Fornix of brain

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

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.

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 that separates the two lateral ventricles) is attached to the upper face of the fornix body.

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.

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.

[edit] Additional images

Velum interpositum.	Mesal 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)
primary sulci/fissures	medial longitudinal, lateral, central, parietoöccipital, calcarine, cingulate
frontal lobe	precentral gyrus (primary motor cortex, 4), precentral sulcus, superior frontal gyrus (6, 8), middle frontal gyrus (46), inferior frontal gyrus (Broca's area, 44-pars opercularis, 45-pars triangularis), prefrontal cortex (orbitofrontal cortex, 9, 10, 11, 12, 47)
parietal lobe	postcentral sulcus, postcentral gyrus (1, 2, 3, 43), superior parietal lobule (5), inferior parietal lobule (39-angular gyrus, 40), precuneus (7), intraparietal sulcus
occipital lobe	primary visual cortex (17), cuneus, lingual gyrus, 18, 19 (18 and 19 span whole lobe)
temporal lobe	transverse temporal gyrus (41-42-primary auditory cortex), superior temporal gyrus (38, 22-Wernicke's area), middle temporal gyrus (21), inferior temporal gyrus (20), fusiform gyrus (36, 37)
limbic lobe/fornicate gyrus	cingulate cortex/cingulate gyrus, anterior cingulate (24, 32, 33), posterior cingulate (23, 31), isthmus (26, 29, 30), parahippocampal gyrus (piriform cortex, 25, 27, 35), entorhinal cortex (28, 34)
subcortical/insular cortex	rhinencephalon, olfactory bulb, olfactory tract, corpus callosum (splenium, genu, rostrum), lateral ventricles, septum pellucidum, ependyma, internal capsule, corona radiata, external capsule, fornix (commissure of fornix), anterior commissure, posterior commissure
hippocampal formation	dentate gyrus, hippocampus, subiculum
basal ganglia	striatum (caudate nucleus, putamen), lentiform nucleus (putamen, globus pallidus), claustrum, extreme capsule, amygdala, nucleus accumbens
Some categorizations are approximations, and some Brodmann areas span gyri.