Lecture 2 (Meninges, ventricles, vascular supply, histology) Flashcards
(147 cards)
1
Q
The three membranes that surround and protect the brain and spinal cord are collectively called _
A
The three membranes that surround and protect the brain and spinal cord are collectively called meninges
2
Q
Name 3 layers of meninges (deep to superficial)
A
- 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
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Q
Arachnoid mater is derived from [embryonic layer]
A
Arachnoid mater is derived from neural crest
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Q
Dura mater is derived from [embryonic layer]
A
Dura mater is derived from mesoderm
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Q
Pia mater is derived from [embryonic layer]
A
Pia mater is derived from neural crest
5
Q
Leptomeninges = _ + _
A
Leptomeninges = arachnoid + pia
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Q
[Meninges layer] is derived from mesoderm
A
Dura mater is derived from mesoderm
7
Q
The subarachnoid space is found between the arachnoid and _ layer
A
The subarachnoid space is found between the arachnoid and pia mater
8
Q
The subarachnoid space contains _
A
The subarachnoid space contains CSF
9
Q
The body produces about _ ml of CSF daily
A
The body produces about 500-1,000 ml of CSF daily
* Typical LP only takes about 28 ml or less
10
Q
Excess CSF gets reabsorbed into the venous circulation via the [structure]
A
Excess CSF gets reabsorbed into the venous circulation via the arachnoid granulations
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Q
CSF returns to the venous circulation, specifically the _ via the arachnoid granulations
A
CSF returns to the venous circulation, specifically the dural venous sinus via the arachnoid granulations
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Q
Areas where the subarachnoid space enlarges are called _
A
Areas where the subarachnoid space enlarges are called cisterns
13
Q
The largest cistern is the _
A
The largest cistern is the cerebellomedullary cistern
* AKA the cisterna magna
14
Q
Name the cistern
A
Quadrigeminal cistern
15
Q
CSF drains from the fourth ventricle to subarachnoid space through the lateral aperture,
A
CSF drains from the fourth ventricle to subarachnoid space through the lateral aperture, foramen of Luschka
16
Q
CSF drains from the fourth ventricle to subarachnoid space through the medial aperture,
A
CSF drains from the fourth ventricle to subarachnoid space through the medial aperture, foramen of Magendie
17
Q
The spinal cord ends at the level of _
A
The spinal cord ends at the level of L1-L2
18
Q
Lumbar punctures are done between the level of _
A
Lumbar punctures are done between the level of L4-L5
19
Q
As CSF travels from lateral ventricles –> third ventricle it passes through [foramen]
A
As CSF travels from lateral ventricles –> third ventricle it passes through intraventricular foramen
* AKA foramen of monro
20
Q
CSF from the third ventricle flows through the [foramen] to reach the fourth ventricle
A
CSF from the third ventricle flows through the cerebral aqueduct (of sylvius) to reach the fourth ventricle
21
Q
Step 1 of CSF production:
CSF is secreted by the _ in each lateral ventricle
A
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)
22
Q
Step 2 of CSF production:
After CSF is made by choroid plexus in the lateral ventricles, it flows through the interventricular foramina to the _
A
After CSF is made by choroid plexus in the lateral ventricles, it flows through the interventricular foramina to the third ventricle
23
Q
Step 3 of CSF production
CSF has flown into third ventricle, next _
A
CSF has flown into third ventricle, next choroid plexus of the third ventricle adds more CSF
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# 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**
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# 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**
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# Step 6 CSF production
CSF leaves the fourth ventricle via _
CSF leaves the fourth ventricle via **two lateral aperatures + one median aperature**
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# 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
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# 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*
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The blood brain barrier is the interface between [fluid] and [fluid]
The blood brain barrier is the interface between **CSF** and **blood**
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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
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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**
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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**
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The _ artery passes through the cavernous sinus (network of veins)
The **internal carotid artery** passes through the cavernous sinus (network of veins)
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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
35
What are the manifestations of a thrombosis in the cavernous sinus?
1. **Dysfunctional eye movements**: CN III, IV, VI
2. **Facial pain and numbness**: CN V1, V2
3. Eye swelling (venous congestion)
4. Meningitis
36
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**
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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)**
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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)**
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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)**
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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)**
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The anterior spinal artery originates from the two [arteries]
The anterior spinal artery originates from the two **vertebral arteries**
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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*
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_ 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)
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The _ artery located at the temple is vulnerable to injury
The **middle meningeal artery** artery located at the temple is vulnerable to injury
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Identify the purple region
**Anterior cranial fossa**
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Identify the blue region
**Middle cranial fossa**
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Identify the green region
**Posterior cranial fossa**
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Name (3) foramen in the middle cranial fossa (anterior to posterior)
1. **Foramen rotundum**
2. **Foramen ovale**
3. **Foramen spinosum**
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ID the structure
**Foramen magnum**
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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
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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
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A contralateral leg deficit is due to [artery] stroke
A contralateral leg deficit is due to **ACA** stroke
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ID the structure
**Vermis** (cerebellum)
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The cerebellum is about the same level as the [brainstem structure]
The cerebellum is about the same level as the **pons**
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ID brainstem level
Midbrain
* *Note the cerebral aqueduct*
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ID brainstem level
Pons
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ID brainstem level
Medulla
* *Note the inferior olivary nucleus*
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Cerebellar output is (excitatory/inhibitory)
Cerebellar output is **inhibitory**
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Cerebellar output travels via [cells]
Cerebellar output travels via **purkinje cells**
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Cerebellar input travels via [fibers]
Cerebellar input travels via **mossy fibers**
* *Except for inferior olivary nuclei which travel via climbing fibers (fine motor control)*
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Cerebellar output tracts travels via [structure]
Cerebellar output tracts travels via **superior cerebellar peduncles**
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Cerebellar input tracts travels via [structure]
Cerebellar input tracts travels via **inferior cerebellar peduncles**
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The [cerebellar structure] is responsible for axial movements like center of gravity
The **vermis** is responsible for axial movements like center of gravity
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[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
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Name the deep nuclei of the cerebellum from lateral to medial
1. **Dentate**
2. **Emboliform**
3. **Globose**
4. **Fastigial**
*Don't eat greasy food*
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[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*
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[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*
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[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*
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What type of neuron resides in this region?
**Pseudounipolar neuron**: recall that dorsal horn has sensory neurons which are pseudounipolar
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What is the function of these spider-shaped cells in the cerebral cortex?
**Astrocytes**: they establish the BBB
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What is the function of the structure at the arrow?
**Schwann cell**: produces myelin
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This structure is involved in the synthesis of what?
**Nissl substance**: the arrow is pointing to the nucleolus
* *Nissl substance = RER*
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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*
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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*
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Perikaryon is another name for [neuron region]
Perikaryon is another name for **soma/ cell body**
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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**
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Anterograde movement is mediated by (dynein/ kinesin)
Anterograde movement is mediated by **kinesin**
* *Antegrade means away from the cell body (+) end*
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Retrograde movement is mediated by (dynein/ kinesin)
Retrograde movement is mediated by **dynein**
* *Retrograde means back towards cell body (-) end*
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Bipolar neurons are [type], found in [location]
Bipolar neurons are **sensory**, found in **special sensory regions (retina, olfactory mucosa, inner ear)**
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Pseudounipolar neurons are [type], found in [location]
Pseudounipolar neurons are **sensory**, found in **ganglia** (cell bodies found in ganglia)
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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*
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_ 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*
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_ surrounds each bundle of nerve fibers (fascicles)
**Perineurium** surrounds each bundle of nerve fibers (fascicles)
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_ 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
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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
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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*
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[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
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[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
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Small pyramidal cells can be found in [cortical layer]
Small pyramidal cells can be found in **external granular layer (layer II)**
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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**
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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**
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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)**
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ID the axon
Axon is not "fuzzy" like the dendritic spines
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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"*
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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*
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Type of neuron
Purkinje
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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*
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_ is the largest of the neuroglial cells
**Astrocyte** is the largest of the neuroglial cells
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[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*
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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
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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**
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[Astrocyte type] is mostly found in gray matter
**Protoplasmic astrocyte** is mostly found in gray matter
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[Astrocyte type] is mostly found in white matter
**Fibrous astrocyte** is mostly found in white matter
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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
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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*
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_ 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*
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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*
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Each oligodendrocyte produces myelin for [# axons]
Each oligodendrocyte produces myelin for ***many axons***
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ID these components
118
_ are small phagocytic cells, aka "macrophages of the CNS"
**Microglia** are small phagocytic cells, aka "macrophages of the CNS"
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Microglia are derived from [progenitor cells]
Microglia are derived from **mononuclear cells in the bone marrow**
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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
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[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
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[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*
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Ependymal cells can possess [structure] to help move CSF
Ependymal cells can possess **cilia** to help move CSF
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_ 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)*
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A single Schwann cell insulates [# axons] in the PNS
A single Schwann cell insulates ***only one single axon*** in the PNS
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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**
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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**
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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**
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ID the components
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_ and _ neurons are heavily myelinated
**Multipolar** and **pseudounipolar** neurons are heavily myelinated
* *Meaning the axon is fully wrapped many times*
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Preganglionic neurons in the autonomic nervous system are (heavily/lightly/un-) myelinated
Preganglionic neurons in the autonomic nervous system are **lightly myelinated**
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Name some neurons that are unmyelinated
*Unmyelinated* neurons include:
* **Visceral sensory** neurons
* **Postganglionic** neurons of ANS
* Some types of pain fibers
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[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)
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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)
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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
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ID the cell type
Satellite cells
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How are satellite cells in autonomic ganglia different from sensory ganglia?
* Irregular in shape (less round)
* Farther apart
* Fewer, making room for synapses
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CNS tumors are more commonly associated with (neurons/glial cells)
CNS tumors are more commonly associated with **glial cells**
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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
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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
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What brain region are we in?
purkinje cells = **Cerebellum**
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Type of cell
Purkinje
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Ependymal cells
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Microglia
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What are the wavy blue streaks
Schwann cell nuclei
