CSF, meninges, intro of the brain

The cerebrospinal fluid serves three purpose:

-Buoyancy :allows the brain to attain considerable size without being impaired by its own weight -Protection: protects the brain from striking the cranium when head is jolted. -Chemical stability: the flow of CSF rinses metabolic wastes from the nervous tissue and homeostatically regulates it chemical environment.

Two major dural sinuses are the?

-Superior sagittal sinus (found just under the cranium along the midsagittal line) Also is filled with venous blood. -Transverse sinus (Runs horizontally from the rear of the head toward each ear). These meet like a T at the back of the brain and empty into the internal jugular veins at the back of the neck.

The cerebellum lies inferior to the cerebrum in the posterior cranial fossa and is separated from the cerebrum by?

Transverse cerebral fissure.

BBS is an important protective device, it is an obstacle to the delivery of drugs such as_____?

antibiotics, cancer drugs, therefore complicates the tx of brain diseases.

A subdural space separates the dura from the___?

arachnoid

The ___ is the middle layer of the meninges, lying directly underneath the dura mater. It consists of layers of C.T., avascular, and does not receive any innervation.

arachnoid mater

Which layer of the meninges is avascular?

arachnoid mater

The blood brain barrier(BBB) isolates the blood from?

the brain tissue and limits what substances are able to get to the brain cells, thus protecting the neurons.

The brain is divided into three major portions. What is it?

(A) Cerebrum, (C) cerebellum, and (B) brainstem

Locations of the frontal section of the head. The meninges of the brain.

1) Superior sagittal 2) Subdural space 3) Arachnoid granulation 4) falx cerebri ( in longitudinal fissure only) 5) subarachnoid space (contains CSF) 6)pia mater 7) arachnoid trabeculae 8) arachnoid mater

The space between the sheath and vertebral bone, called the epidural space is occupied by?

Blood vessels, adipose tissue and loose connective tissue

Which major part of the brain is the smallest of them all and crucial for survival?

Brainstem. It is crucial for survival because it has such fundamental life support functions, such as a stroke and injuries in the brainstem are more likely to be fatal than comparable injuries to the cerebrum or cerebellum.

Step 3

CSF flows through the subarachnoid space.

Step 2

CSF flows through the ventricles and into the subarachnoid space via the median and lateral apertures. Some CSF flows through the central canal of the spinal cord

Step 4

CSF is absorbed into the dural venous sinuses via the arachnoid villi.

Step 1

CSF is produced by the choroid plexus of each ventricle.

What is the second largest region of the brain; it constitutes about 10% of its volume but contains over 50% of its neurons?

Cerebellum

What constitutes about 83% of it volume and consists of a pair of half globes called the cerebral hemispheres?

Cerebrum

The pia mater is a delicate , translucent membrane that closely follows the contours of the spinal cord. It continues beyond the medullary cone as a fibrous strand, terminal filum, forming part of the____________ that anchors the cord to the coccyx.

Coccygeal ligament

At regular intervals along the cord. Extensions of the pia called_____ extend thru the arachnoid to the dura, anchoring the cord and limiting side to side movements

Denticulate ligament

The brainstem major components from rostral to caudal are?

Diencephalon, midbrain, pons, and medulla oblongata.

The______ forms a loose fitting sleeve called the rural sheath around the spinal cord

Dura mater

Which two layers of the meninges is vascular?

Dura mater and Pia mater

What are the three layers of the meninges called? What is the overall function of the layers?

Dura mater, arachnoid mater, and pia mater. -They protect the brain and provide a structural framework for arteries ,veins and dural sinuses. -acting with cerebrospinal fluid to protect the CNS from mechanical damage.

Which meninges layer receives its own vasculature?

Dura mater; primarily from the middle meningeal artery and vein.

Anesthetics are introduce to the epidural space to block pain signals during childbirth or surgery; this procedure is called

Epidural anesthesia

Between the body vertebral and spinal dura mater is ?

Epidural space

What is the function of ependymal cells? Location?

Function: line cavities of the brain and spinal cord; secrete and circulate cerebrospinal fluid. location: CNS

A very DEEP GROOVE, separates the right and left hemispheres from each other is called? At the bottom of this fissure, the hemispheres are connected by a thick bundle of nerve fibers called?

Longitudinal fissure ; Corpus callosum

Inferior to the medullary cone , the subarachnoid space is called the____ and is occupied by the cauda equine and CSF

Lumbar cistern

What are the two directional terms often used to describe the brain anatomy?

Rostral and caudal In reference to the human brain: rostral means toward the forehead caudal means toward the spinal cord In reference to spinal cord and brainstem: rostral means higher and caudal means lower

Caudally, the brainstem ends at the foramen magnum of the skull and the central nervous system(CNS) continues below this as the?

Spinal cord.

Underneath the arachnoid is a space known as the_______? It contains cerebrospinal fluid, which acts to cushion the brain.

Subarachnoid space -is located where the (?) is.

The gap between the arachnoid and the pia mater is called?

Subarachnoid space, which is filled with CSF

Neurological diseases are diagnosed in part by examining CSF for bacteria, blood, white blood cells or abnormalities of chemical composition. Can't be perform if the patient has signs of high intracranial pressure.

The CSF is obtained by a procedure called a spinal tap or lumbar puncture. Needle is insert between the spinous processes of L3 & L4. Needle punctures the dura mater and enters the lumbar cistern.

The arachnoid mater consists of a simple squamous epithelium, the arachnoid membrane, adhering to the inside of the dura, and a loose mesh of collagenous and elastic fibers spanning the gap between?

The arachnoid membrane and the pia mater

Between the periosteal layer and meningeal layer, the dural(venous) sinuses are located.

They are responsible for the venous vasculature of the cranium, draining into the internal jugular veins.

endothelial cells

cells that line the walls of blood vessels.

From the fourth ventricle, towards the inferior end, the space narrows and forms a_______ that extends through the medulla oblongata into the spinal cord.

central canal

From the third ventricle a canal called__________, passes down the core of the midbrain and leads to the fourth ventricle, a small triangular chamber between the pons and cerebellum.

cerebral aqueduct

On the floor or wall of each ventricle, there is a spongy mass of blood capillaries called?

choroid plexus

Where does the blood have direct access to the brain tissue?

circumventricular organs (CVOs)

The BBB is absent from patches called___?

circumventricular organs (CVOs)- on the walls of third and fourth ventricles.

What is cerebrospinal fluid (CSF)?

clear, colorless liquid that fills the ventricles and canals of the CNS and bathes its external surface.

Brain gray matter: Gray matter, the site of the neurosomas, dendrites, and synapses, forms a surface layer called the ____ over the cerebrum and cerebellum, and deeper masses called _____ surrounded by white matter.

cortex ; nuclei

Brain white matter: The white matter thus lies deep to the ______, opposite from the relationship of gray and white matter in the spinal cord.

cortical gray matter in most of the brain.

The___ is the outermost layer of the meninges, lying directly underneath the bones of the skull and vertebral column. It is thick, tough and inextensible.

dura mater

Anything passing from the blood into the tissue fluid has to pass through the______?

endothelial cells

CSF formation begins with the filtration of plasma through the blood capillaries of the brain. The_____________ chemically modify the filtrate as it passes through them into the ventricles and subarachnoid space.

ependymal cells

What type of neuroglia covers each choroid plexus, entire interior surface of the ventricles, and the canals of the brain and spinal cord?

ependymal cells

At the choroid plexuses, there is a blood-CSF barrier, composed of?

ependymal cells joined by tight junctions.

The brain barrier system(BBS) is highly permeable to water;

glucose; lipid-soluble substances such as oxygen and carbon dioxide; and drugs such as alcohol, caffeine, nicotine, and anesthetics.

Each hemisphere is marked by thick FOLDS called_____, which are separated by a SHALLOW GROOVE called ____?

gyri or( singular word: gyrus) ; sulci or (singular word sulcus)

What is meningitis?

inflammation of the meninges. -It is caused by a variety of bacteria and viruses that invade the CNS by way of the nose and throat, often following respiratory, throat and ear infections. -bacteria most common: Neisseria meningitidis and streptococcus pneumoniae - diagnosed: examine the CSF for bacteria and white blood cells

Through a pore called ___________, each lateral ventricle is connected to the third ventricle, a narrow median space inferior to the corpus callosum.

interventricular foramen

The largest are the two___________, which form an arc in each cerebral hemisphere.

lateral ventricles

The meninges refer to the ?

membranous coverings of the brain and spinal cord.

Which only layer continues into the vertebral canal where it forms the dural sac around the spinal cord?

meningeal layer

The CNS is covered with three layers of protective covering called?

meninges

What are the three regions of the brainstem?

midbrain, pons, medulla oblongata

In the cranial cavity, the dura mater contains two connective tissue sheets called?

periosteal layer- lines the inner surface of the bones of the cranium. meningeal layer- deep to the periosteal layer inside the cranial cavity.

A subarachnoid space separates the arachnoid from the___?

pia

The ______ is located underneath the subarachnoid space. It is very thin and tightly adhered to the surface of the brain and spinal cord. It is the only covering to follow contours of the brain (the gyri and fissures) even dipping into the sulci.

pia mater

Small projections of arachnoid mater into the dura (known as arachnoid granulations) allow CSF to?

re-enter the circulation via the dural (venous) sinuses.

The blood brain barrier (BBB), seals?

seals nearly all of the blood capillaries throughout the brain tissue.

define brain barrier system

strictly regulates what substances get from the bloodstream into the tissue fluid of the brain.

Astrocytes function:

they have extension called perivascular feet, which contact the blood capillaries and stimulate the formation of tight junctions between the endothelial cells that line it to form a tight seal called the BLOOD- BRAIN BARRIER.

In the spinal cord, the white matter is composed of__________ (or bundles of axons), which here connect one part of the brain to another and to the spinal cord. The bright white color comes from___?

tracts; myelin

The brain has four internal chambers called?

ventricles