Commissure of fornix

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Brain: Commissure of fornix
Diagram of the fornix.
Latin	c. fornicis
Gray's	subject #189 838
NeuroNames	hier-255
Dorlands/Elsevier	c_49/12251619

The lateral portions of the body of the fornix are joined by a thin triangular lamina, named the psalterium (lyra). This lamina contains some transverse fibers that connect the two hippocampi across the middle line and constitute the commissure of fornix (hippocampal commissure).

The terminal lamina creates the commisure plate. This structure gives existence to the corpus callosum, the septum pellucidum, and the fornix. The latter splits into two columnae fornicis (anterior), and then splits into two crus fornicis (posterior). These two crus are joined together through the commissura hippocampalis. The beginning of the splitting is called the psalterium or Lyra Davidis. The latter name is used because the structure resembles a lyra (or triangular harp): The two crus are the "chassis" of the lyra, and the commisure connections are the fibers.

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.

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)