Histology of the CNS Flashcards
1
Q
Examples of Integrative Neurons
A
- Pyramidal cells
- Interneurons
- Purkinje cells
2
Q
Neuropil
A
Dense network of interwoven nerve fibers, their branches and synapses, together with glial processes
3
Q
Central masses of gray matter:
A
Ventral, dorsal, and lateral horns
4
Q
__ __ lies in the Central Commissure of gray matter
A
Central Canal
5
Q
White matter consists of:
A
- Ascending tracts of sensory fibers
- Descending motor tracts
6
Q
Motor neurons found in __ horn
A
Ventral
7
Q
Sensory neurons found in ___ horn
A
Dorsal
8
Q
Lateral corticospinal tract is associated with:
A
Motor control
9
Q
Anterolateral system is associated with:
A
Pain and temperature information
10
Q
Blood supply to UE and Thoracic part of Lateral Corticospinal Tract:
A
Sulcal A (branch of Anterior Spinal A)
11
Q
Blood supply to LE part of Lateral Corticospinal Tract:
A
Arterial Vasocorona (AVC)
12
Q
Blood supply to Anterolateral system:
A
Arterial Vasocorona (AVC)
13
Q
Arterial Vasocorona (AVC)
A
- Vascular Plexus that is formed between the Posterior and Anterior Spinal Arteries
- Formed around the posterior roots of the spinal nerves
14
Q
Blood supply to the Fasciculus Cuneatus and Fasciculus Gracilis:
A
Posterior Spinal A (specifically the AVC)
15
Q
The brainstem is the passageway for __ and ___ fiber tracts
A
Afferent and Efferent
16
Q
CN Nuclei in the Brainstem: Sensory fibers are ___ to motor fibers
A
Lateral
17
Q
CN Nuclei in the Brainstem: Motor fibers are ___ to sensory fibers
A
Medial
18
Q
CN that emerge from the Medulla:
A
- CN IX
- CN X
- CN XI
- CN XII
19
Q
CN that emerge from the Pons:
A
- CN V
- CN VI
- CN VII
- CN VIII
20
Q
CN that emerge from the Midbrain:
A
- CN III
- CN IV
21
Q
CN that emerge outside of the brainstem:
A
- CN I
- CN II
22
Q
Cranial Nerve Nuclei follow a __-____ pattern arising from the alar and basal plates
A
Medial-Lateral
23
Q
Indication of brainstem problem
A
Vertigo or diplopia PLUS weakness/sensory disturbance in limbs/face
24
Q
4 Structures that are found in the Paramedian Brainstem:
A
(1) Motor pathway
(2) Medial Lemnisci
(3) Motor Nuclei
(4) Motor Longitudional Fasciculus
25
4 CN Nuclei that lie in the Paramedian Brainstem:
- CN III
- CN IV
- CN VI
- CN XII
26
4 Structures that are found in the Lateral Brainstem:
(1) Spinothalamic Pathway
(2) Sympathetic Pathway
(3) Sensory Nucleus of CN V
(4) Spinocerebellar Tract
27
CN Nuclei found in the Midbrain:
- CN III
- CN IV
28
CN Nuclei found in the Pons:
- CN VI
- CN VII (Superior Salivatory Nucelus, Motor Nucleus)
29
CN Nuclei found in the Medulla:
- CN VII (Nucleus Solitarius)
- CN VIII
- CN IX
- CN X
30
Substantia Nigra
- Gray matter substance within the midbrain
- Contains pigmented multipolar neurons
31
Function of Substantia Nigra
- Connections with cortex, spinal cord, corpus striatum, and reticular formation
- Role in fine control of motor function
32
Characteristics of neurons in the Substantia Nigra
- Contain numerous membrane-bound granules of neuromelanin pigment
- Neuromelanin contains dopamine which has inhibitory effects in brain areas dedicated to movement
33
Parkinson's Disease
- Clinical features: tremor, slow movement, rigidity
- Results from degeneration of neurons in the substantia nigra (results in loss of dopamine)
- Distinctive inclusions seen in remaining neurons -- Lewy Bodies
- Aggregates of alpha-synuclein and other proteins
34
Neocortex consists of __ layers
6
35
What are the 6 layers of the Cerebral Cortex?
Superficial (just under Pia Mater) --> Deep
(1) Molecular
(2) External Granular
(3) External Pyramidal
(4) Inner Granular
(5) Ganglionic
(6) Multiform (Polymorphic)
36
Cerebral Cortex: Molecular Layer
Contains large fibers and neuroglial cells
37
Cerebral Cortex: External Granular Layer
Contains small pyramidal cells and granule (stellate) cells
38
Cerebral Cortex: External Pyramidal Layer
Contains larger pyramidal cells with a typical pyramidal shape
39
Cerebral Cortex: Inner Granular Layer
Contains many small granule (stellate) cells
40
Cerebral Cortex: Ganglionic Layer
Contains extra-large pyramidal cells -- called Betz Cells in motor areas like the motor cortex
41
Cerebral Cortex: Multiform (Polymorphic) Layer
Contains cells with a variety of shapes
42
Alzheimer Disease
- Most common neurodegenerative disease
- Incidence increases with age (avg age is 70+)
- Etiology unknown -- small portion has genetic association
43
Symptoms of Alzheimer's Disease
- Memory failure
- Progressing steadily to involved motor skills, speech and sensation
44
In Alzheimer's Disease, there is thinning of the gyri, particularly those of the __ and __ lobes
Frontal and Temporal
45
Histology of Alzheimer's Disease
Amyloid Plaques, neurofibrillary tangles and neuronal loss are identified on sections
46
Amyloid-Beta Plaques
Amorphous, pink masses in the cortex
47
Neurofibrillary Tangles
Flame-shaped skeins formed by abnormal accumulation of tau (protein)
48
What are the 3 layers of the Cerebellar Cortex?
(1) Molecular
(2) Purkinje Cells
(3) Granular
49
Cerebellar Cortex: Molecular Layer
- Outermost layer
- Contains Neuropil and scattered neuronal cell bodies
50
Cerebellar Cortex: Purkinje Cells
- Middle layer
- Only one cell layer thick
- Extend dendrites throughout the molecular layer as a branching basket of nerve fibers
51
Cerebellar Cortex: Granular Layer
- Innermost layer
- Contains various very small densely packed neurons (i.e granule cells) and little neuropil
52
Cerebellar Cortex is organized into folia with the ___ ___ located deep
Cerebellar Medulla
** not considered layer of cortex!
53
Meninges
- Protect the CNS from the skull and vertebral column
- Consists of Dura Mater, Arachnoid Mater, and Pia Mater
54
Dura Mater
Thick layer of connective tissue
55
Arachnoid Mater
- Delicate sheet of connective tissue adjacent to the inner surface of the dura, covered with a thin squamous epithelial layer
- Avascular (lacks nutritive capillaries), but blood vessels do run through it
56
What structure extends from the Arachnoid Mater to the Pia Mater of the brain and SC?
Arachnoid Trabeculae
57
ARachnoid Villi
- Areas where arachnoid mater penetrates the dura mater and protrudes into dural venous sinuses
- Covered by the vascular endothelial cells
- Function as sites for absorption of CSF into the blood of the venous sinuses
58
Pia Mater
- Lies directly on the surface of the brain and SC
- Covered with thin squamous epithelial layer
59
Astrocytes: Structure
- Contain a large number of long, branching processes
- Proximal regions are reinforced with intermediate filaments made of Glial Fibrillary Acid Protein (GFAP)
60
Astrocytes
- Form a vast network of delicate terminals contacting synapses and other structures
- Terminal processes of a single astrocyte can associate with 1M+ synaptic sites
61
TBlood Brain Barrier
Protects CNS from electrolytes, hormones and metabolites in the blood
62
What forms the Blood Brain Barrier?
Tight Junctions between:
- Endothelial cells of continuous capillaries
- Astrocyte end foot processes with basal lamina of endothelial cells
63
Function of Tight Junctions
Eliminate gaps between endothelial cells and prevent simple diffusion to surrounding brain tissue
64
Ependymal Cells
- Columnar or cuboidal cells that line the brain ventricles and the central canal of the spinal cord
- Apical end may have cilia and long microvilli which facilitate movement of CSF and help with absorption
- Joined apically by apical junctional complexes
65
Do Ependymal Cells have a basal lamina?
No
66
Choroid Plexus: Location
- Roofs of the 3rd and 4th ventricles, and parts of the lateral ventricular walls
- Completely fills ventricles, central canal of SC, subarachnoid and perivascular spaces
67
Choroid Plexus: Structure
Thin, elaborated folded layer of well-vascularized pia mater covered by cuboidal ependymal cells
68
Function of Choroid Plexus
Removes H2O from blood and releases it as CSF
69
Function of Choroid Plexus
Removes H2O from blood and releases it as CSF
70
What is found in the Choroid Plexus?
- Contains very Na+, K+, and Cl- ions
- Very little protein
- Only cells include sparse lymphocytes
71
Arachnoid Villi provide absorption pathway for ___ back into the venous circulation
CSF
72
Choroid Plexus
- Branching system of blood vessels which run in fronts composed of a fibrous core covered by cuboidal/columnar epithelium --> villous structure
- Capillaries and vessels are large and have thin walls
- Epithelial cells rest on a basal lamina
- Long bulbous microvilli project from the epithelial cells
73
What contributes to the blood-CSF barrier?
Tight junctions (Zonula Occludens) between epithelial cells
74
Circumventricular Organs
- Areas of the CNS that are not isolated from substances carried in the bloodstream
- Function in sampling materials circulating in the blood that are normally excluded by the blood-brain barrier -- convey information to CNS
- Important in regulating body fluid homeostasis and controlling neurosecretory activity of the nervous system
75
Circumventricular Organs
- Pineal Gland
- Median Eminence
- Area Postrema
- Posterior lobe of Pituitary Gland
76
Brain Lymphatic Drainage System is composed of:
- Basement membrane-based perivascular pathway
- Brain-wide glymphatic pathway
- CSF drainage routes
77
Drainage route for ISF from brain tissue to nearby lymph nodes:
(1) Helps maintain water and ion balance of the ISF, waste clearance and reabsorption of macromolecular solutes
(2) Communicates with immune system to modulate immune surveillance and responses of the brain
78
Glial Cell: Oligodendrocyte
(1) Origin
(2) Location
(3) Main Functions
(1) Neural tube
(2) CNS
(3) Meylin production, electrical insulation
- Enwrap axons from multiple neurons
- A single axon may be enwrapped by many oligodendrocytes
- Histology: appear as small cells with rounded, condensed nuclei and unstained cytoplasm
79
Glial Cell: Astrocyte
(1) Origin
(2) Location
(3) Main Functions
(1) Neural Tube
(2) CNS
(3) Structural and metabolic support of neurons, especially at synapses; repair processes
80
Glial Cell: Ependymal Cell
(1) Origin
(2) Location
(3) Main Functions
(1) Neural Tube
(2) Line ventricles and central canal of CNS
(3) Aid in production and movement of CSF
81
Glial Cell: Microglia
(1) Origin
(2) Location
(3) Main Functions
(1) Bone marrow (monocytes)
(2) CNS
(3) Defense and immune-related activites
82
Describe "Perikarya"
- Term used to describe the nucleus of a neuron
- Euchromatic with a prominent nucleolus
83
What is the functional classification of somatic neurons?
- Participate in the control of skeletal muscles
- Relay motor (NOT SENSORY) information from the body
84
Tiny structures located along dendrites that are functionally implicated in learning and memory:
Dendritic Spines
- Create plasticity
85
What glial cell is responsible for providing structural and metabolic support to ganglia throughout the body?
Satellite Cells
86
Pyramidal cells can best be visualized in which layer of the cerebrum?
Ganglionic Layer
87
Layers of Cerebellum from most superficial to deepest:
(1) Molecular Layer
(2) Granular Layer
(3) Medulla
88
What is unique about brain nuclei?
They are pockets of gray matter structures buried in white matter
89
Description of the word "cortex"
The arrangement of neurons over the surface of the brain
90
Sections of the spinal cord are wider/larger in the cervical and thoracic regions. What is the purpose of this change?
They are wider in these regions because of the cervical and lumbar enlargements; the increased size is a result of larger amounts of gray and white matter needed to control the limbs
91
What brain region/structure are Purkinje Cells found in?
Cerebellar Cortex
- use their dendritic trees to gather information from synapses arising from parallel fibers and climbing fibers
92
Neurons that utilize dopamine are particularly abundant in the:
Substantia Nigra of the Midbrain
93
Structure surrounding the bundle of axons in a peripheral nerve that forms a non-permeable barrier between the blood and the nerve:
Perineurium
- composed of fibroblast-like cells that exhibit tight junctions between themselves; these junctions form a barrier to exchange of fluid between nervous tissue and surrounding tissues
94
Most important function of Neurolemmocytes:
Form myelin
95
Location of Nodes of Ranvier:
Between adjacent Neurolemmocytes in a peripheral nerve
96
What are the only output neurons of the cerebellum?
Purkinje Neurons
