Lecture 2 (Meninges, ventricles, vascular supply, histology) Flashcards
The three membranes that surround and protect the brain and spinal cord are collectively called _
The three membranes that surround and protect the brain and spinal cord are collectively called meninges
Name 3 layers of meninges (deep to superficial)
- Pia mater: thin, fibrous inner layer that adheres to the brain and spinal cord
- Arachnoid mater: middle layer with web-like connections
- Dura mater: thick outer layer closest to the skull
Arachnoid mater is derived from [embryonic layer]
Arachnoid mater is derived from neural crest
Dura mater is derived from [embryonic layer]
Dura mater is derived from mesoderm
Pia mater is derived from [embryonic layer]
Pia mater is derived from neural crest
Leptomeninges = _ + _
Leptomeninges = arachnoid + pia
[Meninges layer] is derived from mesoderm
Dura mater is derived from mesoderm
The subarachnoid space is found between the arachnoid and _ layer
The subarachnoid space is found between the arachnoid and pia mater
The subarachnoid space contains _
The subarachnoid space contains CSF
The body produces about _ ml of CSF daily
The body produces about 500-1,000 ml of CSF daily
* Typical LP only takes about 28 ml or less
Excess CSF gets reabsorbed into the venous circulation via the [structure]
Excess CSF gets reabsorbed into the venous circulation via the arachnoid granulations
CSF returns to the venous circulation, specifically the _ via the arachnoid granulations
CSF returns to the venous circulation, specifically the dural venous sinus via the arachnoid granulations
Areas where the subarachnoid space enlarges are called _
Areas where the subarachnoid space enlarges are called cisterns
The largest cistern is the _
The largest cistern is the cerebellomedullary cistern
* AKA the cisterna magna
Name the cistern
Quadrigeminal cistern
CSF drains from the fourth ventricle to subarachnoid space through the lateral aperture,
CSF drains from the fourth ventricle to subarachnoid space through the lateral aperture, foramen of Luschka
CSF drains from the fourth ventricle to subarachnoid space through the medial aperture,
CSF drains from the fourth ventricle to subarachnoid space through the medial aperture, foramen of Magendie
The spinal cord ends at the level of _
The spinal cord ends at the level of L1-L2
Lumbar punctures are done between the level of _
Lumbar punctures are done between the level of L4-L5
As CSF travels from lateral ventricles –> third ventricle it passes through [foramen]
As CSF travels from lateral ventricles –> third ventricle it passes through intraventricular foramen
* AKA foramen of monro
CSF from the third ventricle flows through the [foramen] to reach the fourth ventricle
CSF from the third ventricle flows through the cerebral aqueduct (of sylvius) to reach the fourth ventricle
Step 1 of CSF production:
CSF is secreted by the _ in each lateral ventricle
CSF is secreted by the choroid plexus in each lateral ventricle
* Choroid plexus is a network of blood vessels and specialized cells in the ventricles (found in all ventricles)
Step 2 of CSF production:
After CSF is made by choroid plexus in the lateral ventricles, it flows through the interventricular foramina to the _
After CSF is made by choroid plexus in the lateral ventricles, it flows through the interventricular foramina to the third ventricle
Step 3 of CSF production
CSF has flown into third ventricle, next _
CSF has flown into third ventricle, next choroid plexus of the third ventricle adds more CSF
Step 4 of CSF production
From the third ventricle, the CSF flows to the fourth ventricle via the _
From the third ventricle, the CSF flows to the fourth ventricle via the cerebral aqueduct
Step 5 CSF production
Once CSF has reached the fourth ventricle, next _
Once CSF has reached the fourth ventricle, next choroid plexus in fourth ventricle adds more CSF
Step 6 CSF production
CSF leaves the fourth ventricle via _
CSF leaves the fourth ventricle via two lateral aperatures + one median aperature
Step 7 CSF production
What does CSF do after leaving the fourth ventricle?
CSF fills the subarachnoid space and bathes the external surfaces of the brain and spinal cord
Step 8 CSF production
CSF gets reabsorbed into the dural venous sinuses at _
CSF gets reabsorbed into the dural venous sinuses at arachnoid villi
* Rejoining venous blood
The blood brain barrier is the interface between [fluid] and [fluid]
The blood brain barrier is the interface between CSF and blood
Molecules like _ can pass the BBB freely, while _ require carrier transport
Molecules like H2O, O2, CO2 can pass the BBB freely, while glucose, H+, HCO3-, amino acids require carrier transport
The main location of CSF return via arachnoid granulations is to the _
The main location of CSF return via arachnoid granulations is to the superior sagittal sinus
Several veins, arteries, and nerves come together in the air filled cavity within the middle cranial fossa called the _
Several veins, arteries, and nerves come together in the air filled cavity within the middle cranial fossa called the cavernous sinus
The _ artery passes through the cavernous sinus (network of veins)
The internal carotid artery passes through the cavernous sinus (network of veins)
In addition to the internal carotid artery, [4 cranial nerves] also traverse the cavernous sinus
In addition to the internal carotid artery, oculomotor, trochlear, trigeminal (V1, V2), and abducens nerves also traverse the cavernous sinus
What are the manifestations of a thrombosis in the cavernous sinus?
- Dysfunctional eye movements: CN III, IV, VI
- Facial pain and numbness: CN V1, V2
- Eye swelling (venous congestion)
- Meningitis
The fold in dura mater that separates the two hemispheres is called the _ ; meanwhile the “tent” separating the temporal/occipital lobes from the cerebellum is the _
The fold in dura mater that separates the two hemispheres is called the falx cerebri ; meanwhile the “tent” separating the temporal/occipital lobes from the cerebellum is the tentorium cerebelli
The anteromedial surface of the brain is largely supplied by [artery]
The anteromedial surface of the brain is largely supplied by anterior cerebral artery (ACA)
The lateral surface of the brain is largely supplied by [artery]
The lateral surface of the brain is largely supplied by middle cerebral artery (MCA)
The posterior surface of the brain is largely supplied by [artery]
The posterior surface of the brain is largely supplied by posterior cerebral artery (PCA)
The inferior surface of the brain is largely supplied by [artery]
The inferior surface of the brain is largely supplied by posterior cerebral artery (PCA)
The anterior spinal artery originates from the two [arteries]
The anterior spinal artery originates from the two vertebral arteries
The [artery] is the only major arterial supply to the anterior spinal artery along the lower thoracic, lumbar, and sacral segments of the spinal cord
The artery of Adamkiewicz (AKA) is the only major arterial supply to the anterior spinal artery along the lower thoracic, lumbar, and sacral segments of the spinal cord
* T8-L1 at risk
_ is the location of the skull where 4 bones meet (frontal, parietal, temporal, sphenoid)
Pterion is the location of the skull where 4 bones meet (frontal, parietal, temporal, sphenoid)
The _ artery located at the temple is vulnerable to injury
The middle meningeal artery artery located at the temple is vulnerable to injury
Identify the purple region
Anterior cranial fossa
Identify the blue region
Middle cranial fossa
Identify the green region
Posterior cranial fossa
Name (3) foramen in the middle cranial fossa (anterior to posterior)
- Foramen rotundum
- Foramen ovale
- Foramen spinosum
ID the structure
Foramen magnum
The _ is an emetic reflex center at the floor of the fourth ventricle which lacks tight endothelial junctions
The area postrema is an emetic reflex center at the floor of the fourth ventricle which lacks tight endothelial junctions
A contralateral deficit of the face and arm is due to [artery] stroke
A contralateral deficit of the face and arm is due to an MCA stroke
A contralateral leg deficit is due to [artery] stroke
A contralateral leg deficit is due to ACA stroke
ID the structure
Vermis (cerebellum)
The cerebellum is about the same level as the [brainstem structure]
The cerebellum is about the same level as the pons
ID brainstem level
Midbrain
* Note the cerebral aqueduct
ID brainstem level
Pons
ID brainstem level
Medulla
* Note the inferior olivary nucleus
Cerebellar output is (excitatory/inhibitory)
Cerebellar output is inhibitory
Cerebellar output travels via [cells]
Cerebellar output travels via purkinje cells
Cerebellar input travels via [fibers]
Cerebellar input travels via mossy fibers
* Except for inferior olivary nuclei which travel via climbing fibers (fine motor control)
Cerebellar output tracts travels via [structure]
Cerebellar output tracts travels via superior cerebellar peduncles
Cerebellar input tracts travels via [structure]
Cerebellar input tracts travels via inferior cerebellar peduncles
The [cerebellar structure] is responsible for axial movements like center of gravity
The vermis is responsible for axial movements like center of gravity
[Lobe of cerebellum] integrates vestibular information to coordinate eye and head movement; lesions here can cause vertigo and nystagmus
Flocculonodular lobe integrates vestibular information to coordinate eye and head movement; lesions here can cause vertigo and nystagmus
Name the deep nuclei of the cerebellum from lateral to medial
- Dentate
- Emboliform
- Globose
- Fastigial
Don’t eat greasy food
[Deep cerebellar nucleus] is tasked with planning, initiating, and moderating voluntary movements
Dentate nucleus is tasked with planning, initiating, and moderating voluntary movements
* Especially distal precise movements like playing piano or writing
[Deep cerebellar nucleus] outputs to vestibular nuclei and brainstem regarding axial stability
Fastigial nucleus outputs to vestibular nuclei and brainstem regarding axial stability
* Particularly while walking or standing
[2 deep cerebellar nuclei] together send outputs performing proximal movement of limbs
Emboliform and globose nuclei together send outputs performing proximal movement of limbs
* Collectively called the interposed nuclei
What type of neuron resides in this region?
Pseudounipolar neuron: recall that dorsal horn has sensory neurons which are pseudounipolar
What is the function of these spider-shaped cells in the cerebral cortex?
Astrocytes: they establish the BBB
What is the function of the structure at the arrow?
Schwann cell: produces myelin
This structure is involved in the synthesis of what?
Nissl substance: the arrow is pointing to the nucleolus
* Nissl substance = RER
What are glial cells?
Glial cells are a category of cells that support and protect neurons
* Astrocytes, ependymal cells, microglia, oligodendrocytes, schwann cells, satellite cells
The arrow is pointed to the _ , which is lighter in appearance due to absence of _
The arrow is pointed to the axon hillock , which is lighter in appearance due to absence of RER, organelles
* Intermediate filaments from the axon are present here
Perikaryon is another name for [neuron region]
Perikaryon is another name for soma/ cell body
Microtubules are part of the cytoskeleton of the axon and are associated with two force-generating proteins called _ and _
Microtubules are part of the cytoskeleton of the axon and are associated with two force-generating proteins called dynein and kinesin
Anterograde movement is mediated by (dynein/ kinesin)
Anterograde movement is mediated by kinesin
* Antegrade means away from the cell body (+) end
Retrograde movement is mediated by (dynein/ kinesin)
Retrograde movement is mediated by dynein
* Retrograde means back towards cell body (-) end
Bipolar neurons are [type], found in [location]
Bipolar neurons are sensory, found in special sensory regions (retina, olfactory mucosa, inner ear)
Pseudounipolar neurons are [type], found in [location]
Pseudounipolar neurons are sensory, found in ganglia (cell bodies found in ganglia)
Multipolar neurons are [type], found in [location]
Multipolar neurons are motor, found in ventral horn
* Cell bodies are found in ventral horn of the spinal cord
_ is a layer of fibrous dense tissue (fascia) that forms the external coat of nerves
Epineurium is a layer of fibrous dense tissue (fascia) that forms the external coat of nerves
* Many fascicles are found within
_ surrounds each bundle of nerve fibers (fascicles)
Perineurium surrounds each bundle of nerve fibers (fascicles)
_ is the thin layer of reticular fibers (produced by schwann cells) that surrounds the individual nerve axons/fibers
Endoneurium is the thin layer of reticular fibers (produced by schwann cells) that surrounds the individual nerve axons/fibers
The perineurium’s inner layer contains flattened epitheloid cells that are joined by _ and form a _ barrier
The perineurium’s inner layer contains flattened epitheloid cells that are joined by tight junctions and form a blood-nerve barrier
* Prohibits passage of macromolecules
The cerebral cortex is divided into [#] layers; the layers containing _ cells are involved in the output of signals
The cerebral cortex is divided into 6 layers; the layers containing pyramidal cells are involved in the output of signals
* E.g. external pyramidal layer and internal pyramidal layer
* Pyramidal cell is the principal output neuron
[Cortical layers] are involved in intracortical connections
Cortical layers I-III are involved in intracortical connections
* Molecular/plexiform layer: horizontal connections between cortical areas
* External granular layer processing sensory info from other cortical areas
* External pyramidal layer output to parts of the cortex
[Cortical layers] are involved in connections to the thalamus
Cortical layers IV-VI are involved in connections to the thalamus
* Internal granular layer: receives sensory input from thalamus
* Internal pyramidal layer: sends output to the brainstem and spinal cord
* Multiform layer: sends output to thalamus
Small pyramidal cells can be found in [cortical layer]
Small pyramidal cells can be found in external granular layer (layer II)
The molecular/ plexiform layer of the cerebral cortex is largely made up of [cell type]
The molecular/ plexiform layer of the cerebral cortex is largely made up of neuroglia
Large pyramidal cells can be found in [2 cerebral cortex layers]
Large pyramidal cells can be found in external pyramidal layer and internal pyramidal layer
Stellate cells are a type of interneuron that are found primarily in [cortical layer]
Stellate cells are a type of interneuron that are found primarily in internal granular layer (IV)
ID the axon
Axon is not “fuzzy” like the dendritic spines
Name the (3) cell layers of the cerebellum (superficial to deep)
Name the (3) cell layers of the cerebellum
1. Molecular layer: stellate cells, basket cells, purkinje dendrites
2. Purkinje cell layer: purkinje cells
3. Granular layer: granule cells
Superficial –> deep, “MPG”
Type of neuron
Pyramidal
* Note that pyramidal cells are numerous in the cortex but not exclusive to the cortex; also in the hippocampus, amygdala, etc
Type of neuron
Purkinje
Purkinje cells are exclusive to the [brain region]
Purkinje cells are exclusive to the cerebellum
* Serve as the main output neurons of the cerebellar cortex, sending inhibitory signals to the deep cerebellar nuclei
_ is the largest of the neuroglial cells
Astrocyte is the largest of the neuroglial cells
[Neuroglial cells] have many processes and vascular feet to surround blood vessels and contact pia mater
Astrocytes have many processes and vascular feet to surround blood vessels and contact pia mater
* Communicate with one another via gap junctions
The shape of astrocytes is maintained by [protein] which is a marker for the cell
The shape of astrocytes is maintained by glial fibrillary acid protein (GFAP) which is a marker for the cell
Name the functions of astrocytes
Astrocyte functions:
1. Provide structural support
2. Aid metabolic transport (take up K+ and neurotransmitters)
3. Contribute to the BBB
4. Modulate blood flow
5. Cover axon at node of ranvier
6. Form scar tissue after CNS injury
[Astrocyte type] is mostly found in gray matter
Protoplasmic astrocyte is mostly found in gray matter
[Astrocyte type] is mostly found in white matter
Fibrous astrocyte is mostly found in white matter
The blood brain barrier is a [type] membrane between the blood and the interstitium of the brain
The blood brain barrier is a selective semi-permeable membrane between the blood and the interstitium of the brain
* Allows cerebral blood vessels to regulate molecule and ion movement between the blood and brain
The BBB is composed of [capillary type] and [astrocyte type]
The BBB is composed of continuous capillaries and protoplasmic astrocytes
* Continuous basement membrane, tight junctions, no fenestrations
_ is a membrane found between the pia mater and the nervous tissue of the brain/spinal cord
Glia limitans is a membrane found between the pia mater and the nervous tissue of the brain/spinal cord
* Astrocytes contribute to this sealed barrier
Oligodendrocytes are found in [location]
Oligodendrocytes are found in grey and white matter of CNS
* They produce the myelin for the CNS, electrical insulation for axons
Each oligodendrocyte produces myelin for [# axons]
Each oligodendrocyte produces myelin for many axons
ID these components
_ are small phagocytic cells, aka “macrophages of the CNS”
Microglia are small phagocytic cells, aka “macrophages of the CNS”
Microglia are derived from [progenitor cells]
Microglia are derived from mononuclear cells in the bone marrow
Activated microglial cells become antigen-presenting cells and secrete _
Activated microglial cells become antigen-presenting cells and secrete cytokines
* Cytokines are toxic to neurons; AIDS patients have large population of microglial cells
[Neural cells] line the neural tube in the embryo, ventricles of the brain, and central canal of the spinal cord
Ependymal cells line the neural tube in the embryo, ventricles of the brain, and central canal of the spinal cord
[Cells] assist the [structure] in producing CSF
Ependymal cells assist the choroid plexus in producing CSF
* Modified ependymal cells contribute to the formation of the choroid plexus which forms the CSF in the ventricles of the brain
Ependymal cells can possess [structure] to help move CSF
Ependymal cells can possess cilia to help move CSF
_ cells produce the endoneurium (connective tissue surrounding a neuron) in the PNS
Schwann cells cells produce the endoneurium (connective tissue surrounding a neuron) in the PNS
* Can also form unmyelinated coverings for neurons (axons that are not fully wrapped)
A single Schwann cell insulates [# axons] in the PNS
A single Schwann cell insulates only one single axon in the PNS
The myelin sheath is not continuous along the length of the axon; it is interrupted by gaps called _
The myelin sheath is not continuous along the length of the axon; it is interrupted by gaps called nodes of Ranvier
In the CNS, the nodes of Ranvier are covered by _
In the CNS, the nodes of Ranvier are covered by a foot plate of an astrocyte
In the PNS, the nodes of Ranvier are covered by _
In the PNS, the nodes of Ranvier are covered by interdigitated cytoplasmic processes of adjacent Schwann cells
ID the components
_ and _ neurons are heavily myelinated
Multipolar and pseudounipolar neurons are heavily myelinated
* Meaning the axon is fully wrapped many times
Preganglionic neurons in the autonomic nervous system are (heavily/lightly/un-) myelinated
Preganglionic neurons in the autonomic nervous system are lightly myelinated
Name some neurons that are unmyelinated
Unmyelinated neurons include:
* Visceral sensory neurons
* Postganglionic neurons of ANS
* Some types of pain fibers
[Neural cells] are found around the perimeter of neuron cell bodies in ganglia (PNS)
Satellite cells are found around the perimeter of neuron cell bodies in ganglia (PNS)
The function of satellite cells is to _
The function of satellite cells is to provide structural and nutritional support to neuron cell bodies (kind of similar to astrocytes but in the PNS)
Satellite cells are found surrounding the neuron cell bodies in _ and _ ganglia
Satellite cells are found surrounding the neuron cell bodies in sensory and autonomic ganglia
ID the cell type
Satellite cells
How are satellite cells in autonomic ganglia different from sensory ganglia?
- Irregular in shape (less round)
- Farther apart
- Fewer, making room for synapses
CNS tumors are more commonly associated with (neurons/glial cells)
CNS tumors are more commonly associated with glial cells
Injury to the axon involves chromatolysis of cell body which means _
Injury to the axon involves chromatolysis of cell body which means fewer nissl bodies + loss of basophilia
* Cell body will increase in volume and push nucleus to periphery
* Myelin will degenerate and muscle can atrophy
Repair of an injured neuron involves proliferation of [cell]
Repair of an injured neuron involves proliferation of Schwann cells
* Also see regeneration of axon and muscle
What brain region are we in?
purkinje cells = Cerebellum
Type of cell
Purkinje
Ependymal cells
Microglia
What are the wavy blue streaks
Schwann cell nuclei
