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 a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...

for "translucent wall") is a thin, triangular, vertical double membrane separating the anterior horns of the left and right lateral ventricles of the

brain A brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as Visual perception, vision. I ...

. 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 m ...

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 The septal area (medial olfactory area), consisting of the lateral septum and medial septum, is an area in the lower, posterior part of the medial surface of the frontal lobe, and refers to the nearby septum pellucidum. The septal nuclei are loca ...

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 hemisphere ...

s. The septal area is also the location of the

septal nuclei The septal area (medial olfactory area), consisting of the lateral septum and medial septum, is an area in the lower, posterior part of the medial surface of the frontal lobe, and refers to the nearby septum pellucidum. The septal nuclei are loc ...

. It is attached to the lower part of the

, 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 ventricles of the brain and contain cerebrospinal fluid (CSF). Each cerebral hemisphere contains a lateral ventricle, known as the left or right ventricle, respectively. Each lateral ventricle resemble ...

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 hue). It is the color of objects such as snow, chalk, and milk, and is the opposite of black. White objects fully reflect and scatter all the visible wavelengths of light. White ...

and gray matter. During fetal development, there is a space between the two laminae called the

cave of septum pellucidum The cave of septum pellucidum (CSP), cavum septi pellucidi, or cavity of septum pellucidum is a slit-like space in the septum pellucidum that is present in fetuses but usually fuses during infancy. The septum pellucidum is a thin, laminated transl ...

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 ventricular system is a set of four interconnected cavities known as cerebral ventricles in the brain. Within each ventricle is a region of choroid plexus which produces the circulating cerebrospinal fluid (CSF). The ventricular system is co ...

. The

fifth ventricle The central canal (also known as spinal foramen or ependymal canal) is the cerebrospinal fluid-filled space that runs through the spinal cord. The central canal lies below and is connected to the ventricular system of the brain, from which it ...

is recognised as the terminal enlargement of the

spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the sp ...

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 In vertebrate anatomy, the pituitary gland, or hypophysis, is an endocrine gland, about the size of a chickpea and weighing, on average, in humans. It is a protrusion off the bottom of the hypothalamus at the base of the brain. The hypoph ...

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 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 abnormal heme meta ...

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 or corpse is a dead human body that is used by medical students, physicians and other scientists to study anatomy, identify disease sites, determine causes of death, and provide tissue to repair a defect in a living human being. Stud ...

References

External links

{{Authority control Cerebrum Ventricular system

Structure

Clinical significance

Additional images

See also

References

External links