The septum pellucidum (
Latin
Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...
for "translucent wall") is a thin, triangular, vertical double membrane separating the
anterior horns of the left and right
lateral ventricles of the
brain
The brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It consists of nervous tissue and is typically located in the head (cephalization), usually near organs for ...
. It runs as a sheet from the
corpus callosum
The corpus callosum (Latin for "tough body"), also callosal commissure, is a wide, thick nerve tract, consisting of a flat bundle of commissural fibers, beneath the cerebral cortex in the brain. The corpus callosum is only found in placental ...
down to the
fornix.
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 hemisphere
The vertebrate cerebrum (brain) is formed by two cerebral hemispheres that are separated by a groove, the longitudinal fissure. The brain can thus be described as being divided into left and right cerebral hemispheres. Each of these hemispheres ...
s. 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 ventricle
The lateral ventricles are the two largest ventricular system, ventricles of the brain and contain cerebrospinal fluid. Each cerebral hemisphere contains a lateral ventricle, known as the left or right lateral ventricle, respectively.
Each later ...
s sit on either side of the septum.
The septum pellucidum consists of two layers or ''laminae'' of both
white
White is the lightest color and is achromatic (having no chroma). It is the color of objects such as snow, chalk, and milk, and is the opposite of black. White objects fully (or almost fully) reflect and scatter all the visible wa ...
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
The spinal cord is a long, thin, tubular structure made up of nervous tissue that extends from the medulla oblongata in the lower brainstem to the lumbar region of the vertebral column (backbone) of vertebrate animals. The center of the spinal c ...
.
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
Jaundice, also known as icterus, is a yellowish or, less frequently, greenish pigmentation of the skin and sclera due to high bilirubin levels. Jaundice in adults is typically a sign indicating the presence of underlying diseases involving ...
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
A cadaver, often known as a corpse, is a Death, dead human body. Cadavers are used by medical students, physicians and other scientists to study anatomy, identify disease sites, determine causes of death, and provide tissue (biology), tissue to ...
.
See also
References
External links
{{Authority control
Cerebrum
Ventricular system