Fornix

The fornix is a C-shaped bundle of fibres (axons) in the brain, and carries signals from the hippocampus to the mammillary bodies and septal nuclei.

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The fibres begin in the hippocampus on each side of the brain; the separate left and right side are each called the crus of the fornix. The bundles of fibres come together in the midline of the brain, forming the body of the fornix. The inferior edge of the septum pellucidum (a membrane the separates the left and right ventricles) is attached to the upper face of the fornix body.

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When the body is formed from the two crura (sing. crus), there is a small number of fibres that cross over to the other side at what is called the hippocampal commissure. Most fibres stay on their original side.

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The body of the fornix travels anteriorly and divides again near the anterior commissure. The left and right parts reseparate, but there is also an anterior/posterior divergence. The posterior fibres (called the postcommissural fornix) of each side continue through the hypothalamus to the mammillary bodies. The anterior fibers (precommissural fornix) end at the septal nuclei of each half of the brain.

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Axon: An axon, or "nerve fiber," is a long slender projection of a nerve cell, or "neuron," which conducts electrical impulses away from the neuron's cell body or soma. Axons are in effect the primary transmission lines of the nervous system, and as bundles they help make up nerves. Individual axons are m...

Brain: :For other articles about other subjects named brain see brain (disambiguation). For information about the human brain in specific, please see its article....

Hippocampus: The hippocampus is a part of the brain located inside the temporal lobe (humans have two hippocampi, one in each side of the brain). It forms a part of the limbic system and plays a part in memory and navigation. The name derives from its curved shape, which supposedly resembles that of a seahorse (...