Cranium, Scalp, Meninges & Brain Flashcards
The bony ___ provides rigid support for the brain
cranium
Protective connective tissue membranes called ___ surround and partition portions of the brain
meninges
_____ fluid acts as a cushioning fluid
cerbrospinal
What is the purpose of the blood-brain barrier?
to prevent entry of harmful materials from the bloodstream
What are the three dense regular CT layers that separate the soft tissue of the brain from the bones of the cranium referred to as?
cranial meninges
What is the function of the cranial meninges?
enclose and protect blood vessels that supply the brain, contain and circulate CSF
True or false?
Parts of the cranial meninges form some of the veins that drain blood from the brain
true
Name the following meninge:
Tough membrane composed of two fibrous layers; strongest of the meninges
dura mater
What are the two layers of the dura mater?
periosteal layer: superficial
meningeal layer: deep
Name the following meninge:
lies immediately internal to the dura mater; partially composed of a delicate web of collagen and elastic fibers
Arachnoid
Immediately deep to the arachnoid is the ___ space
subarachnoid
Name the following cranial meninge:
innermost of the cranial meninges, thin layer of CT that tightly adheres to the brain and follows every contour of the brain surface
pia mater
The meningeal layer of the dura mater extends as flat partitions deep into the cranial cavity at four locations called what?
cranial dural septa
Name the 4 dura septa
falx cerebri; tentorium cerebelli; falx cerebelli; diaphragma selfae
What sinuses are found in the dura septa?
superior and inferior sagittal sinuses, the straight sinus, the sigmoid sinus, and the transverse sinus
Where does CSF circulate?
in the ventricles and subarachnoid space
The CSF bathes the exposed surfaces of the ___ ___ ___ and completely surrounds it
central nervous system
What 3 important functions does CSF perform?
buoyancy
protection
environmental stability
What is CSF formed by?
choroid plexus in each ventricle
What is CSF produced by?
secretion of fluid from the ependymal cells that originate from the blood plasma
CSF is similar to blood plasma but has some differences in ion concentration. What are the differences?
contains more sodium, hydrogen, and calcium; contains less potassium
Cavities or expansions within the brain that are derived from the lumen of the embryonic neural tube are called what?
brain ventricles
Brain ventricles are continuous with one another as well as with the ___ __ of the spinal cord
central canal
Four ventricles are located in the brain. Describe them.
two lateral ventricles are in the cerebrum; within the diencephalon is a smaller ventricle called the third ventricle; the fourth ventricle is located within the pons and cerebellum
In regards to the two lateral ventricles in the cerebrum, they are separated by a thin medial partition called what?
septum pellucidum
CSF flows from the third ventricle through the ___ ___ into the fourth ventricle
mesencephalic aquaduct
As the CSF flows through the subarachnoid space, it removes waste products and provides ___ to support the brain
buoyancy
What happens to excess CSF?
flows into the arachnoid villi, then drains into the dural venous sinuses
True or false?
The greater pressure on the CSF in the subarachnoid space assures that CSF moves into venous sinuses
true
This condition has been called “water on the brain” and is typically caused by an obstruction in CSF flow that restricts it reabsorption in the venous bloodstream
hydrocephalus
How is hydrocephalus treated?
by inserting a ventriculoperitoneal shunt that drains to the abdominal cavity; or a ventriculostomy that creates a hole in the floor of the third ventricle that drains into the subarachnoid space
This prevents exposure of neurons in the brain to drugs, waste products in the blood, and variations in levels of normal substances that could have adverse affect on brain function
blood-brain barrier
What type of junctions in the blood-brain barrier prevent materials from diffusing across the capillary wall?
tight junctions
____ act as “gatekeepers” that permit materials to pass to the neurons after leaving the capillaries
astrocytes
The blood-brain barrier is reduced or missing in three distinct locations in the CNS, what are they?
choroid plexus; hypothalamus; pineal gland
