3. Introduction
• Cerebral cortex is involved in different motor and sensory function. The cortex
area is about 2.2 square meter
• It has two cerebral hemisphere right and left
• The characteristic feature of cerebral cortex is Sulci and Gyri
• Sulci are the depression present on cerebral cortex
• Gyri are the elevations present on cerebral cortex
• The two cerebral hemisphere are separated by a deep vertical fissure
• These two halves separated fully at anterior and posterior and partially in the
middle part due to the presence of Corpus callosum which is a connecting fibers
of these two halves
• And each half of cerebral hemisphere divided into 4 lobes namely: Frontal lobe,
Parietal lobe, Temporal lobe, Occipital lobe
4. • The main fissures or sulci which separate these lobes are
• 1.Centaral sulcus: is in between frontal and parietal lobe
• 2.Parieto occipital sulcus: is in between parietal and occipital lobe
• 3. Lateral sulcus or sylvian fissure: is in between parietal and temporal lobe
• 4.Callosomarginal fissure: is in between temporal and limbic area of frontal lobe
5. • Brodmann area:
• Brodmann areas are the regions of cerebral cortex based on its
microscopic structures and organisation of cells
• Brodmann areas are 52 in number i.e from area no 1,2,3------to-area
no 52
6. • Frontal lobe:
• Frontal lobe is situated in between frontal pole and central sulcus inferiorly up to lateral
sulcus
• It occupies 1/3 rd of cerebral cortex
• It has pre central gyrus, superior, middle, inferior frontal gyrus
• Functionally this lobe divided into two parts namely
1. Prefrontal cortex
2. Precentral cortex
• Precentral cortex further divided in to 3 parts
1.Primary motor area
2.Premotor area
3.Supplementary motor area
7. Prefrontal cortex:
• It is also called Orbito frontal cortex
• It is situated anteriorly in between anterior pole and precenteral area
of frontal lobe
• It has lateral medial and inferior surfaces
• ▸ Areas present in pre frontal cortex are 9,10,11,12,13,14 on lateral
surface 23,24,29,32 areas on medial surface
• Inferior surface has Orbital gyri
8. Connections of Prefrontal cortex:
• Afferent connections
• Receives fibers mainly from
• Dorsomedial nucleus of thalamus
• Hypothalamus
• Corpus striatum
• Amygdala
• Mid brain
• Efferent connections
• Send fibers to
• Thalamus
• Hypothalamus
• Tegmentum
• Caudate nucleus
• Pons
• Temporal lobe
• Area 13 along with hippocampus send fibers to mammillary body via fornix this area related with Emotions
9. • Functions of Prefrontal cortex:
• This area is center for higher functions like Emotions, learning, memory,
social behaviour
• Short term memories stored
• Center for planned actions
• Center for intelligence
• Bilateral removal of these area leads to lack of mental alertness and lack of
intiation very little changes in memory judgement and intelligence
10.
11. • Precentral cortex:
• It is posterior part of frontal lobe
• It is situated anteriorly in between central sulcus and prefrontal cortex,
posterior portion of middle, superior and inferior frontal gyri
• It extend to medial surface also
• It is also called excito motor cortex
• Precentral cortex again divided into
• Primary motor area
• Pre motor area
• Supplementary motor area
12. • Primary motor area:
• This area present through out the area of pre central gyrus adjoining area of central sulcus
• Area no. 4 and 4s are present in it
• Connections of Primary motor area:
• Afferent connections
• Receives fibers from
• Dentate nucleus via red nucleus
• Thalamus
• Efferent connections
• Send fibers to
• Corticospinal tract to spinal cord of opposite side
• Frontopontine fibers to pontine nuclei of same side
• Corpus striatum
• Red nucleus
• Thalamus
• Subthalamus
• Reticular formation
• Association fibers to this area to other area of cortex
13. • Functions of Primary motor area:
• This area is involved in voluntary movements and speech
Area 4:
• Area situated just in front of central sulcus on pre central gyrus as a strip
• Area has broad end at superiorly
• Most of efferent fibers arised from primary motor area and these fibers involved in voluntary movements of opposite side on
stimulation
Area 4S:
• This is called suppressor area
• It is present in front of area no.4 on precentral gyrus
• It inhibited the movements created by the area no 4 so that it control exaggerated movements
• Lesion in this area leads to paralysis of contralateral side (opposite side of body)
• Lesion of this area both side leads to total paralysis
• Recovery is late while recovering upper limb recovered first than lower limbs
14.
15. Pre motor area:
• This area present anterior to primary motor area
• Area involved in postural movements of body sent efferent fibers to axial muscles of body
• Areas involved are 6,8,44 and 45
• Area 6:
• Area no 6 divided in to 6a and 6b on frontal gyri, infront of area no 4
• This area also send efferent fibers through corticospinal tract along with area 4
• Functions of Area 6:
• Coordinates the movements intiated by area 4,that is it involved in skilled movements to perform accurate
mvt
• Lesion of this area leads to loss of skilled movements opposite side
• Lesion along with area 4 leads to severe hemiplegia
16. Area 8:
• This area also called Frontal eye field
• Present anterior to the area no 6
• It is concerned with eye ball movements
• Send fibers to i.e efferent connection with Occulomotor nuclei of midbrain
• Receive fibers from i.e afferent connection with Thalamus and Occipital lobe
Functions of Area 8: this area involved in eye ball movements, open and closure of eyelids, dilatation of pupil and lacrimation of opposite side of eye
• lesion of this area leads to loss of eye ball movements but not effect eyelids and pupil
Area 44 and 45:
• It is also called as Broca's area
• It is a Motor area of speech
• Situated on inferior frontal gyrus of frontal lobe
Functions of Broca's area:
• area responsible for movements of tongue, lips, and larynx which area involved in speech
• lesion of this area leads to Motor aphasia or Broca's aphasia
• In this person has idea about his statement but he is unable to talk fluently
17. • Supplementary motor area:
• This area present medial surface of frontal lobe
• Exact function of this area not understood clearly
• It suggested that it is concerned with coordinate skilled movements
18. Homunculus arrangement of motor areas in cerebral cortex
• The muscles of various parts of body represent in motor area 4 from
medial to lateral surface
• The order of representation from medial to lateral cortex is
• Toes-->ankle-->knee-->hip-->trunk-->shoulder-->arm-->elbow-->wrist-
->hand-->fingers-->face
• From their respective are the efferent fibers send to respective
muscles of opposite side except face
• Face receives efferents from both side cortex
19.
20. Parietal lobe:
• This is situated in between frontal lobe, occipital lobe and temporal lobe
separated by Central sulcus, parieto occipital sulcus and sylvian fissure
respectively Parietal lobe divided into 3 areas
• Somesthetic area I
• Somesthetic area II
• Somesthetic association area
• Along with it has another area present namely sensory motor area
• Parietal lobe mainly involved in sensory functions
21. Somesthetic area l:
• It is also called Primary somesthetic area or Primary sensory area
• It is situated posterior to the central sulcus on post central gyrus and on paracentral lobule of medial side
Areas:
• It has three areas 3,1 and 2
• Anteriorly on post central gyrus has area 3 and posteriorly has area 1 and 2
Connections:
• It receives afferent fibers from Thalamus as thalamic radiation
Functions of Somesthetic area I :
• It receives sensory impulses like pain, touch, temperature, pressure and proprioception from opposite side
• Area 1 involved in sensory perception and area 2 and 3 in integration of sensory impulses ▸ These area send feedback to pre motor area
• Apart from this it has also involved in
• Spatial recognition: Tactile localization and two point discrimination
• Recognition of intensity of stimuli
• Recognition of similarities and difference between stimuli
• If lesion in this area without involvement of thalamus leads to loss of discrimination but patient able perceive the stimuli
• If lesion in this area along with thalamus leads to loss of sensations opposite side
22.
23. Somesthetic area II:
• It is situated on post central gyrus below the somesthtic area I some
part of this area present in sylvian fissure
Connections:
• It receives afferent fibers from Thalamus and somesthetic area
directly
• Exact role of this area not clear but it concerned with perception of
sensation
24. Somesthetic association area:
• It is situated posterior to post
central gyrus in front of visual
cortex and above auditory
cortex medial side
Areas:
• It has areas 5 and 7
Function:
• This area center for combined
sensation like Stereognosis
• Lesion of this area leads to
Astereognosis
25. Sensory motor area:
• Sensory area not limited to parietal lobe it extends in to motor area of
pre central gyrus
• Similarly motor area not limited to frontal lobe it extends In to
sensory area post central gyrus
• This combined area called as sensory motor area
• Timing and programming of skilled movements involved in
Corticocerebellum are stored in sensory motor area
26. • Homunculus arrangement of sensory areas in cerebral cortex
• The various parts of body represent in primary sensory area from
medial to lateral surface
• The order of representation from medial to lateral cortex is
Toes-->ankle-->knee-->hip-->trunk-->shoulder-->arm-->elbow-->wrist--
>hand-->fingers-- >face(eyelids-->nose-->cheek-->upper lip-->lower lip)
27.
28. • Temporal lobe:
• Temporal lobe is situated below the fronto parietal lobe
• Temporal includes 3 areas
• Primary auditory area
• Auditopsychic area
• Area for equilibrium
29. Primary auditory area:
• This area include area no 41,42
• 41’42 areas are present on anterior transverse gyrus and anterior part of
superiortemporal gyrus
Connections:
• This area receives afferent fibers from Medial geniculate body and Pulvinar
• Send efferent fibers to medial geniculate body, inferior colliculus of mid brain and
pulvinar
Functions of primary auditory area:
• primary auditory area involved in perception of auditory stimulus
• but interpretation of sound i.e analysis of speech source of sound is done with
the help of Auditopsychic area
30. Auditory psychic area:
• This area include area no 22
• This is also called wernick's area
• It is situated on superior temporal gyrus posterior to area no 41,42
• It is helpful in interpretation of sound
• It is a sensory area of speech
• Lesion of this area leads to Sensory aphasia or Wernick's aphasia
• In this patient able to talk clearly but not related
Area for equilibrium:
• It is situated posterior to superior temporal gyrus
• It is helpful maintainence of equilibrium
• Stimulation of this area leads to dizziness, swaying, falling and feeling of rotation of body
31.
32. Occipital lobe:
• It is posterior part of cerebral cortex
• Temporally include visual cortex
• Visual cortex includes
• Primary visual area----- area no.17
• Visual association area--area no. 18
• Occipital eye field----area no. 19
Connections:
• It receives afferent fibers from lateral geniculate body
• Send efferents to superior colliculus and lateral geniculate body
Functions of Visual cortex :
• Primary visual are involved in perception of visual impulses
• Visual association area involved in interpretation of visual impulses
• Occipital eye field concerned with movement of eyes
35. • On each side of the brain, these ganglia consist of the
• caudate nucleus, putamen, globus pallidus, substantia nigra, and
subthalamic nucleus.
• They are located mainly lateral to and surrounding the thalamus,
occupying a large portion of the interior regions of both cerebral
hemispheres.
36.
37.
38. • Two main circuits
• The Putamen Circuit: For executing learned patterns of movement.
• The Caudate Circuit: For Cognitive Control of Sequences of Motor Patterns.
• The term cognition means the thinking processes of the brain, using both
sensory input to the brain plus information already stored in memory.
• Most of our motor actions occur as a consequence of thoughts generated
in the mind, a process called cognitive control of motor activity.
• The caudate nucleus plays a major role in this cognitive control of motor
activity.
39.
40. Functions of basal ganglia
• Function in association with the corticospinal system to control complex patterns of motor
activity(cutting paper with scissors, hammering nails, shooting a basketball through a hoop,
passing a football, throwing a baseball etc.
• Cognitive control of motor activity e.g. if a person comes across a lion he will subconsciously plan
1) turning away from the lion, (2) beginning to run, and (3) even attempting to climb a tree
• To Change the Timing and to Scale the Intensity of Movements
• A lesions of the posterior parietal cortex produce an inability to accurately perceive objects
through normally functioning sensory mechanisms, a condition called agnosia. In case of lesion in
the right posterior parietal cortex,the patient's ability to copy the left side of the drawings is
severely impaired.
• Also, such a person will always try to avoid using his or her left arm, left hand, or other portions of
his or her left body for the performance of tasks, or even wash this side of the body (personal
neglect syndrome), almost not knowing that these parts of his or her body exist.
41.
42. Diseases of the Basal Ganglia in Humans
• Three distinct biochemical pathways in the basal ganglia normally operate in a
balanced fashion: (1) the nigrostriatal dopaminergic system, (2) the intrastriatal
cholinergic system, and (3) the GABAergic system, which projects from the
striatum to the globus pallidus and substantia nigra.
• When one or more of these pathways become dysfunctional, characteristic motor
abnormalities occur. Diseases of the basal ganglia lead to two general types of
disorders: hyperkinetic and hypokinetic.
• Athetosis consists of slow, writhing movement of the distal parts of the limbs.
• Chorea is characterized by rapid, flicking movement of the extremities and facial
muscles.
• Ballism is associated with violent, flailing movement of the limbs (ballistic
movement). Akinesia is difficulty in initiating movement and decreased
spontaneous movement. Bradykinesia is slowness of movement.
43. • Abnormal Function in the Putamen Circuit: Athetosis, Hemiballismus,
and Chorea
• when a portion of the circuit is damaged or blocked, certain patterns
of movement become severely abnormal.
• lesions in the globus pallidus frequently lead to spontaneous and
often continuous writhing movements of a hand, an arm, the neck, or
the face-movements called athetosis.
• A lesion in the subthalamus often leads to sudden flailing movements
of an entire limb, a condition called hemiballismus.
44. • Huntington Disease
• An autosomal dominant inherited disease, with the onset occurring most
often in adult life(30- 40years).
• Damage to GABnergic neurons of caudate nucleus and putamen to the
globus pallidus external segment releases inhibition, permitting the
hyperkinetic features of the disease to develop.
• Signs and symptoms: appear as Choreiform movements first involuntary
movements of the extremities and twitching of the face (facial grimacing).
Later, more muscle groups are involved. Speech becomes slurred and then
incomprehensible. Progressive dementia occurs with loss of memory and
intellectual capacity.
45. • Parkinson Disease
• Has both hypokinetic and hyperkinetic features Is a progressive disease of unknown cause that commences
between the ages of 45 and 55 years.
• It is associated with neuronal degeneration in the substantia nigra
• The dopamine secreted in the caudate nucleus and putamen is an inhibitory transmitter;
• Destruction of the dopaminergic neurons in the substantia nigra allow the caudate nucleus and putamen to
become overly active and possibly cause continuous output of excitatory signals to the corticospinal motor
control system.
• These signals could overly excite many or all of the muscles of the body, thus leading to rigidity.
• Tremor. This is the result of the alternating contraction of agonists and antagonists. The tremor is slow and
occurs most obviously when the limbs are at rest. It disappears during sleep.
• Rigidity. This differs from the rigidity caused by lesions of the upper motor neurons in that it is present to an
equal extent in opposing muscle groups.
• If the tremor is absent, the rigidity is felt as resistance to passive movement and is sometimes referred to as
plastic rigidity (lead pipe). If the tremor is present, the muscle resistance is overcome as a series of jerks,
called cogwheel rigidity.
46. Bradykinesia Akinesia
• Mask like face: The movements are slow, the face is expressionless, and the
voice is slurred and unmodulated.
• Staccato and stiff movements. Swinging of the arms in walking is lost.
• Postural disturbances. The patient stands with a stoop, and his or her arms
are flexed. The patient walks by taking short steps and often is unable to
stop. In fact, he or she may break into a shuffling run to maintain balance.
• There is no loss of muscle power and no loss of sensibility. Since the
corticospinal tracts are normal, the superficial abdominal reflexes are
normal, and there is no Babinski response. The deep tendon reflexes are
normal.
• other motor symptoms including dysphagia (impaired ability to swallow),
speech disorders, gait disturbances, and fatigue.
