Week 1 - C - Neuroanatomy 2 - Spinal Anatomy And Tracts

Question 1

In the spinal cord there are how many paired nerves? What do the cervical and lumbar enlargement portions of the spinal cord supply?

Answer 1

31 paired spinal nerves Cervical supplies upper limb Lumbar supplies lower limb

Question 2

How is the anterior rami formed from the spinal cord?

Answer 2

The spinal cord gives off anterior rootlets that come together to make anterior roots The anterior and posterior roots then fuse together to form the spinal nerve at the intervertebral foramen which splits into the anterior and posterior rami

Question 3

What is contained into the dorsal root ganglion of the posterior root?

Answer 3

This contains cell bodies of sensory neurons

Question 4

The spinal cord terminates in a tapered cone-shape called the what? What vertebral level is this usually?

Answer 4

This is the conus medullaris L2

Question 5

What is the continuation of the spinal cord composed of pia mater that runs from the conus medullaris to the coccyx? What is the function of this cotninuation?

Answer 5

This is the filum terminale - this anchors the spinal cord

Question 6

The spinal meninges are continuous with the cranial meninges via the foramen magnum. What are the three meningeal layers?

Answer 6

This would be the dura mater, arachnoid mater and pia mater

Question 7

Just as the filum terminale anchors the spinal cord, what is the ligament that attaches the lateral aspect of the spinal cord to the dura matter known as and helps anchor the spinal cord?

Answer 7

This is the denticulate ligament and is composed of pial and arachnoid tissue

Question 8

Is white or grey matter on the outside of the spinal cord? Which is H shaped?

Answer 8

The white matter is on the outside of the spinal cord with the grey matter in the H shaped inside

Question 9

A small central canal extends the length of the spinal cord. What does this open into rostrally?

Answer 9

This opens into the 4th ventricle

Question 10

The white matter is conventionally described as being made up of posterior, lateral (x2), and anterior funiculus, what is the smaller divisions of the funiculus known as? What is the grey matter of the spinal cord divided into?

Answer 10

Smaller divisions of funiculus are known as fasiculus It is divided into 4 horns left and right anterior and posterior horns hence the H shape

Question 11

How is it possible to tell apart the anterior and posterior horns if given an unlabelled spinal cord?

Answer 11

The posterior horns extend fully through the white matter of the spinal cord

Question 12

At spinal segments T1 to L2 there is also a smaller lateral horn What is contained in the lateral horns here?

Answer 12

The preganglionic sympathetic neurons for thoracolumbar outflow lie here

Question 13

The arterial blood supply to the spine contains 5 main arterial supplies What are they? and where are they derived from?

Answer 13

3 longitudinal arteries One anterior and 2 posterior that originate from the vertebral arteries Segemntal arteries derived from the vertebral, intercostal and lumbar arteries Radicular arteries derived from ventral and dorsal nerve roots

Question 14

What are the venous drainage veins of the spinal cord known as?

Answer 14

These are the longitudinal and sentimental veins

Question 15

What is the space between the dura mater and bone of the vertebra that can be used for anaesthesia? Why must you be careful when accessing this space?

Answer 15

This is the epidural space This is because in this space venous plexus’ exist and dont want to rupture one causing an epidural haemorrhage

Question 16

Where is the primary somatosensory cortex? Which love is it in?

Answer 16

It is located posterior to the central sulcus in the post-central gyrus It is in the postcentral gyrus of the parietal lobe

Question 17

Where is the primary motor cortex?

Answer 17

This is in he precentral gyrus located in the frontal lobe

Question 18

What is the major ascending spinal tract involved in fine touch and conscious proprioception? What is proprioception?

Answer 18

This would be the dorsal column/medial lemniscus spinal tract Proprioception is understanding ones movement in space

Question 19

Where do the fibres cross over in the dorsal column? What is crossing over also known as?

Answer 19

They cross over in the medulla It is known as decussation

Question 20

What is the word column in dorsal column also known as?

Answer 20

This is also known as the dorsal funiculus

Question 21

What does the dorsal funiculus contain?

Answer 21

Contains the fasciculus gracilis and fasciculus cuneatus

Question 22

Where do the axons for the fasciculus gracilis and the fasciculus cuneatus come from?

Answer 22

Fasciculus gracilis (graceful leg) - comes from the lower limb Fasciculus cuneatus - comes from the upper limb

Question 23

Does the fasciculus cuneatus or gracilis lie medial to one another?

Answer 23

The fasciculus gracilis lies medial to the fasciculus cuneatus

Question 24

In the dorsal column, explain the pathway if the axons came from eg the upper limb? (remember the 1st order, 2nd order and 3rd order neruones)

Answer 24

https://s3.amazonaws.com/classconnection/403/flashcards/11907403/png/picture1jpggifjpggif-15E344988D821EF1706.png

Question 25

Where do the synapses occur in the dorsal colum tract? Where does crossing over occur? What functions does the system help with?

Answer 25

Synapses occur in the cuneate/gracilis nucleus of the medulla Also in the thalamus Crossing over occcurs in the medulla where the second order neurones then follow the medial lemnsicus pathway Helps with fine touch, vibration&proprioception

Question 26

Now talked over the dorsal column/medial lemniscus pathway What is the other major sensory pathway?

Answer 26

This is the spinothalamic tract

Question 27

What sensations does the spinothalamic tract carry?

Answer 27

This tract carries deep pressure, pain (nociceptive) and temperature

Question 28

The dorsal column tract is clearly located in the dorsal column (funiculus) of the spinal cord Where does the spinothalamic tract lie?

Answer 28

The spinothalamic tract lies in the anterolateral region of the spinal cord

Question 29

What is another name for the spinothalamic tract?

Answer 29

The anteriolateral system

Question 30

Where do the first order neurones enter the spinothalamic tract?

Answer 30

They are carried along axons past the dorsal root ganglion and into a tract in the dorsal column called lissauer’s fasiculus

Question 31

What happens after the neurones reach lissauer’s fasciculus ? (say up to how they begin the spinothalamic tract from the anterolateral wall of the spinal cord)

Answer 31

The fibres travel in lissaeuers fasciculus from the white matter to the dorsal horn of the grey matter where they synapse in the substantial gelatinosa (usually a couple of vertebral levels above entry) and the second order neurones decussate to the anterolateral region of the spinal cord and travel up the spnothalamic tract in the axons

Question 32

Once the 2nd order neurones are in the spinothalamic vesiculus, hw do they end up in the postcentral gyrus?

Answer 32

They synapse again in the thalamus and the third order neurones travel to the primary somatosensory cortex in the postcentral gyrus of the parietal lobe

Question 33

Talk through from body touch to the postcentral gyrus for the spinothalamic tract?

Answer 33

https://s3.amazonaws.com/classconnection/403/flashcards/11907403/png/picture1jpggifjpggif-15E3473A5830E8DE02C.png

Question 34

The spinothalamic tract has the anterior and lateral spinothalamic tracts although they run alongside each other so are considered as one Which of the sensations do the anterior and lateral tracts carry? Where does decussation occur in the spinothalamci tract?

Answer 34

• The anterior tractcarries pressure - The lateral tract carries temperature and pain - Synapses occur in - the substantia gelatinosa of the dorsal horn of they grey matter in the spinal cord, & in the thalamus -Decussation occurs in the spinal cord also instead of the medulla like the dorsal column tract

Question 35

What is the difference between upper and lower motor neurons?

Answer 35

Upper motor neurones originate in the motor region of the brain and travel down The lower motor neuron recieves information from the upper motor neurone (basically after the upper synaspes) and connects to the muscle/limb it supplies

Question 36

What is the main descending spinal cord tract?

Answer 36

This would be the corticospinal tract

Question 37

What is the motor function of the corticospinal tract?

Answer 37

It carries fine, precision movmeent and motor to limb muscles and axial muscles

Question 38

When the precentral gyrus (primary motor cortex) gives the signal for a movmeemnt, the neuron begins its travel Where does the neurone decussate for the lateral corticospinal tract?

Answer 38

The neuron travels past the thalmus and through the midbrain/pons to the medulla where the neurones decussaye to travel to the spinal cord

Question 39

What percentage of the neurones decussate in the medulla for the corticospinal tract? What out of the corticospinal tract motor functions will the lateral tract control?

Answer 39

85% decussate at the medulla and the lateral tract will give lower motor neurons to the limb muscles

Question 40

When the axial axons get to there desired levels by travelling down the naterior cortciospinal tract, where do they decussate?

Answer 40

They decussate to the anterior grey matter horn in the spinal cord at the appropriate level and supply the axial muscles

Question 41

Where do both the lateral and anterior corticospinal tracts synapse before giving lower motor nueornes to the muscles?

Answer 41

In the anterior horn of grey matter

Question 42

Why is the corticospinal tract sometimes reffered to as the pyramidal tract? What percentage of axons decussate at the medulla to become part of the lateral corticsopinal tract? Which muscles do the lateral and anterior tracts supply respectively? Where does the synapse occur?

Answer 42

This is because the tract forms visible ridges referred to as the ‘pyramids’ on the anterior surface of the medulla, so also called the pyramidal tract. 85% decussate at the medulla pyramids The lateral corticospinal tract supplies the limb muscles The anterior corticsopinal tract supplies the axial muscles The synapse occurs in the corticopsinal tract in the anterior horn of the grey matter in the spinal cord

Question 43

Which tract provides sensation for fine touch, vibration and proprioception? WHich tract provides motor control to the limbs and axial muscles? What tract provides sensation for deep pressure, temperature and pain?

Answer 43

This would be the dorsal column / medial lemnsicus tract The corticospinal tract - lateral corticospinal for limb muscles and anterior cortiocspinal for axial muscles Deep pressure, temp and pain would be the spinothalamic tract

Question 44

Would a lesion in the spinal cord cause contralteral or isilateral damage to the spinothalamic tract? WHat symptoms would be seen? Would a lesion in the spinal cord cause contralteral or isilateral damage to the DCML tract? What symptoms would be seen? Would a lesion in the spinal cord cause contralteral or isilateral damage to the corticospinal tract? If this is a hemisection of the spinal cord, what syndrome are these symptoms known as?

Answer 44

https://s3.amazonaws.com/classconnection/403/flashcards/11907403/png/picture1jpggifjpggif-15E388A626221A664D9.png

Question 45

What would happen if there was damage to the left corticospinal tract?

Answer 45

There would be hemiplegia of the right upper and lower limbs

Question 46

If there was a stroke or CVA occuring in the precentral gyrus, what tract would be affected?

Answer 46

This would affect the primary motor cortex casuing the affected tract to be the corticospinal tract

Question 47

Where are the primary motor and primary somatosensory cortex located? (lobe included)

Answer 47

Primary motor cortex - located in the precentral gyrus of the frontal lobe (just like anterior rootlets have motor axons in the spine) Primary somatosensory cortex - located in the postcentral gyrus of the parietal lobe (just like posterior rootlets have sensory axons in the spine) The precentral and postcentral gyrus - separated by central sulcus

Question 48

Regarding the homunculus, how would a lesion located in the logntiduinal fissure side of the primary somatosensory cortex differ from a lesion near the longitudinal fissure side of the primary motor cortex? (ie arms or legs)

Answer 48

It wouldnt differ, the legs would be affected If the lesions was further along the pre/post central gyrus then the arms would be affected

Question 49

There are a number of motor systems outside of the pyramidal tract and these are often referred to collectively as the “extrapyramidal system”. Which tract is thought to mediate reflex head and neck movement due to visual stimuli.? Where segemnt of the spinal cord does the axons input to mainly?

Answer 49

The tectopsinal tract is though to facilitate head and neck movements Its main input is to the cervical cord

Question 50

Where does the tectospinal tract begin and end?

Answer 50

The tectospinal tract begins in the tectum of the midbrain and ends in the anterior horns of mainly the cervical cords

Question 51

Reticular formation forms the central core of the brainstem. It has many nuclei and receives input from virtually all parts of the CNS. It has many functions, including the influencing of voluntary movement. Fibres originate in areas of the reticular formation in pons and medulla. In general is it fibres that originate in the pons that facilitate extensor movmements and inhibit flexor or the opposite?

Answer 51

In general it is fibres that originate in the reticular formation of the pons that facilitate extensor movements and inhibit flexor movements Fibres originating in the medulla inhibit extensor movements and facilitate flexor movements

Question 52

What is the descending motor tract that is ipsilateral?

Answer 52

This is the vestibulospinal tract - important for balance of the head when moving (vestibular - balance nerve)