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