Neurology Anatomy -Spinal Cord And Spinal Nerves

Front 1

How are the cunate and gracile tracts similar?

Back 1

they carry information to the cortex about:
1. discriminatory touch
2. proprioception
3. vibration

Front 2

How are the cuneate and gracile tract different?

Back 2

cuneate tract carries information from the upper part of SC (above T12)

gracile carries information from below T12

Front 3

True or false:

Cuneate and Gracile tracts decussate after they join together at the brain stem?

Back 3

False

Cuneate and Gracile tracts join in the spinal cord

They do, however, decussate after the brainstem

Front 4

Name the 3 main tracts of the lateral white column

Back 4

1. Spinothalamic Tract (StT)
2. Spinocerebellar Tract (ScT) -focus on dorsal
3. Corticospinal Tract (CsT) -focus on lateral

Front 5

What information does the StT carry?

Describe where the tract goes

Back 5

Mainly pain and temperature
(also carries SIMPLE touch and pressure)

Starts from the dorsal root ganglia -> dorsal horn -> nucleus proprius -> decussate (in SC) ->axons form StT around ventral horn -> ascends and more axons are added on as it proceeds upwards -> brainstem (BS) -> thalamus -> cortex

Front 6

What information does the ScT carry

Describe where the tract goes

Back 6

Carries: unconscious proprioception for coordination of movement

Splits into dorsal and ventral
Neurons originate from the nucleus dorsalis (in the intermediate zone)
Ends in the cerebellum (without decussating)

Does NOT go to the CORTEX

Front 7

What information does the CsT carry

Describe where the lateral tract goes

Back 7

Unlike the other two, CsT is a descending tract and it controls voluntary movement

cerebral cortex (esp. precentral motor cortex) -> brainstem -> decussate -> SC -> at all levels, the axons terminate on motor neurons in the adjacent ventral horn

Front 8

If there is a lesion that affects ScT and DCT, what would you expect?

Back 8

You'd lose proprioception on the ipsilateral side (ScT and DCT) and tactile loss (DCT)

DCT = conscious proprioception
SCT= unconscious proprioception

Front 9

Describe the patter of degeneration of motor and sensory neurones after a SC transection.

Back 9

Sensory neurons degenerate above the transection

Motor neurons degenerate below the transection

Front 10

Why is at transection of C1, C2 or C3 fatal?

Back 10

You lose innervation of the diaphragm (phrenic nerve) and respiratory muscles

Front 11

Explain what happens with a C4, C5 transection.

Back 11

quadriplegia, lost of all sensation below level of lesion and loss of voluntary control of bowel and bladder

Front 12

True or False

Lesions in the thoracic region causes paraplegia but no loss of voluntary control over bowel and bladder

Back 12

False

There is loss of control over bowel and bladder

Front 13

What is an upper motor neurone paralysis?

Describe 3 ways it can occur

Back 13

UMNP : paralysis resulting from damage to the CsT (extensive voluntary paralysis)

1. stroke in the cerebral cortex
2. loss of blood supply to the tract
3. transection

Front 14

What are the typical features of UMNP?

And give an explanation for why they occur

Back 14

1. widespread voluntary paralysis
2. increase muscle tone in paralysed muscles
3. exaggerated tendon reflexes in paralysed muscles

Surviving nerve supply allows reflex activity and maintenance of muscle tone

Front 15

True of false

a peripheral nerve lesion is a typical lower motor neuron lesion?

Back 15

True

Front 16

What does lower motor neurone paralysis refer to?

Back 16

LMNP: loss of ventral horn cells or ventral roots or spinal nerves

Front 17

What are the typical features of LMNP?

And give an explanation for why they occur

Back 17

1. restricted area of voluntary paralysis

And affected muscles display:
2. no muscle tone
3. atropy
4. no tendon reflexes

Front 18

What is spinal shock?

Back 18

a period of 2-6 weeks of no spinal reflexes and flaccid muscle tone (despite type of lesion) following severe brain or SC injuries to CsT (UMNP)

Front 19

What is the most frequent UMN lesion?

Back 19

capsular stroke

vascular accident in the internal capsule

Front 20

Do skilled movements return after a SC lesion involving CsT?

Back 20

Very poor recovery for skilled movements (distal muscles)

Proximal muscles recover better

RULE: lesion in the forebrain =better movement recovery than lesion in the SC

Front 21

True of False:

CsT is the ONLY tract that deals with skilled movements, particularly of the hands

Back 21

True

Front 22

What are the three types of spinal reflexes?

Back 22

1. Flexor reflex
2. Stretch reflex
3. gamma reflex loop

Front 23

Describe how the Flexor Reflex works

Back 23

1. Painful/Tactile stimulus

2. spinal interneurone (dorsal horn)

3. alpha cells (ventral horn)

4. motor end plate in somatic muscle

5. movement

Front 24

Describe how the Stretch Reflex works

Note: Stretch reflex is for adjustment in muscle tone

Back 24

Ia sensory neurons supplies neuromuscular in tendionous insertion of muscle (parallel to axons of somatic muscles)

1. Slight stretch of muscle, stretches neuromuscular spindles

2. Ia stimulated

3. alpha motor cells get the signal (ventral horn)

4. Signals motor end plate in somatic muscles

5. Adjustment in muscle tone

Front 25

Describe how the gamma reflex loop works

Note: this reflex is for

A. maintenance of posture, equilibrium and basic movements

B. maintain the sensitivity of neuromuscular spindles

Back 25

Function A

1. Axons from BS (reticular formation) -> SC

2. synapse with gamma motor cells

3. gamma motor cells (ventral horn) innervate Ia sensory neurons ("trick" Ia neurons into activating without muscle stretch in the periphery)

4. alpha cells activated

5. Increase tone in muscles

Function B
When a muscle contracts, the tension is relieved on the neuromuscular spindles thus Ia neurones will be insensitive to stretch. Gamma cells regular this when they fire, as they will cause the neuromuscular spindles to contract, restoring tension and sensitivity at any given muscle length

Front 26

What level of the vertebral column does the SC finish?

Back 26

L2

Front 27

Which region of the spinal cord do the nerves exit above their corresponding vertebrae?

Back 27

Cervical area

Front 28

True or False

C1 is the only nerve that does not have a dorsal root

Back 28

True

Front 29

True or False

The spinal cord is mostly supplied by end-artieres

Back 29

True

Front 30

What segments of the SC are particular prone to ischaemia?

Back 30

T4-L1

end-arteries in SC

Front 31

What arteries supply the SC?

Back 31

Single anterior spinal artery and
Two posterior spinal arteries (in pia)

They're branches of the vertebral arteries (sometimes PICA)

Front 32

Most significant radicular artery: Great radicular artery (of Adamkiewicz). What segments does it supply?

Back 32

T9-L1