1/1/2016 1 Meninges CSF The Nervous System Introduction • Protection of the brain – Bone (skull) – Membranes (meninges) – Watery cushion (cerebrospinal fluid) – Blood-brain barrier (astrocytes) The Meninges • Series of membranes • Cover and protect the CNS • Anchor and cushion the brain • Contain cerebrospinal fluid (CSF) The Meninges • Three layers – Dura mater – Arachnoid mater – Pia mater Figure 12.24 Skin of scalp Periosteum Falx cerebri (in longitudinal fissure only) Blood vessel Arachnoid villus Pia mater Arachnoid mater Dura mater Meningeal Periosteal Bone of skull Superior sagittal sinus Subdural space Subarachnoid space The Meninges • Dura mater – “Tough mother” – Strongest meninx – Fibrous connective tissue – Limit excessive movement of the brain – Forms partitions in the skull
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1/1/2016
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Meninges
CSF
The Nervous System
Introduction
• Protection of the brain
– Bone (skull)
– Membranes (meninges)
– Watery cushion (cerebrospinal fluid)
– Blood-brain barrier (astrocytes)
The Meninges
• Series of membranes
• Cover and protect the CNS
• Anchor and cushion the brain
• Contain cerebrospinal fluid (CSF)
The Meninges
• Three layers
– Dura mater
– Arachnoid mater
– Pia mater
Figure 12.24
Skin of scalp
Periosteum
Falx cerebri(in longitudinalfissure only)
Blood vesselArachnoid villusPia materArachnoid mater
Duramater Meningeal
Periosteal
Bone of skull
Superiorsagittal sinus
Subduralspace
Subarachnoidspace
The Meninges
• Dura mater – “Tough mother”
– Strongest meninx
– Fibrous connective tissue
– Limit excessive movement of the brain
– Forms partitions in the skull
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Figure 12.25a
Falx cerebri
Superior
sagittal sinus
Straight
sinus
Crista galliof theethmoid bone
Pituitary
gland
Falx
cerebelli
(a) Dural septa
Tentorium
cerebelli
The Meninges
• Arachnoid mater – “Spider mother”
– Middle layer with weblike extensions
– Separated from the dura mater by the subdural space
– Subarachnoid space contains CSF and blood vessels
The Meninges
• Pia mater – “Gentle mother”
– Connected to the dura mater by projections from
the arachnoid mater
– Layer of delicate vascularized connective tissue
Median apertureMedian apertureMedian apertureMedian aperture
(a) CSF circulation
CSF is produced by theCSF is produced by theCSF is produced by theCSF is produced by thechoroid plexus of eachchoroid plexus of eachchoroid plexus of eachchoroid plexus of eachventricle. ventricle. ventricle. ventricle.
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CSF flows through theCSF flows through theCSF flows through theCSF flows through theventricles and into the ventricles and into the ventricles and into the ventricles and into the subarachnoid space via the subarachnoid space via the subarachnoid space via the subarachnoid space via the median and lateral apertures. median and lateral apertures. median and lateral apertures. median and lateral apertures. Some CSF flows through the Some CSF flows through the Some CSF flows through the Some CSF flows through the central canal of the spinal cord.central canal of the spinal cord.central canal of the spinal cord.central canal of the spinal cord.
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CSF flows through theCSF flows through theCSF flows through theCSF flows through thesubarachnoid space. subarachnoid space. subarachnoid space. subarachnoid space.
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CSF is absorbed into the dural venousCSF is absorbed into the dural venousCSF is absorbed into the dural venousCSF is absorbed into the dural venoussinuses via the arachnoid villi. sinuses via the arachnoid villi. sinuses via the arachnoid villi. sinuses via the arachnoid villi.
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Cerebrospinal Fluid (CSF)
• Hydrocephalus
– Due to blockage or overproduction of CSF
– Internal hydrocephalus
• CSF accumulates in the ventricles, expanding them outward
– External hydrocephalus
• CSF accumulates in the subarachnoid space, compressing the
brain
Cerebrospinal Fluid (CSF)
• Hydrocephalus
– Due to blockage or overproduction of CSF
– Infants
• Head enlarges because skull bones have not yet fused
– Adults
• Accumulating fluid compresses blood vessels and soft
nervous tissue, causing brain damage
Cerebrospinal Fluid (CSF)
• Hydrocephalus
– Treatment
• 6/10 will die without treatment
• Shunts are placed to divert excess fluid to other areas of the