Exam I | Systems Overview: Nervous System Flashcards
1
Q
Distinguish between afferent and efferent.
A
afferent is sensory function, efferent is motor function
2
Q
Somatic nervous system (4 points)
A
- voluntary
- innervates skeletal muscle
- carries sensory information originating in the skin to CNS
- acts in concert with ANS that regulates cardio-pulmonary function, response to stress, etc.
3
Q
What are glial cells?
A
- nurturing cells that support, insulate, and facilitate neurons
- differ regionally in the brain
- more abundant than neurons
4
Q
What glial cells myelinate in the CNS? PNS?
A
oligodendrocytes; Schwann cells
5
Q
How many nerve pairs are in the cervical, sacral, and coccygeal regions?
A
8, 5, and 1, respectively
6
Q
What do you call the termination of the spinal cord? Where does the spina cord end?
A
medullary cone, between L1 and L2
7
Q
Describe the relationship between the lumbar column and the lumbar region of the cord.
A
the lumbar column is inferior to the lumbar region of the cord.
8
Q
Describe the relationship between the sacrum and the sacral region of the cord.
A
the sacrum is inferior to the sacral region of the cord
9
Q
What is the cauda equina?
A
made up of lumbar, sacral, and coccygeal spinal nerve pairs
10
Q
Compare and contrast nuclei with ganglia.
A
- both are local aggregations of neurons of similar function
- but nuclei are found in CNS and ganglia are found in PNS (sensory and autonomic)
- exception is basal ganglia
11
Q
What is the difference between white and gray matter?
A
- gray matter has somas, white matter has axons
- in brain, gray matter is in cortex and white matter is in inner brain; the reverse is true in the spinal cord
12
Q
What is a tract in the CNS?
A
a pathway (aggregation of nerve fibers) interconnecting 2 or more nuclei
13
Q
What are the meninges composed of?
A
dura mater, arachnoid mater, pia mater
14
Q
What does “gracile” mean?
A
thin, slender
15
Q
What does ‘cuneate” mean?
A
wedge-shaped
16
Q
What does fasciculus mean?
A
small bundle
17
Q
What does ipsilateral mean?
A
same side
18
Q
what does contralateral mean?
A
opposite side
19
Q
What are 2 components of the dorsal lemniscus?
A
gracile fasciculus (medial) and cuneate fasciculus (lateral)
20
Q
How can syphilis affect the spinal cord over time?
A
- after 20 years of infection, it can cause progressive deterioration of the dorsal side, or tabes dorsalis.
- inflammation of dorsal roots and spinal ganglia
- necrosis of dorsal columns
21
Q
What fibers does the peripheral nervous system include?
A
- autonomic
- sensory
- motor
22
Q
what does the nuerolemma do?
A
- in myelinated axons, produces myelin that surrounds a single axon
- in a Remak bundle, a single neurolemma surrounds multiple axons (or dendrites). Does not produce myelin in this case
23
Q
what is another name for Schwann cells?
A
neurolemmocytes
24
Q
What is the epinerueum?
A
- contains fatty tissue, blood supply, and lymphatic vessels
- envelops multiple fascicles to encase entire nerve
25
What is the perineurium?
dense connective tissue that encapsulates fascicles
26
What is a fascicle?
a bundle of axons, encapsulated by the perineurium
27
what is the endoneurium?
connective tissue that wraps around myelin in the PNS
28
What is myelin composed of?
water and collagen
29
What must a local anesthetic molecule do to reach its site of action?
- site of action is the nerve axon
| - must traverse 4-5 layers of connective tissue or lipid membranous barriers, or both
30
How is the PNS divided?
- primarily into motor and sensory nerves
- motor nerves can be somatic or autonomic
- autonomic nerves can be sympathetic or parasympathetic
31
What nerves are considered part of the PNS?
- cranial nerves
| - spinal nerve pairs
32
From where do the cranial nerves originate? What is the exception?
- brainstem, exit skull via cranial foramina
| - cranial nerve XI arises from superior cord
33
How many pairs of spinal nerves are there?
31
34
What are two other names for DRG?
posterior root ganglion or spinal ganglion
35
what is another name for nerve?
root
36
Describe the pathway of a motor neuron.
- soma is in ventral horn
| - travels from there to ventral rootlets to ventral root to spinal root (nerve) to skeletal muscle
37
Describe the pathway of a sensory neuron.
- soma is in spinal ganglion (DRG)
- sensory neuron is unipolar
- travels from skin to spinal root to DRG to dorsal root to dorsal rootlets to dorsal horn
38
How does the somatic reflex response work?
- sensory neuron is connected to motor neuron by interneuron
| - AP occurs in between sensory neuron and interneuron, and between interneuron and motor neuron
39
Reflexes can fall under what two categories?
- monsynaptic (2 neurons)
- disynaptic (3 neurons)
- there's always one more neuron than there are synapses
40
What is the basal lamina, and what is another name for it?
- wraps around myelin
| - basement membrane
41
What type of nerve fibers cannot regenerate?
CNS fibers
42
In what cases can you have nerve fiber regeneration?
-in the PNS, if only the myelin sheath is damaged
43
What is Wallerian degernation?
- incomplete regeneration
- structures distal to the injury or transection undergo atrophy (including axon terminals), and for a short distance proximally
44
How does a transected nerve fiber regenerate when the myelin is relatively intact?
- growth cones and filopodia emerge from proximal axons in nerve.
- Filipodia follow contours of Schwann cell
45
What 3 things can induce nerve damage?
- bone displacement from fractures
- MVC
- ischemia
46
What determines whether or not a neuronal axon can regrow?
- the degree to which Schwann cells and neurolemma are damaged
- if they are relatively intact, there is a good chance of recovery
47
What kind of neurons does the ANS have?
- primarily classified as efferent (motor)
| - however has efferent and efferent components
48
What organs do visceral efferent fiibers innervate?
- smooth muscle
- glands
- heart
49
What 2 things do visceral afferent fibers contribute to?
- autonomic reflexes
| - homeostasis
50
If the cell body is in a ganglion, what kind of nerve is it?
peripheral and afferent (sensory)
51
The Vagus nerve provides what kind of innervation to the abdominothoracic cavity?
parasympathetic
52
If the cell body is in the ventral horn, what kind of neuron is it and what is the target tissue?
- autonomic motor neuron
| - sends autonomic signals to heart or skin (to activate erector pili muscle)
53
Distinguish between somatic sensory and visceral sensory neurons.
- somatic sensory neurons send signals mainly from integumentary sensory receptors (but also from fascia, joints, skeletal muscles, and special senses) sensitive to vibration, pain, touch, and temperature. You are aware of them (with some exceptions)
- visceral sensory neurons receive AUTONOMIC information about HR, BP, O2 levels from viscera back to the CNS. You're not aware of these sensations.
- both responsible for pain
54
Distinguish between somatic motor and visceral motor neurons.
- somatic motor are voluntary and carry info from cord to skeletal muscle
- visceral motor carry AUTONOMIC info to smooth muscle, glands, and heart
55
Describe the two divisions of the efferent autonomic nervous system.
- sympathetic (thoracolumbar): fright, fight, flight
| - parasympathetic (craniosacral): rest and digest
56
Where are the somas of the efferent preganglionic neurons of the sympathetic and parasympathetic nervous systems?
- both are found in the spinal cord
- sympathetic is found in the thoracolumbar region of the cord
- parasympathetic is in the craniosacral region of the cord (brain stem or sacral spinal cord)
57
Where are the somas of the efferent postganglionic neurons of the sympathetic and parasympathetic nervous systems?
both have soma in the autonomic ganglion and innervate smooth muscle or glands
58
What separates the pre and postganglionic neurons?
ganglion, where synapse occurs
59
How does neuron size of pre and post ganglionic neurons compare in the sympathetic and parasympathetic nervous systems?
in parasympathetic, preganglionic neurons tend to be longer and post ganglionic neurons tend to be shorter and in the target tissue
60
Dorsal and ventral roots converge to make the _____.
spinal nerve
61
What does the spinal nerve divide into?
anterior and posterior rami that carry both afferent and efferent (mixed) fibers
62
What do posterior rami innervate?
- synovial joints of vertebral column
- deep muscles of back
- overlying skin
63
What do anterior rami innervate?
- most of anterior and lateral trunk
| - both upper and lower limbs
64
What 3 things do somatic afferent fibers conduct?
- exteroception
- nociception
- proprioception
65
What sensations are exteroceptive, and where are the receptors?
- pain
- pressure
- touch
- temperature
- receptors are in skin
66
What sensations are nociceptive?
physiological pain
67
What sensations are proprioceptive, and where are the receptors?
- joint and limb position and tension
| - receptors are in muscles and tendons
68
Cervical dermatomes include what regions of the body?
- anterior and posterior shoulders
- clavicular region
- anterior and posterior neck
- posterior head
69
What regions of the body makes up the sacral dermatomes?
- posterior lower extremities
| - gluteal region
70
What region of the body makes up the lumbar dermatomes?
anterior lower extremities
71
What is the difference between a dermatome and a myotome?
- dermatome is region of skin innervated by sensory fibers from a single spinal nerve (dorsal root)
- myotome is a range of skeletal muscles (not necessarily touching) that is innervated by a single spinal nerve (more often a motor neuron)
72
Why are dermatomes important?
use in evaluating and localizing source of tactile sensation problems in patients
73
How are myotomes categorized?
by joint movement
74
Describe the structure of the para-vertebral sympathetic chain ganglia.
- start in the cervical region: there's 3 bilaterally (superior, middle, inferior)
- However, the bridges that connect them to the cord (dorsal and ventral rami) are ONLY present in the thoracolumbar region
- 3 bilateral pairs of sacral chain ganglia converge at the ganglion impar
75
Name the pre-vertebral sympathetic ganglia from most superior to most inferior.
- celiac ganglion
- superior mesenteric ganglion
- inferior mesenteric ganglion
76
Where do the pre-synaptic sympathetic neurons emerge from?
the intermediolateral column (IML) of gray matter of cord, between T1 and L4
77
Where are post-synaptic sympathetic neurons located?
in the pre-vertebral ganglia and the sympathetic chain
78
What is another name for pre-vertebral ganglia?
collateral ganglia
79
In the sympathetic nervous system, above the diaphragm, where do synapses occur?
at the paravertebral ganglia (sympathetic chain)
80
In the sympathetic nervous system, below the diaphragm, where do synapses occur?
at the pre-vertebral ganglia (collateral ganglia)
81
Where do pre-synaptic nerves merge together prior to synapsing?
at the splanchnic nerves in the prevertebral ganglia
82
Where are splanchnic nerves located?
in prevertebral ganglia
83
What is the pathway for a pre-ganglionic sympathetic axon from the cord to the sympathetic chain?
-IML-> ventral root-> spinal nerve> ventral ramus> sympathetic chain
84
Once the pre-ganglionic axon has reached the sympathetic chain, what are its options?
- may then ascend into chain to target tissue
- or synapse with post-ganglionic neuron at the same level (at chain ganglia)
- or pass through chain into splanchnic nerve and then prevertebral ganglion
85
What connects the ventral ramus to the sympathetic chain?
gray and white rami communicantes
86
what nerves does the spinal nerve contain?
- autonomic
- sensory
- motor
87
What is the anatomical position of the white ramus relative to the gray ramus communicantes?
it's more lateral
88
Describe the pathway of a post-ganglionic sympathetic neuron after it synapses at the chain ganglion
gray ramus communicantes-> anterior ramus-> peripheral nerve
89
What is meant by the phrase "sympathetic innervation is structurally divergent"?
-there are more postganglionic neurons that preganglionic neurons
90
What sympathetic receptors play a role in regulating vasomotor tone?
alpha and beta receptors
91
Functions of the sympathetic nervous system
- regulation of vasomotor tone
- pilomotion (arrector pili muscles)
- sweating (sudomotion)
92
Describe the pathway of the postganglionic neuron to the head
- cell body is in superior cervical ganglion
- leave ganglion via the cephalic arterial branch to form periarterial plexuses of nerves that may accompany carotid arteries
93
What is Horner's syndrome?
- occurs due to damage of the postganglionic neuron pathway to the head
- patients can have trouble elevating an eyelid or one pupil may be more dilated than the other
94
What nerve fibers do splanchnic nerves generally refer to?
- autonomic fibers (visceral efferents)
| - sensory fibers (visceral afferents)
95
What are the splanchnic nerves of the thoracic cavity?
- greater
- lesser
- least
96
Which splanchnic nerves are not sympathetic?
pelvic splanchnics; they are parasympathetic (craniosacral)
97
What splanchnic nerves are the largest and most likely to be encountered? What do they innervate?
- thoracic
| - primarily the GI tract and lower abdominal cavity
98
neural pathway to adrenal medulla
- preganglionic neuron does not synapse at either the sympathetic chain or at the pre-vertebral ganglia
- the adrenal medulla IS the postganglionic neuron; it is considered neural tissue (but not the cortex). It's derived from ectoderm, from which nervous tissue is also derived
99
what are the parasympathetic cranial nerves?
III (oculomotor)
VII (facial)
IX (glossopharyngeal)
X
100
What kind of ganglia are in the head? How many are there?
4 parasympathetic
101
What kind of ganglia are in the neck? How many are there?
3 sympathetic
102
For parasympathetic nervous system, everything above where the transverse colon and descending colon meet is innervated by the _______, and everything below is innervated by the ________.
vagus nerve; pelvic splanchnic nerve
103
From what two places do preganglionic parasympathetic neurons originate?
- brain stem (fibers exit with parasympathetic cranial nerves)
- sacral region of the cord (via anterior roots of spinal nerves and pelvic splanchnic nerves)
