Term
| What are the two sections of the PNS? |
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Definition
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Term
| What is the function of the somatic nervous system? the autonomic? |
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Definition
| To provide voluntary motor control and general sensation information; to provide involuntary motor control and visceral sensory perception |
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Term
| How many spinal nerves are there? |
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Definition
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Term
| Where to spinal nerves exit the VC? |
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Definition
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Term
| What occurs after they have left the intervertebral foramen? |
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Definition
| The spinal nerve splits into a small dorsal ramus and a large ventral ramus |
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Term
| (T/F) All spinal nerves split after they have left the vertebral column |
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Definition
| False, the sacral nerves don't |
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Term
| What is different about the sacral nerves? |
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Definition
| They split into dorsal and ventral rami before leaving the foramina |
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Term
| Where are the cell bodies of the motor nerves located? Which pathway do their axons travel down? |
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Definition
| Anterior horn; travel in the anterior root |
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Term
| Where are the cell bodies of the sensory nerves located? |
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Definition
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Term
| (T/F) Sensory neurons have only one axon |
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Definition
| False, they have peripheral and central |
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Term
| What is the function of the peripheral sensory axon? |
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Definition
| To communicate with the DRG from the periphery |
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Term
| What is the function of the central sensory axon? |
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Definition
| To synapse with another cell body in the dorsal horn of the cord |
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Term
| How many spinal nerves are there in each section? How to they exit the VC? |
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Definition
1. 8 Cervical nerves - above respective vert
2. 12 Thoracic - below respective vert
3. 5 Lumbar - below respective vert
4. 5 sacral - below respective vert
5. 1 or 2 coccygeal nerves |
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Term
| Name the two general types of pathways in the SNS? Are the ascending or descending? |
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Definition
1. Sensory pathways (asc)
2. Motor pathways (desc) |
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Term
| How many neurons does the sensory pathway consist of? |
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Definition
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Term
| How many neurons does the motor pathway consist of? |
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Definition
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Term
| Describe the pathway of a sensation experienced on the body surface and on the deep structures to the cortex? |
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Definition
| Carried to the brain via the spinal cord, brain stem, thalamus and internal capsule |
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Term
| Name the 6 sensory modalities |
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Definition
1. Discriminatory touch
2. Pain
3. Temperature
4. Joint position (proprioception)
5. Vibration
6. Non-discriminatory touch |
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Term
| (T/F) The different tracts do not specialize which type of signal they carry |
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Definition
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Term
| Name the two sensory columns of the spinal cord? |
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Definition
1. Dorsal column (fasciculi) (2x)
2. Aterolateral column (fasciculi) (2x) |
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Term
| What sensations do the dorsal fasciculi carry? |
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Definition
- Discriminatory touch
- Proprioception
- Vibration |
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Term
| What two columns are found within the dorsal column, and which is more medial? |
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Definition
1. Fasciculus gracilis (more medial)
2. Fasciculus cuneatus (more lateral) |
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Term
| What fibres does the FG carry? |
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Definition
| Fibres originating from below T6 |
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Term
| What fibres does the FC carry? |
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Definition
| Fibres originating from above T6 |
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Term
| What structure does FG fibres synapse with secondary fibres in? FC fibres? Where are these structures located? |
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Definition
FG - nucleus gracilis
FC - nucleus cuneatus
- both of these nuclei are located in the lower medulla |
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Term
| What occurs after this synapse? |
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Definition
| The secondary axons cross over (aka the signal becomes contralateral) and then they keep ascending |
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Term
| What is the medial lemniscus? |
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Definition
| The structure that the secondary axons travel through the brainstem in. |
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Term
| What structure do these secondary axons synapse at? |
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Definition
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Term
| Describe what occurs after this synapse? |
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Definition
| Signals travel through the internal capsule then to the post central gyrus (in the sensory cortex) contralateral to the side of perception |
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Term
| * Dorsal columns do not cross over until medulla* |
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Definition
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Term
| What sensations do the anterolateral columns carry? Which ones are in the lateral column? The anterior column? |
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Definition
| Crude touch (anterior), pain and temperature (lateral) |
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Term
| How many anterolateral columns are there? |
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Definition
| 2 (one for each side of the body) |
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Term
| What is the difference between anterolateral sensatory nerves, and dorsal sensatory nerves? |
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Definition
Dorsal: enter dorsal rool/horn but DO NOT synapse until the medulla - stay ipsilateral
Anterolateral: synapses in dorsal horn @ level of the nerve entrance |
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Term
| What occurs after the anterolateral nerves synapse? |
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Definition
| The secondary neurons cross the spinal cord right away (aka signal becomes contralateral as soon as it enters the spinal cord) and ascends the spinal cord |
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Term
| (T/F) They usually cross over within three segments |
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Definition
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Term
| What do the anterolateral sensory nerves ascend in? |
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Definition
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Term
| Describe the pathway of a signal after the secodnary nerve has crossed over? |
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Definition
| Nerve ascends and joins the medial lemniscus; synapses for a second time in the thalamus, then travels through the internal capsule to the post central gyrus of the sensory cortex |
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Term
| What is the function of the motor pathways? |
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Definition
| To initiate movement in the muscles |
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Term
| (T/F) The corticospinal (aka pyramidal) tract is the only tract |
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Definition
| False, there is the extrapyramidal system as well |
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Term
| (T/F) The corticospinal (aka pyramidal) tract is the most direct motor pathway |
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Definition
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Term
| Describe the pathway of corticospinal motor fibres from their origin until the level of the medulla? |
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Definition
| Motor activity is initiated in both the motor and pre-motor cortex (which is anterior to the motor cortex). The fibres travel through the internal capsule, cerebral peduncles, the pons and then through the pyramids of the medulla. |
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Term
| What two corticospinal pathways are created at the lower medulla? |
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Definition
1. Lateral corticospinal
2. Anterior corticospinal |
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Term
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Definition
| Most of the motor fibres crossover (decussate) but some remain on the same side |
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Term
| Which tract contains fibres that have crossed over? Which contains the ipsilateral fibres? |
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Definition
Lateral corticospinal - decussated fibres (contralateral)
Anterior corticospinal - ipsilateral fibres |
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Term
| (T/F) Most fibres remain ipsilateral after they go through the medulla |
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Definition
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Term
| Where do the fibres of the anterior tract cross over? |
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Definition
| Close to where they terminate |
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Term
| Where do the both fibres in the anterior tract, and in the lateral tract, synapse? |
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Definition
| They synapse in the anterior horn of the spinal cord |
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Term
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Definition
| Now all the signals are contralateral, and the large anterior horn neurons have axons that exit the SC via the ventral roon and subsequently form the spinal nerve |
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Term
| Name the 3 tracts that make up the extrapyramidal system |
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Definition
1. Rybrospinal
2. Vestibulospinal
3. Reticulospinal |
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Term
| Where do these pathways originate? What are they involved in? |
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Definition
- Lower parts of the brain and brainstem
- Invlved in muscle tone and control, as well as some extensor control |
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Term
| (T/F) It is possible to train the extra pyramidal patwhays to take over (in a limited way) from a compromised pyramidal system |
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Definition
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