Nervous System Flashcards
1
Q
What is the CNS composed of? Where are these located?
A
- brain (cranial cavity)
- spinal chord (vertebral canal)
2
Q
What protects the skull and vertebra? What is it called? How many layers is it composed of?
A
MENINGES:
- 3 connective tissue membranes
3
Q
What does the brain and spinal chord ‘float’ in? Where is it located?
A
cerebrospinal fluid
- occupies the space between the two inner meningeal layers
4
Q
What is the brain further subdivided into?
A
cerebrum, cerebellum and the brain stem (connects to the spinal chord)
5
Q
What is the function of the cerebellum? Where is it located?
A
- back of head
- movement and balance
6
Q
What is the ‘gray matter’ of the brain? What does it include? What is its function?
A
Gray matter=cerebral cortex (outside)
- forms the outermost layer of the brain
- form “nuclei” found in deep portions of the cerebrum and cerebellum
- consists of: nerve cell bodies, axons, dendrites, central glial cells
- site of synapses
7
Q
What is the brain made up of?
A
- neurons
- high concentration
8
Q
What causes the colour of the brain to differ (white vs gray matter)?
A
- made up of the same thing
- different parts of neurons
9
Q
What makes the gray matter darker?
A
- high concentrations of the body’s of neurons
10
Q
What makes the gray matter darker?
A
high concentration of neuron processes (dendrites and axons)
11
Q
What types of cell bodies are found in the gray matter of the brain? What is the collective name for the cell bodies?
A
- characteristic variety of cell bodies
NEUROPIL - meshwork of axonal, dendritic and glial processes
12
Q
State the composition of white matter.
A
- axons of nerve cells (fresh=white)
- associated glial cells and blood vessels
(axons of nerve cells are traveling from one part of the NS to another)
13
Q
What is the name of the functionally related bundles to which axons are going to or coming from?
A
tracts
14
Q
Do tracts stand out as delinated bundles?
A
no!
15
Q
What is located in both white and gray matter?
A
supportive glial cells
16
Q
What is an additional structure located in white matter?
A
tracts
17
Q
Can tracts be seen? How are they formed?
A
no!
- mostrly hypothetical
- do not have any distinct feautures
- form due to memorization (same action repeated many times)
18
Q
How many layers is the cerebral cortex divided into?
A
6 layers
19
Q
What are the 6 layers of the cerebral cortex?
A
1) molecular layer
2) external granular layer
3) external pytamidal layer
4) internal granular layer
5) internal pyramidal layer
6) fusiform (multiform) layer
20
Q
State the composition of the molecular layer of the cerebral cortex.
A
- neutropil-oriented tangentially
- apical dendrites from pyramidal cells
- terminal branches of superficial cortical afferent fibers
neuropil= no neuron bodies, only their processes
21
Q
State the composition of the external granular layer of the cerebral cortex.
A
- SMALL neurons that serve as interneurons (SMALL %)
granular= small neurons (SMALL %)
interneurons= connects molecular&deep
22
Q
State the composition of the external pyramidal layer of the cerebral cortex.
A
- small and medium pyramidal neurons
- send axons to adjacent cerebral cortex
pyramidal shape,
23
Q
State the composition of the internal granular layer of the cerebral cortex.
A
- small stellate neurons
- recieve specific sensory input
- thick layer in sensory areas of the cortex (eg. primary visual area)
24
Q
State the composition of the internal pyramidal layer of the cerebral cortex.
A
- medium to large pyramidal neurons
- send axons to the white matter
- thick layer in the motor area of the cortex
LARGER pyramids
25
State the composition of the fusiform (multiform) layer of the cerebral cortex.
- many spindle shaped neurons
- send axons into the white matter
- deep to this layer, the cerebral white matter is composed of nerve fibers going to and coming from the cortex.
| SPINDLE SHAPED
26
How many layers is the cerebellar cortex divided into?
3 layers
27
What are the 3 layers of the cerebral cortex?
1) molecular layer
2) granule cell layer
3) piriform cell layer (purkinje cell layer)
28
State the composition of the molecular layer of the cerebellar cortex.
- neuropil
- only nerve processes (no neurons)
- most superficial
29
State the composition of the granule cell layer of the cerebellar cortex.
- adjacent to the white matter
- DENSELY packed granule cells (SMALL NEURONS)
30
How does the graular cell layer of the cerebellum compare with the cerebrum?
cerebellum= densely packaged= 5x more neurons
31
State the composition of the piriform cell layer of the cerebellar cortex. What is its other name? Where is it located?
piriform layer= purkinje cell layer
- **single** layer of LARGE **cell bodies**
- located at the **interface** of the molecular and granule cell layers
| very small SINGLE layer but BIG cells
32
How many layers is the brain stem divided into?
- NOT clearly seperated into regions of gray and white matter
33
What is visible throughout the structure of the brain stem?
**Nuclei** of *cranial nerves*:
- appear in **islands**
- surrounded by distinct tracts of **white matter**
34
State the composition of the nuclei of the brain stem.
- contain cell bodies of motor neurons (of cranial nerves)
- morphologic and functional counterparts of the anterior horns of the spinal chord
35
How are neurons oriented in the lower part of the brain stem?
white matter is oriented:
- transversely
- longitudinally
and is intermixed with gray matter with faintly prominent neurons.
36
Why is the spinal chord important?
nerves go through the spinal chord
- protects nerves
- provides a distinct tract
37
What is the spinal chord?
a flattened cylindrical structure that is directly continuous with the brain stem
38
State the organization of the spinal chord.
- divided into **segments**
- segments are connected to pairs of **spinal nerves**
- spinal nerves are connected to its segment of the cord by a number of rootlets grouped as **dorsal** (posterior) or **ventral** (anterior) **roots**.
39
What are ganglions?
- part of PNS
- bodies of neurons are concenrated in this area
40
Where are body neurons concentrated?
- CNS: gray matter
- PNS: ganglions
41
Explain the visual anatomy of the spinal chord.
- opposite arrangement of gray and white matter: gray interior, white exterior
- the gray-matter surrounds the central canal
- the white matter surrounds the gray matter (peripheral substance)
42
What does the white matter of the spinal chord contain?
tracks of **myelinated** and **unmyelinated** **axons** traveling:
- to and from other parts of the spinal chord
- to and from the brain
43
What does the gray matter of the spinal chord contain?
- neuronal cell **bodies**
- neuronal cell **dendrites**
- neuronal cell **axons**
- central **neuroglia**
44
What are "nuclei"?
Functionally related groups of nerve cell bodies in the gray matter.
- nucleus= cluster/group of neuronal cell bodies, fibers and neuroglia
45
Compare the nuclei of the CNS and PNS.
nuclei of the CNS are the morphologic and functional equivalents of the ganglia of the PNS.
46
What only occurs in the gray matter of the spinal chord?
synapses
47
What is the major difference between the gray matter in the brain and spinal chord?
Spinal chord doesn't have layers like the molecular, pyramidal or granular layers found in the brain.
48
How is the spinal cord divided into layers? What are they?
anatomically divided into sections:
- dorsal horn
- intermediate gray
- ventral horn
49
Where are sensory neuron cell bodies located in the spinal nerve?
In GANGLIA which lie on the dorsal root of the spinal nerve.
50
State the polarity of sensory neurons in the dorsal root ganglia.
pseudounipolar
51
Explain the polarity of sensory neurons in the dorsal root ganglia.
psudounipolar:
- **single process**
- divides into a **peripheral segment** (brings information from the periphery to the cell body)
- divides into a **central segment** (brings information from the cell body to the gray matter of the spinal chord)
52
Where are the cell bodies of motor neurons that innerviate striated muscles located?
In the **ventral** (anterior) **horn** of the **gray matter**.
53
What are ventral motor neurons? Other name?
- ventral motor neurons = anterior horn cells
- large, basophyllic cells
- easily reorganized in routine histologic preparations
54
Do motor neurons have direct connection to sensory nerves?
**no**!
- no direct connection
- connected by **interneurons** (bipolar neurons- 1 axon, 1 dentrite)
55
What connective tissue is present in the CNS?
**Meninges**: connective tissue membranes covering the brain and spinal chord
- **dura mater** (outermost)
- **arachnoid** (middle)
- **pia mater** (directly on the surface if the brain and spinal chord)
56
What two layers have a very similar developmental patter? What is it? What does this lead to?
- arachnoid and pia mater
- called by 1 name: pia-arachnoid
- single layer of mesenchyme surrounding the developing brain
57
State the portions in adults of which the pia mater and arachnoid occupy.
pia mater: visceral portion
arachnoid: parietal portion
58
What is the location of the arachnoid? What structures does it have?
- abuts on the **inner surface** of the dura mater
- extends delicate ***arachnoid tubercules*** to the pia mater (on the surface of teh brain and spinal chord)
59
What name do the web-like trabeculae of the arachnoid give this layer?
Gr. resembling a spider's web
| 'arachnoid' structure= 'spider-web looking' structure
60
What are the arachnoid trabeculae composed of?
- **loose** *connective tissue fibers*
- containing elongated *fibroblasts*
61
What do the arachnoid trabeculae create? What is its name? What is it filled with?
- **subarachnoid space** (spaced bridge)
- contains: **cerebrospinal fluid**
62
What is the location of the pia mater?
lies directly on the surface of the brain and spinal chord
63
What is the composition of the pia mater? What is it continuous with?
**connective tissue layer**
- continuous with the ***perivascular*** **connective tissue sheath of blood vessels** of the brain and spinal chord
64
What are the surfaces of the pia mater and the arachnoid covered with? Which parts?
- arachnoid (both surfaces)
- pia matter (inner surface)
- trabeculae
covered with **thin squamous epithelial layer**.
65
What happens to the arachnoid and pia mater as they exit the dura mater? Where does this occur?
- the arachnoid and pia mater **fuse**
- fuse around the *opening* for the cranial and *spinal nerves*
66
State the differences in thickness between the 3 meninges.
dura mater: thickest
pia mater: thinnest
arachnoid: thin however filled with cerebrospinal fluid making it look large
67
What 3 spaces exist between the membranes?
- epidural space
- subdural space
- subarachnoid space
68
Where is the epidural space located? What does it include? What is its function?
- area between the *dura mater* and the *vertebral wall*
- contains **fat** and **small blood vessels**
- **protection** from temperature changes and physical impacts (ammortisation)
| large
69
Where is the subdural space located?
- opened seperation between the *arachnoid* and *dura mater*
- doesn't really exist: arachnoid and dura mater are attached very tightly
- space can become larger due to physcial trauma
70
Where is the subarachnoid space located?
- interval between the arachnoid membrane and the pia mater
| largest space
71
What is the largest and smallest space bewteen the membranes?
largest: subarachnoid space
smallest: subdural space
72
What does the peripheral nervous system consist of?
- **peripheral nerves** with *specialized nerve endings*
- **ganglia** containing *nerve cell bodies* (residing outside the CNS)
73
What are the nerves of the PNS made up of? What are their functions?
- made up of many **nerve fibers**
- **carry** sensory and motor (effector) **information** between the organs and tissues of the body and spinal chord
74
Where can the cell bodies of peripheral nerves be located?
- within the CNS
- outside the CNS in peripheral ganglia
75
What do ganglia contain?
- *clusters* of **neuronal cell bodies**
- **nerve fibers** leading to and from cell bodies
76
What cell bodies belong to sensory neurons?
- dorsal root ganglia cell bodies
- ganglia of cranial nerves
- sensory neurons (somatic afferents and visceral afferents) = autonomic nervous system
77
What cell bodies belong to the postsynaptic (motor) neurons?
- paravertebral ganglia cell bodies
- prevertebral ganglia cell bodies
- terminal ganglia cell bodies
- motor neurons (visceral efferents)= autonomic nervous system
78
What is the ganglion? What is it made up of?
- additional *small organ*
- covered by other organs with a **irregular connective tissue capsule**
- contains **fibers** (processes of neurons)
- covered by structures such as **myelin**
79
What are the round structures in the ganglion?
bodies of pseudounipolar neurons
