2

Limbic System

Limbic lobeHippocampal formatiomHipocampus

Limbic SystemLimbic Lobe (Cortex) Related Subcortical Nuclei

Hippocampal formation Amygdala

Septal Area

Parahippocampal gyrus

Cingulate gyrus

Insula

Some parts of Diencephalon

Some nuclei of Midbrain

Corticomedial group

Bsolateral group

4

Limbus = A ring

• A ring of cortex around Corpus Callosum and Diencephalon

5

Hippocampal formation

Hippocampus Dentate Subiculum

6

Anatomy of Hippocampus

8

Limbic functions

Regulate Emotional & Motivational

aspect of Behaviour

Changing short-termMemory into long-term

Memory (Learning)

10

Cornu Ammonis

• Hippocampus = Ammon,s horn (Cornu) after Egyptian deity with ram,s head

• For research purpose, it is divided into 4 cornu ammonis (CA) zones :– CA1– CA2– CA3– CA4

Connections of hippocampus• 1- Perforant pathway from entorhinal

area to dentate gyrus • 2- Axons from dentate to pyramidal cell

in CA3 sector• 3- Axons from CA3 to fimbria• 4- A branch from the CA3 fiber called

Schaffer collateral, projects to CA1• 5- CA1 projects to entorhinal cortex

Afferent Connections to Hippocampus

• 10 Groups of fibers pass to Hippocampus:• 1- Fibers from cingulate gyrus • 2- Fibers from septal area• 3- Fibers from opposite hippocampus• 4- Fibers from indusium grisum• 5- Fibers from enthorhinal or olfactory area• 6- Fibers from dentate and subiculum

Afferents connections cont…

• 6- From auditory, visual, olfactory association cortex

• 7- Cholinergic fibers from septal area • 8- Noradrenergic fibers from ceruleus

nucleus • 9- Cerotonergic fibers from raphe nuclei• 10- Dopaminergic fibers from ventral

tegmental area

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Branches Of Basilar Artery• Pontine• Labyrinthine Artery• Anterior Inferior

Cerebellar Artery• Superior Cerebellar

Artery• Posterior Cerebral

Artery

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Coronal plane of Sinus Cavernous Looking from front to back

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Lenticulostriate Arteries Supply the Basal Ganglia and Internal Capsule

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Arterial Supply of the Thalamus and Basal Ganglia

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Superficial and Deep Arterial Supply to the Cerebral HemispheresCoronal Plane

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Superficial and Deep Arterial Supply to the Cerebral HemisphereHorizontal Plane

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Interrelationships of the pia mater and the perivascular (Virchow-Robin) spaces in

the human cerebrum.

ARACHNOID VILLI AND GRANULATIONS

• extensions of the arachnoid mater and subarachnoid space through the wall of dural venous sinuses.

• the major pathway for the passage of CSF from the subarachnoid space into the blood.

DURAL PARTITIONS • Falx cerebri • Tentorium cerebelli in front there is a gap, the

tentorial incisure, for passage of midbrain, trigeminal cave

• Falx cerebelli • Diaphragma sellae important landmark structure

in pituitary surgery

Circulation and drainage • Most of the CSF is secreted by the

choroid plexuses in the lateral, third and fourth ventricles.

• The total CSF volume is 125 ml. The ventricles contain 25 ml and the remaining 100 ml is located in the cranial subarachnoid space.

• CSF is absorbed into the venous system through arachnoid villi associated with the major dural venous sinuses, predominantly the superior sagittal sinus.

Circulation of cerebrospinal fluid

CSF drains from lateral ventricle interventricular foramina third ventricle

mesencephalic aqueduct fourth ventricle median and two lateral apertures

subarachnoid space arachnoid granulations superior sagittal sinus vein

positions of the principal subarachnoid cisterns

• cisterna magna or cerebellomedullary cistern

• pontine cistern • interpeduncular cistern • cistern of the lateral fossa • cistern of the great cerebral

vein (cisterna ambiens or superior cistern)

• prechiasmatic and postchiasmatic cistern

• cistern of the lamina terminalis

• supracallosal cistern