Fornix of brain

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Brain: Fornix of brain
Diagram of the fornix. Right=anterior
Scheme of rhinencephalon.
Gray's	subject #189 838
NeuroNames	hier-250
MeSH	Fornix+(Brain)

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

[edit] Structure

The fibres begin in the hippocampus on each side of the brain (where they are also known as the fimbria); 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 that separates the two lateral ventricles) is attached to the upper face of the fornix body.

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; then to the anterior nuclei of thalamus, which maps to cingulate cortex.
• The anterior fibers (precommissural fornix) end at the septal nuclei and nucleus accumbens of each half of the brain.

[edit] Additional images

Velum interpositum.	Medial aspect of a brain sectioned in the median sagittal plane.	Coronal section of brain through intermediate mass of third ventricle.	Coronal section of lateral and third ventricles.
Central part and anterior and posterior cornua of lateral ventricles exposed from above.	Tela chorioidea of the third ventricle, and the choroid plexus of the left lateral ventricle, exposed from above.	Diagram showing the positions of the three principal subarachnoid cisternæ.

[edit] External links

• Photo at umdnj.edu
• BrainMaps at UCDavis Fornix

• Roche Lexicon - illustrated navigator, at Elsevier 13048.000-3

v • d • e Brain: telencephalon (cerebrum, cerebral cortex, cerebral hemispheres) Frontal lobe Precentral gyrus (Primary motor cortex, 4) Superior frontal gyrus/Frontal eye fields (6, 8, 9), Middle frontal gyrus (46), Inferior frontal gyrus/Broca's area (44-Pars opercularis, 45-Pars triangularis) Orbitofrontal cortex (10, 11, 12, 47) Prefrontal cortex, Premotor cortex Precentral sulcus - Superior frontal sulcus - Inferior frontal sulcus - Olfactory sulcus Parietal lobe Somatosensory cortex (Primary (1, 2, 3, 43), Secondary (5)), Precuneus (7m) - Parietal operculum Parietal lobules (Superior (7l), Inferior (40)), Angular gyrus (39) Intraparietal sulcus, Marginal sulcus Occipital lobe Primary visual cortex (17), (Cuneus, Lingual gyrus, Lateral occipital gyrus (18, 19)) Calcarine fissure Temporal lobe Primary auditory cortex (41, 42), Superior temporal gyrus (38, 22/Wernicke's area), Middle temporal gyrus (21), Inferior temporal gyrus (20) Fusiform gyrus (37) Medial temporal lobe (Amygdala, Parahippocampal gyrus (27, 28, 34, 35, 36) Cingulate cortex/gyrus Subgenual area (25), Anterior cingulate (24, 32, 33), Posterior cingulate (23, 31), Retrosplenial cortex (26, 29, 30) Callosal sulcus Interlobar sulci/fissures lateral: Central (frontal+parietal), Lateral (frontal+parietal+temporal), Parietoöccipital medial: Medial longitudinal, Cingulate (frontal+cingulate), Collateral (temporal+occipital) White matter tracts Commissural fibers - Association fibers Internal capsule (Anterior limb, Genu, Posterior limb), Corona radiata, External capsule, Lamina terminalis, Extreme capsule, Semioval center Olfactory tract - Terminal stria - Diagonal band of Broca Other Insular cortex gray: Olfactory bulb, Anterior olfactory nucleus, Basal optic nucleus of Meynert, Substantia innominata, Anterior perforated substance Corpus striatum - Limbic lobe Some categorizations are approximations, and some Brodmann areas span gyri.

v • d • e White matter fibers Association fibers Uncinate fasciculus - Cingulum - Superior longitudinal fasciculus/Arcuate fasciculus - Inferior longitudinal fasciculus - Inferior occipitofrontal fasciculus - Fornix (Columns of fornix, Crus of fornix) Commissural fibers Corpus callosum (Genu, Splenium, Tapetum, Rostrum) - Anterior commissure - Posterior commissure - Commissure of fornix Projection fibers (none named)

v • d • e Papez circuit Diencephalon Mammillary body → Mammillothalamic tract → Anterior thalamic nucleus → Telencephalon Anterior limb of internal capsule → Cingulate gyrus → Cingulum → Parahippocampal gyrus → Entorhinal cortex → Perforant path → Hippocampus/Hippocampal formation (Subiculum) → Fornix →