Septum pellucidum

The septum pellucidum (Latin for "translucent wall") is a thin, triangular, vertical double membrane separating the anterior horns of the left and right lateral ventricles of the brain. It runs as a sheet from the corpus callosum down to the fornix.

Septum pellucidum
Image showing the septum pellucidum, with other structures of the rhinencephalon also shown
Cross-section of the brain showing the right cerebral hemisphere. The septum pellucidum is seen as the sheet joining the corpus callosum to the fornix.
Details
LocationMidline of the brain
Identifiers
LatinSeptum pellucidum
(lamina septi pellucidi)
MeSHD012688
NeuroNames256
NeuroLex IDnlx_144186
TA98A14.1.09.262
TA25647
FMA61844
Anatomical terms of neuroanatomy

The septum is not present in the syndrome septo-optic dysplasia.

Structure

The septum pellucidum is located in the septal area in the midline of the brain between the two cerebral hemispheres. The septal area is also the location of the septal nuclei. It is attached to the lower part of the corpus callosum, the large collection of nerve fibers that connect the two cerebral hemispheres. It is attached to the front forward part of the fornix. The lateral ventricles sit on either side of the septum.

The septum pellucidum consists of two layers or laminae of both white and gray matter.[1] During fetal development there is a space between the two laminae called the cave of septum pellucidum which, in ninety per cent of cases, disappears during infancy.[2][3] The cavum was occasionally referred to as the fifth ventricle but this is no longer used as the space is usually not continuous with the ventricular system.[4] The fifth ventricle is recognised as the terminal enlargement of the spinal cord.[5]

Clinical significance

Absence of the septum pellucidum occurs in septo-optic dysplasia, a rare developmental disorder usually characterized by abnormal development of the optic disk and pituitary deficiencies.[6] Symptoms of septo-optic dysplasia are highly variable and may include vision difficulties, low muscle tone, hormonal problems, seizures, intellectual problems, and jaundice at birth.[6] Management is directed at the symptoms a person is affected with.[6]

Additional images
  • Cross-section of the brain showing the septum pellucidum sitting between the two lateral ventricles, and beneath the corpus callosum
  • Septum pellucidum (labelled "septum lucidum") seen in a specimen from a cadaver.

See also
This article uses anatomical terminology.

References
  1. Lennart Heimer; Gary W. Van Hoesen (16 November 2007). Anatomy of neuropsychiatry: the new anatomy of the basal forebrain and its implications for neuropsychiatric illness. Academic Press. p. 28. ISBN 978-0-12-374239-1. Retrieved 24 December 2010.
  2. David L. Clark; Nash N. Boutros; Mario F. Mendez (2010). The Brain and Behavior: An Introduction to Behavioral Neuroanatomy. Cambridge University Press. pp. 217–8. ISBN 978-0-521-14229-8. Retrieved 24 December 2010.
  3. Love J; Hollenhorst R (1956). "Bilateral palsy of the sixth cranial nerve caused by a cyst of the septum pellucidum (fifth ventricle) and cured by pneumoencephalography". Mayo Clin Proc. 31 (2): 43–6. PMID 13289891.
  4. Alonso J; Coveñas R; Lara J; Piñuela C; Aijón J (1989). "The cavum septi pellucidi: a fifth ventricle?". Acta Anat (Basel). 134 (4): 286–90. doi:10.1159/000146704. PMID 2741657.
  5. Liccardo G; Ruggeri F; De Cerchio L; Floris R; Lunardi P (2005). "Fifth ventricle: an unusual cystic lesion of the conus medullaris". Spinal Cord. 43 (6): 381–4. doi:10.1038/sj.sc.3101712. PMID 15655569.
  6. "Septo-optic dysplasia spectrum | Genetic and Rare Diseases Information Center (GARD) – an NCATS Program". rarediseases.info.nih.gov. Retrieved 2020-01-15.


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