions linked to speech production.

22. -wernicke’s area is linked to
speech, involved in understanding
of written & spoken
language(language production).

23. 3.General interpretation areas:
-involves parts of temporal, parietal & occipital
lobes.
-found in one hemisphere, usually left.
-responsible for integrating incoming signals into
single thoughts.
-involves in processing spatial rltnship.
4.Visceral association areas:
-located in cortex of insula.
-responsible for perception of visceral
sensations(internal organs like bladder).

24. Thank you for your
attention..!!