Septum pellucidum

Infobox Brain
Name = Septum pellucidum
Latin =
GraySubject = 189
GrayPage = 840


Caption = Scheme of rhinencephalon. (Septum pellucidum visible at top center.)

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Caption2 = Median sagittal section of brain. (Septum pellucidum visible at center.)
IsPartOf =
Components =
Artery =
Vein =
BrainInfoType = hier
BrainInfoNumber = 238
MeshName = Septum+Pellucidum
MeshNumber = A08.186.211.276.814
Dorlands = nine/20800743
DorlandsID = Septum pellucidum
The septum pellucidum (also called the septum lucidum) is a thin, triangular, vertical membrane that separates the lateral ventricles of the brain. It separates the anterior horn of the left and right lateral ventricles. It runs as a sheet from the corpus callosum down to the fornix. When the hemispheres are cut apart, the septum remains on one hemisphere, usually the left. The septum pellucidum is currently believed to have no particularly special functional importance.

Layers

The septum pellucidum actually consists of two layers or "laminae" of both white and gray matter, called the "laminae septi pellucidi".

These layers are normally fused; however, in approximately one-tenth of humans, there is a slit-like cavity between them, referred to as cavum septum pellucidum, cavum septi pellucidi, or "fifth ventricle" [DorlandsDict|two/000018335|Cavity of septum pellucidum] [cite journal | author = Love J, Hollenhorst R | title = Bilateral palsy of the sixth cranial nerve caused by a cyst of the septum pellucidum (fifth ventricle) and cured by pneumoencephalography | journal = Mayo Clin Proc | volume = 31 | issue = 2 | pages = 43–6 | year = 1956 | pmid = 13289891] . The last term has lost favor in recent years, as the space is usually not continuous with the ventricular system and does not contain cerebrospinal fluid [cite journal | author = Alonso J, Coveñas R, Lara J, Piñuela C, Aijón J | title = The cavum septi pellucidi: a fifth ventricle? | journal = Acta Anat (Basel) | volume = 134 | issue = 4 | pages = 286–90 | year = 1989 | pmid = 2741657] . Indeed "fifth ventricle" has been used for other purposes in recent years. [cite journal | author = Liccardo G, Ruggeri F, De Cerchio L, Floris R, Lunardi P | title = Fifth ventricle: an unusual cystic lesion of the conus medullaris | journal = Spinal Cord | volume = 43 | issue = 6 | pages = 381–4 | year = 2005 | pmid = 15655569 | doi = 10.1038/sj.sc.3101712] .

Location

The septum pellucidum is located in the midline of the brain, between the two cerebral hemispheres. It is attached superiorly (above), anteriorly (in front), and inferiorly (below) to the corpus callosum, the large collection of nerve fibers that connect the two hemispheres.

Inferiorly and posteriorly (in back), it is attached to the anterior part of the fornix.

On either side are the two lateral ventricles, pockets of cerebrospinal fluid within the cerebral hemispheres.

Pathology

Absence of the septum pellucidum or corpus callosum, caused by mutations in the Gene|HESX1 gene, is associated with septo-optic dysplasia. This may result in hypothalamic dysfunction and hypopituitarism, as well as problems of vision, coordination, and intelligence, among other abnormalities.

One famous reference to an abnormality of the septum pellucidum would be the movie Rocky V. In the movie, the main character Rocky Balboa is forced to retire due to brain damage sustained throughout his career.

=Additional

References

* Gray, Henry & Clemente, Carmine D. (1984). "Gray's Anatomy of the Human Body" (30th ed.). New York: Lippincott Williams & Wilkins.

* Kasper, Dennis L.; Braunwald, Eugene; Fauci, Anthony S.; Hauser, Stephen L.; Longo, Dan L.; Jameson, J. Larry; & Kurt J. Isselbacher, (Eds.) (2004). "Harrison's Principles of Internal Medicine" (16th ed.). New York: McGraw-Hill.

External links

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