Septum pellucidum

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. During fetal development, there is a space between the two laminae called the cave of septum pellucidum that, in ninety percent of cases, disappears during infancy. The cavum was occasionally referred to as the fifth ventricle, but this is no longer used because the space is usually not continuous with the ventricular system. The fifth ventricle is recognised as the terminal enlargement of the spinal cord.

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. 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. Management is directed at the symptoms a person is affected with.

Additional images

File:Gray744.png|Cross-section of the brain showing the septum pellucidum sitting between the two lateral ventricles, and beneath the corpus callosum File:Slide5oo.JPG|Septum pellucidum (labelled "septum lucidum") seen in a specimen from a cadaver.

References

References

1. (16 November 2007). "Anatomy of neuropsychiatry: the new anatomy of the basal forebrain and its implications for neuropsychiatric illness". Academic Press.
2. (2010). "The Brain and Behavior: An Introduction to Behavioral Neuroanatomy". Cambridge University Press.
3. (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.
4. (1989). "The cavum septi pellucidi: a fifth ventricle?". Acta Anat (Basel).
5. (2005). "Fifth ventricle: an unusual cystic lesion of the conus medullaris". Spinal Cord.
6. "Septo-optic dysplasia spectrum {{!}} Genetic and Rare Diseases Information Center (GARD) – an NCATS Program".