Spinal cord

Question 1

How many cervical nerves are there?

Answer 1

8

Question 2

How many cervical vertebrae are there?

Answer 2

7

Question 3

How many thoracic nerves are there?

Answer 3

12

Question 4

How many lumbar nerves are there?

Answer 4

5

Question 5

How many sacral nerves are there?

Answer 5

5

Question 6

How many coccygeal nerves are there?

Answer 6

1

Question 7

Where are the cervical nerves?

Answer 7

Above the cervical vertebrae

Question 8

Where are all other non-cervical nerves?

Answer 8

Below their respective vertebra

Question 9

What is the cauda equina?

Answer 9

Bundle of nerves that continue after the end of the spinal cord (conus medullaris)

Question 10

What is the conus medullaris?

Answer 10

The cone-shaped portion that marks the end of the spinal cord (L1/L2 vertebrae)

Question 11

Where do the ventral roots leave the spinal cord?

Answer 11

At the anterolateral sulcus

Question 12

Where do the dorsal roots leave the spinal cord?

Answer 12

At the posterolateral sulcus

Question 13

What do the ventral and dorsal roots form?

Answer 13

Spinal nerve

Question 14

What are denticulate ligaments? Where are they found?

Answer 14

Pia mater attaching to arachnoid mater - found in the spaces between spinal nerves

Question 15

Where is the anterior spinal artery found?

Answer 15

In the anterior median fissure

Question 16

Why do thoracic nerve roots extend downwards and not straight out?

Answer 16

Because they have a longer trajectory due to the lumbosacral development

Question 17

What is the filum terminale?

Answer 17

Pia mater that attaches to the coccygeal bone

Question 18

Where does the dural sac end?

Answer 18

At S2

Question 19

Where is a spinal tap/epidural usually done?

Answer 19

At L4/L5 vertebrae, because we are past the spinal cord but still in the dural sac (epidural space for epidural, dural sac for spinal tap)

Question 20

Where are there enlargements of the horns?

Answer 20

At the cervical and lumbar vertebrae

Question 21

What are radicular arteries?

Answer 21

Arteries that go through the ventral and dorsal roots and anastomose with the spinal arteries (posterior radicular - posterior spinal, anterior radicular - anterior spinal)

Question 22

Where do the posterior spinal arteries lie?

Answer 22

Posterior median sulcus

Question 23

Where does the anterior spinal artery lie?

Answer 23

Anterior median fissure

Question 24

What part of the spinal cord do the posterior spinal arteries supply?

Answer 24

Small part of the white matter (between posterior horns)

Question 25

What part of the spinal cord does the anterior spinal artery supply?

Answer 25

All of the grey matter and the majority of the white matter

Question 26

What do pial branches supply?

Answer 26

Outer edges of the white matter of the spinal cord (sacral sparing)

Question 27

What is the dorsal primary ramus? Where does it go?

Answer 27

The first branch that went to the back - goes to erector spinae muscles (dorsal trunk)

Question 28

What is the ventral primary ramus? Where does it go?

Answer 28

The first branch that went to the front - goes to everything except the erector spinae muscles (ventral trunk and all limbs)

Question 29

What are the dorsal and ventral rami?

Answer 29

Pathways for motor/sensory neurons

Question 30

What are cutaneous branches?

Answer 30

Pathways for a sensory neuron

Question 31

What are the cutaneous branches?

Answer 31

Posterior cutaneous branches Lateral cutaneous branches Anterior cutaneous branches

Question 32

What does the ventral rami supply?

Answer 32

Anterior trunk and limbs

Question 33

What does the dorsal rami supply?

Answer 33

Posterior body trunk

Question 34

What are segmental spinal nerves?

Answer 34

Spinal nerves that arise from a certain spinal level (ex: T1) and innervate somatic structures derived from somites of the same level (T1)

Question 35

What nerves in the dorsal rami are segmental?

Answer 35

All of them (C1 - coccyx)

Question 36

What nerves in the ventral rami are segmental?

Answer 36

Only intercostal nerves (t2-T12)

Question 37

What are non-segmental nerves?

Answer 37

Nerves that fuse to form a nerve plexus (network of interjoining nerves)

Question 38

What are the 4 plexuses and what nerves do they correspond to?

Answer 38

Cervical plexus (C1-C4) Brachial plexus (C5-T1) Lumbar plexus (L1-L4) Sacral plexus (L4-S2)

Question 39

What is a dermatome?

Answer 39

An area of skin that gets its sensation from a specific spinal nerve root (each sensory nerve supplies one)

Question 40

What are the sensory long axon tracts?

Answer 40

Dorsal columns-medial lemniscus tract Spinothalamic tract Dorsal spinocerebellar tract Cuneocerebellar tract

Question 41

What is the motor long axon tract?

Answer 41

Corticospinal tract

Question 42

What does the dorsal columns-medial lemniscal pathway carry?

Answer 42

Discriminative touch (can tell what I'm touching with eyes closed) and conscious proprioception (thinking of where ones body is in space)

Question 43

Where is the first synapse in the dorsal columns-medial lemniscal tract? What nucleus is it?

Answer 43

At the medulla - gracile and cuneate nuclei

Question 44

Where is the second synapse in the dorsal columns-medial lemniscal tract? What nucleus is it?

Answer 44

At the thalamus - ventral posteriorlateral (VPL) nucleus

Question 45

What is the gracile tract for?

Answer 45

Lower limbs

Question 46

What is the cuneate tract for?

Answer 46

Upper limbs

Question 47

Where do sensory neurons enter the spinal cord at?

Answer 47

Lissauer's tract (dorsal root entry zone)

Question 48

What is the medial lemniscus?

Answer 48

The part of the tract between the medulla and thalamus that "ribbons"/does not go in a straight line

Question 49

Where is the first synapse for the spinothalamic tract?

Answer 49

Immediately as the neuron enters the spinal cord (at the substantial gelatinosa)

Question 50

Where is the decussation in the spinothalamic tract?

Answer 50

Right after the first synapse (substantia gelatinosa)

Question 51

Where is the second synapse in the spinothalamic tract? What nucleus is it?

Answer 51

At the thalamus - ventral posteriorlateral nucleus

Question 52

What is the spinothalamic tract pathway for?

Answer 52

Somatic pain sensations

Question 53

What is the spinothalamic tract pathway for upper and lower limbs?

Answer 53

The same

Question 54

Which hemisphere feels pain to the left leg? What is this phenomenon called?

Answer 54

The right hemisphere = contralateral analgesia

Question 55

What are the 2 neuron tracts in the corticospinal tract?

Answer 55

Upper motor neuron tract & lower motor neuron tract

Question 56

When does the upper motor neuron tract become the lower motor neuron tract?

Answer 56

At the first synapse (ventral horn)

Question 57

Where does the corticospinal tract decussate?

Answer 57

Between the medulla and spinal cord

Question 58

What is contralateral vs ipsilateral?

Answer 58

Contralateral = left side of the brain feels sensation/controls the right side (opposite side) Ipsilateral = left side of the brain feels sensation/controls the left side (same side)

Question 59

Which tracts are contralateral? Ipsilateral?

Answer 59

Contralateral = Dorsal columns-medial lemniscus, spinothalamic, corticospinal Ipsilateral = dorsal spinocerebellar, cuneocerebellar

Question 60

Where do the cerebellar tracts entre the cerebellum?

Answer 60

In the inferior cerebellar peduncle

Question 61

Neurons for what part of the body go through the dorsal spinocerebellar tract?

Answer 61

Lower limbs

Question 62

Neurons for what part of the body go through the cuneocerebellar tract?

Answer 62

Upper limbs

Question 63

Where is the synapse for the dorsal spinocerebellar tract? Which vertebrae does it correspond to?

Answer 63

The dorsal nucleus of Clarke - C8-L2

Question 64

In order, which long tract sensory neurons are fastest to slowest?

Answer 64

Spinocerebellar - dorsal columns - spinothalamic

Question 65

Where do axons below L2 synapse in the dorsal spinocerebellar tract?

Answer 65

Still at Clarke's nucleus, they just hitchhike up to L2

Question 66

Where does the cuneocerebellar tract synapse?

Answer 66

At the accessory cuneate nucleus

Question 67

What are peduncles? How many are there?

Answer 67

Axon bridges that connect the cerebellum to the brainstem. There are 3

Question 68

What are the 3 vascular systems in the spinal cord?

Answer 68

Posterior spinal arteries, anterior spinal artery, pial branches of the radicular arteries

Question 69

What is sacral sparing?

Answer 69

The preservation of sensory or motor function in the sacral region of the spinal cord following an injury, due to pial branches Ex: if there is an injury to the anterior spinal artery, there would still be function to the spinocerebellar tracts because they are vascularized by pial branches