1. Fornix : it arises from the hippocampus and terminates in the mamillary body. The fornix is formed of 4 parts:
a. Fimbria : is the continuation of alveus which is formed of axons of the neurons of the hippocampus and passes along its medial border.
b. Crus of the fornix: is the continuation of the fimbria below the splenium.
c. Body of the fornix: the two crura fuse to form the body of the fornix.
d. Anterior column of the fornix: each one terminates in the mamillary body.
2. Cingulum : is the fiber bundle of the limbic lobe.
3. Mamillothalamic tract : connects the mamillary body with the anterior thalamic nucleus.
4. Stria terminalis : it begins in the septal area and in the habenular nucleus.
Pes hippocampus Dentate gyrus Hippocampus Fimbria Columns of fornix Corpus callosum Head of caudate Septum pellucidum Collateral trigone Thalamus
Anterior column of fornix Body of fornix Crus of fornix Pes hippocampus Hippocampus Fimbria Dentate gyrus Splenium Stria terminalis Inf. horn of lat. vent. Commissure of fornix Head of caudate Corpus callosum Thalamus
1. Recent memory : the hippocampus plays a role in remembering the recent events.
2. Emotional behavior : it plays a role in anger, fear, and emotional behavior associated with sexual behavior.
Malfunction of the limbic system
The malfunction is involved in psychiatric disorder, including schizophrenia , depression , and senile dementia . Antipsychotic drugs block limbic dopamine receptors.
1. Lesion in the hippocampus causes loss of the recent memory.
2. In Alzheimer's disease , there is extensive degeneration in the hippocampus.
3. Lesions in the amygdaloid nucleus cause loss of the aggressive behavior, fear and anger .
Part Function Amygdala AGGRESSION and FEAR Cingulate gyrus AUTONOMIC FUNCTION Hippocampus RECENT MEMORY Hypothalamus ENDOCRINE FUNCTION Mammillary body LONG MEMORY Nucleus accumbens ADDICTION Prefrontal area PERSONALITY Parahippocampus SPATIAL MEMORY