CEREBRUM

MAJ RISHI POKHRELMBBS, MD

NAIHSwww.slideshare.net

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CEREBRUM• Cerebral cortex

– Gross anatomy– Sulci and gyri– Functional areas

• White matter• Ventricular system

Borders and surfaces• 3 borders

– Superomedial

– Inferolateral with seprciliary

– Medial• Medial orbital

• Medial occipital

• 3 surfaces– Superolateral

– Medial

– Inferior• Orbital

• tentorial

7

• 3 Poles

superolateral surface

medial surface

inferior surface

Lobes

Insula

Sulci and gyri

a: pars orbitalisb: pars triangularisC: pars opercularis

Functional areas of brain

• Brodmann's area – 47 -52• Based on cytoarchitectonics • Sensory and motor, Primary and association • Multimodal association areas (75%)• Previously denoted by Ms or Sm now by nos

Primary motor areaPrimary sensory areaPremotor area

Frontal eye field

Motor speech (Broca’s) areaLanguage comprehension(Wernicke’s) area

Primary visual area

Leg Leg

Arm Arm

FaceFace

Pharynx

Larynx

Important Areas

Auditory area

Frontal Lobe

Frontal Lobe

Parietal Lobe

Parietal Lobe

Parietal Lobe

43

Temporal Lobe

Occipital Lobe

Medial Surface

Homunculus

Important Areas

Important Areas

Applied anatomy

• Collection of nerve fibres: Tracts, Fasciculi,

Lemnisci, Peduncles, Commissure etc.

• Myelination: Oligodendrocytes in CNS &

Schwann cells in PNS

• Collection of nerve cell bodies within white

matter of CNS: nuclei

WHITE MATTER OF CEREBRUM

CLASSIFICATION OF NERVE FIBERS

• Association Fibres: Connect

different cortical areas of the

same hemisphere

• Commissural Fibres: Connect

wide areas of Cx of both

hemispheres across midline

• Projection Fibres: Connect

cerebral cx with subcortical

grey matter of BG, Thalamus,

Brain stem & Spinal cord

ASSOCIATION FIBRES

Short and Long

LONG ASSOCIATION FIBRES

• Uncinate Fasciculus : – Connects Broca’s area

with Temp pole & Superior Temp Gyrus

– Expression of speech• Cingulam :

– Connects various parts of Limbic lobe (Cingulate & Parahippocampal gyri)

• Sup Longitudinal Fasciculus : Lateral to Corona radiata– Frontal lobe with visual

asso areas & Temporal lobe

• Fronto-occipital fasciculus : Medial to C Radiata– Frontal lobe with

Occipital & Temp lobes• Inferior Longitudinal

Fasciculus : Temp lobe with Areas 18 & 19 of occipital lobe

COMMISSURAL FIBRES

Types:• Homotopical : Connect

identical areas• Heterotopical : Connect

non-identical areas

Examples :• Corpus callosum • Ant commissure, Post

commissure • Hippocampal &

Habenular commissures

AP

CORPUS CALLOSUM

• Largest band of commissural fibres which connects wide areas of Neocortex except lower and ant parts

of temporal lobe

• Well developed in man

• 300 million finely myelinated fibres

• 10 cms long

Location :

• Ant end : 4cm behind frontal pole • Post end : 6cm in front of Occipital pole

AP

CORPUS CALLOSUM

PARTS : Splenium, Trunk, Genu, Rostrum

• Rostrum - continuous below with Lamina terminalis

A P

Forceps Major

Forceps Minor

CORPUS CALLOSUM

• Rostrum: orbital surfaces of 2 frontal lobes• Forceps minor: fibers of genu – 2 frontal lobes• Tapetum: fibers of trunk and splenium – do

not intersect with corona radiata, forms roof and lateral wall of post horn and lateral wall of inferior horn of lateral ventricles.

• Forceps major: fibers of splenium – 2 occipital lobes.

CORPUS CALLOSUM : TAPETUM

TAPETUMForceps major

LAT VENTRICLE : POSTERIOR HORN

LAT VENTRICLE : INFERIOR HORN

TAPETUM OF CC

Stria terminalis (Med)

Tail of Caudate Nu

INF HORN

Collateral eminence

CORPUS CALLOSUM

Function : • Interhemispheric transfer of information essential for

bilateral response & learning process

Applied : • congenital absence / surgical divn does not produce

any serious neurological deficit

Split brain syndrome :

COMMISSURAL FIBRES – Cont’d

• Ant commissure : – Ant part : Allocortex– Post part : Neocortex

• Post commissure : – Connect Sup colliculi, Pretectal nuclei, Nu of post

commissure, Interstitial nu etc.– Role in consensual pupillary light reflex

• Hippocampal commissure : Connects crura of Fornix• Habenular commissure : Connect habenular Nu (Limbic

system)

WHITE MATTER : CEREBRUM

PROJECTION FIBRES

• Connect cerebral cx with

subcortical grey matter like BG,

Thalamus, Brain stem & Spinal

cord.

• Cortico-fugal & cortico-petal

fibres

• E.g. Corona radiata & Int

capsule of Neo cortex

Fimbriae & Fornix of Allocortex

CORONA RADIATA

• Fan shaped arrangement of projection fibers from neo-cortex converging to the periphery of Corpus striatum

• Continues below as Internal capsule

CORONA RADIATA

INTERNAL CAPSULE• A compact band of

neocortical projection fibres

• Main highway for input &

output fibres of cerebral cx

• Continues above as corona

radiata & below as crus

cerebri of midbrain

• V- shaped in horizontal

section with concavity

laterally

RELATIONS : • Medial : Head of Caudate Nu & Thalamus• Lateral : Lentiform Nucleus

MedialExtreme capsule

Lateral

INTERNAL CAPSULE HORIZANTAL SECTION

• Ant Limb

• Genu

• Post limb

• Retrolentiform part

• Sublentiform part

ARRANGEMENT OF FIBRES :

:

Cortico-reticular

Ant Thalamic radiationAnt Thal Nu –Cingulate Gyrus (Papez

Circuit)Fibres of MF Bundle

ARRANGEMENT OF FIBRES : GENU

• Cortico- nuclear fibres : from areas 4, 6 & 8 to

motor nuclei of cranial nerves (contralateral)

• Superior Thalamic radiation : Thalamus to pre &

post central gyri of cerebral cortex

• Corticoreticular

ARRANGEMENT OF FIBRES: POSTERIOR LIMB – From Globus pallidus

• To Subthalamic nucleus (Fasciculus subthalamicus)

• To Thalamus (Fasciculus Lenticularis)– Nigro - striate (Comb bundle)

• From Substantia Nigra to Caudate Nu & Putamen

– Thalamo-striate : From intralaminar & centromedian Nu to Caudate Nu & Putamen

ARRANGEMENT OF FIBRES: SUBLENTIFORM PART• Auditory Radiation

– MGB to Anterior Transverse Temp gyrus & Sup temporal gyrus– Perception of hearing

• Meyer’s loop of optic radiation– from lower part of peripheral retina to visual Cortex

• Temporo - pontine & Parieto – pontine fibres

ARRANGEMENT OF FIBRES: RETROLENTIFORM PART

- Optic Radiation : LGB to Area 17

- Area 18,19 to Sup Colliculus & Motor Nu of EO Muscles for conjugated movements of eye

balls

- Parieto & Occipeto - pontine fibres

- Post Thalamic Radiation : Pulvinar (thalamus) to Areas 18,19, 39, 40)

ARTERIAL SUPPLY OF I C

Striate br of MCA

Recurrent branch of ACA

Striate br of AC A

Ant Limb

Genu

Sublentiform part

Post Limb

Retrolentiform part

Ant cerebral Artery

Int Carotid ArteryMiddle cerbral A

Post Cerebral Atery

Ant choroidal A

By central branches of cerebral arteries - End arteries

70

INT CAPSULE : BLOOD SUPPLY

ARTERY

PART OF IC

Striate Br of ACA

Rec Br of ACA

Striate Br of MCA(Charcot’s artery)

Direct Br from ICA

Ant Choroidal A

P CA

Ant Limb Genu

Post LimbS L Part

RL Part

By central branches of cerebral arteries - End arteries

APPLIED ANATOMY

• Cerebrovascular accident (CVA) affecting int capsule cause extensive clinical effects – Blood supply by end arteries– Dense collection of fibres in IC– Caused commonly by hemorrhage from Charcot’s

artery• Hemiplegia :

– UMN type paralysis of one half of the body – Commonly caused by CVAs affecting IC

Ventricular system

• Communicate with each other & with SA Space (thru roof of 4th Ventricle)

• Allow free flow of CSF produced by Choroid plexus

PART SUB DIVN CAVITY

FORE BRAINTelencephalon Lateral ventricle(s)

Diencephalon 3rd Ventricle

MID BRAIN Cerebral Aqueduct

HIND BRAIN 4th Ventricle

SP CORD Central canal

LATERAL VENTRICLE

• Cavity of Telencephalon

• One in each cerebral hemisphere

• Roughly ‘C’- shaped

• Capacity : 7-10ml

PARTS :

• Body (Central part)

• Anterior (Frontal lobe)

• Posterior (Occipital lobe)

• Inferior (Temporal lobe)

Task

• Draw a labeled diagram of

– Coronal section through

• Ant horn of lat ventricle

• Body of lat ventricle

• Inf horn of lateral ventricle

• Post horn of lat ventricle

– Floor of 4th ventricle

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