Septum pellucidum
Encyclopedia
The septum pellucidum and not to be confused with the medial septum, is a thin, triangular, vertical 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.
and gray matter
, called the laminae septi pellucidi. During fetal development there is a space between the two laminae called the cavum septum pellucidum
which, in ninety per cent of cases, disappears during infancy. The cavum is occasionally referred to as the fifth ventricle but the term has lost favor in recent years, as the space is usually not continuous with the ventricular system and does not contain cerebrospinal fluid
. Indeed fifth ventricle has been used for other purposes in recent years.
s. It is attached inferior to the corpus callosum
, the large collection of nerve fibers that connect the two cerebral hemispheres. It is attached to the anterior part of the fornix, and on either side of the structure are the two lateral ventricles.
. Logically, the septum pellucidum is a septum in the medial plane and could therefore be termed 'medial septum', but this is incorrect. The term medial septum is reserved for a small group of nuclei which are closely associated with the septum pellucidum.
s in the gene
, is associated with septo-optic dysplasia
. This may result in hypothalamic
dysfunction and hypopituitarism
, as well as problems of vision, coordination, and intelligence, as well as other unusual symptoms.
Ventricular system
The ventricular system is a set of structures containing cerebrospinal fluid in the brain. It is continuous with the central canal of the spinal cord.-Components:The system comprises four ventricles:* right and left lateral ventricles* third ventricle...
of the brain. It runs as a sheet from the corpus callosum
Corpus callosum
The corpus callosum , also known as the colossal commissure, is a wide, flat bundle of neural fibers beneath the cortex in the eutherian brain at the longitudinal fissure. It connects the left and right cerebral hemispheres and facilitates interhemispheric communication...
down to the fornix.
Layers
The septum pellucidum actually consists of two layers or laminae of both whiteWhite matter
White matter is one of the two components of the central nervous system and consists mostly of myelinated axons. White matter tissue of the freshly cut brain appears pinkish white to the naked eye because myelin is composed largely of lipid tissue veined with capillaries. Its white color is due to...
and gray matter
Gray Matter
"Gray Matter" is a short story by Stephen King, first published in the October 1973 issue of Cavalier magazine, and later collected in King's 1978 collection Night Shift. It is set in the same area as King's novel Dreamcatcher.-Setting:...
, called the laminae septi pellucidi. During fetal development there is a space between the two laminae called the cavum septum pellucidum
Cavum septum pellucidum
Cavum septum pellucidum describes a septum pellucidum that has a separation between its two leaflets . This cavity contains cerebrospinal fluid that filters from the ventricles through the septal laminae....
which, in ninety per cent of cases, disappears during infancy. The cavum is occasionally referred to as the fifth ventricle but the term has lost favor in recent years, as the space is usually not continuous with the ventricular system and does not contain cerebrospinal fluid
Cerebrospinal fluid
Cerebrospinal fluid , Liquor cerebrospinalis, is a clear, colorless, bodily fluid, that occupies the subarachnoid space and the ventricular system around and inside the brain and spinal cord...
. Indeed fifth ventricle has been used for other purposes in recent years.
Location
The septum pellucidum is located in the midline of the brain, between the two cerebral hemisphereCerebral hemisphere
A cerebral hemisphere is one of the two regions of the eutherian brain that are delineated by the median plane, . The brain can thus be described as being divided into left and right cerebral hemispheres. Each of these hemispheres has an outer layer of grey matter called the cerebral cortex that is...
s. It is attached inferior to the corpus callosum
Corpus callosum
The corpus callosum , also known as the colossal commissure, is a wide, flat bundle of neural fibers beneath the cortex in the eutherian brain at the longitudinal fissure. It connects the left and right cerebral hemispheres and facilitates interhemispheric communication...
, the large collection of nerve fibers that connect the two cerebral hemispheres. It is attached to the anterior part of the fornix, and on either side of the structure are the two lateral ventricles.
Confusion over the term
The septum pellucidum is often confused with the septal nucleiSeptal nuclei
The septal area are structures that lie below the rostrum of corpus callosum in front of lamina terminalis , composed of medium-size neurons grouped into medial, lateral, and posterior groups...
. Logically, the septum pellucidum is a septum in the medial plane and could therefore be termed 'medial septum', but this is incorrect. The term medial septum is reserved for a small group of nuclei which are closely associated with the septum pellucidum.
Pathology
Absence of the septum pellucidum or corpus callosum, caused by mutationMutation
In molecular biology and genetics, mutations are changes in a genomic sequence: the DNA sequence of a cell's genome or the DNA or RNA sequence of a virus. They can be defined as sudden and spontaneous changes in the cell. Mutations are caused by radiation, viruses, transposons and mutagenic...
s in the gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
, is associated with septo-optic dysplasia
Septo-optic dysplasia
Septo-optic dysplasia , also known as de Morsier syndrome is a congenital malformation syndrome made manifest by hypoplasia of the optic nerve and absence of the septum pellucidum...
. This may result in hypothalamic
Hypothalamus
The Hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions...
dysfunction and hypopituitarism
Hypopituitarism
Hypopituitarism is the decreased secretion of one or more of the eight hormones normally produced by the pituitary gland at the base of the brain...
, as well as problems of vision, coordination, and intelligence, as well as other unusual symptoms.