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Anat Exam 2---2
Hamster
60
Anatomy
Undergraduate 4
10/27/2010

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Term
The three major functions of the spinal cord. And an addition function
Definition
1) Innervation: sensory and motor innervation of the body (not the head)
2) Conduction: sending signals to and from the brain (ascending and descending pathways)
3) Reflexes: mediates quick rxns to stimuli via a simple loop of afferent and efferent fibers
4) Locomotion: repetitive movements such as walking
Term
Reflexes: where does it happen and what is the benefit?
Definition
-does not involve the brain
- happens in the spinal cord
- benefit: to react before you consciously think about it
Term
Where do conscious rxns to stimuli start?
Definition
In the brain
Term
Where does the spinal cord end relative to the vertebral column?
Definition
-the spinal cord is shorter than the vertebral column
- spinal cord ends around L1/L2 as the medullary cone
Term
Why are the cervical and lumbar levels of the spinal cord so much larger than other levels?
Definition
Because the cervical and lumbar levels control more parts of the body, to innervate the limbs.
- Cervical: upper limbs
- Lumbar: lower limbs
Term
The spinal cord is associated with spinal nerves; what nervous systems are represented? (central or peripheral?)
Definition
spinal cord: CNS
spinal nerves: PNS
Term
How many spinal nerves are associated with each vertebral region? (cervical, thoracic, lumbar, sacral)
Definition
Cervical: 8; though there are 7 vertebra
Thoracic: 12
Lumbar: 5
Sacral: 5
Term
At the cervical level, the spinal nerves exit _____ the vertebra with the same number
Definition
above
Term
A spinal nerve passes through each _____ foramen
Definition
intervertebral
Term
C1=?
C2=?
Definition
C1=atlas
C2=axis
Term
Thoracic, Lumbar, and Sacral nerves exit ____ vertebra with the same number.
Definition
below
Term
The nerve root are (shorter or longer?) as you descend the vertebral column
Definition
longer
Term
Cauda equina: looks like a horse's tail
Definition
-a collection of nerve roots at the lower levels of the vertebral column (but below the spinal cord--which stops at L1/L2)
- exit the vertebral column where they need to, at the respective intervertebral foramen
Term
Spinal meninges
Definition
-protective coverings for the cord, additional layers of tissue
Term
The three layers of the spinal meninges
Definition
1) Dura mater: outer
2) Arachnoid: middle
3) Pia mater: inner
Term
Position and Contents: epidural space
Definition
fat;between the bone of the vertebra and the dura mater
Term
Position and Contents: dura mater
Definition
"tough mother"; outer layer
Term
Position and Contents: Subdural space
Definition
between the dura and the arachnoid; *not really a space though because nothing is in between them
Term
Position and Contents: Arachnoid
Definition
"spider-like"; middle, delicate, spider-webby layer
Term
Position and Contents: subarachnoid space
Definition
a substantial space; filled with CSF; between arachnoid and pia mater
Term
Position and Contents: Pia mater
Definition
="delicate mother"; fused to the surface of the spinal cord; thus the spinal cord is essential floating in CSF
Term
Small hole in the middle of spinal cord is the _____
Definition
Central canal; thus the cord is hollow like the brain, filled with CSF made by Ependymal cells
Term
What is the function of the Denticulate ligaments? (extensions of the Pia mater)
Definition
Prevent side to side movement of the spinal cord
Term
Where is the safest place to perform a spinal tap?
Definition
- the large subarachnoid space between L2 and S2
- may be done to test for meningitis
- needle passes between the spinous processes through the dura and arachnoid to enter the subarachnoid space
Term
Salient features of white matter in the spinal cord (5)
Definition
1. superficial area
2. contains only axons (fibers)
3. axons are organized into tracts, distinguished by location
4. Allows the brain and brainstem to communicate with the spinal cord
5. Allows communication between distant levels of the spinal cord
Term
Salient features of the Gray matter in the spinal cord (3)
Definition
1. Deeper area, at the center of the cord
2. contains all nerve cell bodies
3. cell bodies are separated by function and are organized in nuclei
Term
Dorsal horn receives ________ info
Definition
sensory
Term
Lateral horn
Definition
contains visceromotor cell bodies and is only present from T1-L2 and S2-S4
Term
Ventral horn
Definition
contains somatomotor cell bodies
Term
Dorsal root
Definition
collection of axons entering the spinal cord containing sensory info
Term
DRG (dorsal root ganglia)
Definition
cell bodies of dorsal root
*contains sensory info
- contain unipolar cells with central and peripheral processes
- Incoming sensory info has 2 options: ascend a tract to the brain or synapse in the spinal cord for a reflex
Term
As soon as you step off the spinal cord you're in the ____
Definition
PNS
Term
First branches of the spinal nerve:
Definition
Dorsal and Ventral rami
Term
Dorsal ramus: what does it innervate?
Definition
- both motor and sensory
- innervates muscles in the skin of the back
- heads towards the back/dorsal side
Term
Ventral ramus
Definition
- contains both motor and sensory axons
- innervates everything else, muscles and skin of anterior trunk and limbs
- larger than the dorsal ramus, b/c has more to innervate
Term
Each spinal nerve contains the same three types of fibers:
Definition
1. Sensory
2. Somatomotor
3. Visceromotor
Term
Connective tissue of Nerves
Definition
epineurium, perineurium, endoneurium
Term
epineurium
Definition
encloses the entire never--all axons
Term
perineurium
Definition
wraps around bundles/fassicles of axons
Term
endoneurium
Definition
wraps around individual axons
Term
Reflex
Definition
quick rxn, doesn't involve to brain
- the simplest kind is monosynaptic (no interneuron)
-other example: stretch reflex
Term
Besides a reflex, what else can make a motor neuron (and ultimately a muscle) fire?
Definition
Descending input from higher brain centers via axons bundled into tracts; voluntary
Term
Motor neurons
Definition
* cannot fire w/o input
- Two sources of input:
1. Incoming sensory input for a Reflex--involuntary
2. Descending input from higher brain centers; Conscious choice--voluntary
Term
Spinal cord tracts
Definition
Bundles of axons that allow communication between the spinal cord and the brain.
Term
4 major ascending and descending paths
Definition
1. Dorsal columns
2. Dorsal Spinocerebellar tract (DSCT)
3. Lateral Spinothalamic tract aka Anterolateral
4. Lateral Corticospinal tract (LCST): major voluntary contraction pathway
Term
Dorsal columns; sensory modalities?
Definition
- fine touch, vibration, conscious proprioception
Term
General sensory neurons: unipolar, bipolar, or multipolar?
Definition
unipolar
Term
Two subdivisions of the Dorsal Columns
Definition
1. Fasciculus Gracilis
2. Fasciculus Cuneatus
Term
The first order neuron for ascending pathways is always in the ___
Definition
DRG
Term
1st, 2nd, and 3rd order neuron locations for the dorsal columns
Definition
1st: DRG
2nd: brainstem (medulla)
3rd: thalamus, then up to the cerebral cortex and then you are consciously aware of it
Term
In the dorsal column, axons from different parts of the body are found in specific sites
Definition
FG: T7-S5
FC: C2-T6
Term
2nd order neurons of the dorsal columns: location and names
Definition
medulla; nucleus cuneatus and nucleus gracilis
Term
Dorsal columns (Summary): 1. Type of info involved 2. Locations of 1st, 2nd, and 3rd order neurons 3. Ipsilateral or contralateral?
Definition
1. fine touch, vibration, conscious propioception
2. 1st: DRG; 2nd: medulla 3rd: thalamus
3. contralateral: the 2nd order neuron switches to the opposite side
Term
Deficits after a dorsal column legion: ipsi or contralateral?
Definition
Ipsilateral loss of fine touch, vibration, and conscious propioception
Term
ALS/spinothalamic tract: Summary 1. Info involved? 2. Locations of 1st, 2nd, and 3rd neurons 3. Ipsilateral or Contralateral?
Definition
1. pain, temperature
2. 1st: DRG; 2nd: dorsal horn; 3rd: thalamus
3. Contralateral
Term
Similarities between dorsal columns and ALS
Definition
- 1st order in the DRG
- three neurons in pathway
- 3rd order neuron in the thalamus
- cross to contralateral side
- terminate in the cerebral cortex
Term
Dorsal Spinocerebellar Tract (DSCT): What type of Info does it carry?
Definition
-unconscious propioception, "muscle sense"
- info from sensory receptors in the sk muscles (GTO's and Muscle spindles)
- involved in reflexes
- supplies the cerebellum with info about the muscle: unconscious proprioception
Term
DSCT: 1st ans 2nd order neurons
Definition
1st: DRG
2nd: Clark's column in the dorsal horn; this second axon ascends in the DSCT and terminates in the cerebellum
Term
DSCT: how is it different from dorsal columns and ALS?
Definition
- only two neurons
- ends in the cerebellum (unconscious)
- entirely ipsilateral
Term
Deficits of the DSCT
Definition
- always ipsilateral
- incoordination
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