Neuro - 3 - Spinal Pathways

Front 1

What is within the dorsal horn?

Back 1

Primary Sensory afferent fibers
&
Interneuron cell bodies

Front 2

What is within the ventral horn?

Back 2

Lower Motor efferent cell bodies

In cervical and lumbosacral enlargements, ventral horn has:
Medial portion has fibers that go to dorsal primary ramus towards axial muscles of back
Lateral portion has fibers that go to ventral primary ramus towards muscles of arms and legs

Front 3

What is within the dorsal root ganglion?

Back 3

Collection of sensory afferent cell bodies in the intervertebral foramina

Front 4

Dorsal Primary Ramus

Back 4

Has motor and sensory component

Motor supplies Erector Spinae deep muscles of the back

Sensory supplies skin of central back

Front 5

Ventral Primary Ramus

Back 5

Has a motor and sensory component

Motor supplies the neck, trunk limb muscles

Sensory supplies lateral and anterior cutaneous branches

Front 6

What is the cervical enlargement?

Back 6

Area of spinal cord where nerves of the branchial plexus (arms) come from

Grey matter

Front 7

What is the Lumbosacral enlargement?

Back 7

Area of spinal cord where nerves of the lumbosacral plexus (legs) come from

Grey matter

Front 8

Lamina

Back 8

functional subdivision of the grey matter within the spinal cord

Front 9

Lateral Horn

Back 9

Exists only in T1-L2, S3-S4

Contains pre-ganglionic sympathetic cell bodies whose axons synapse w/ post-ganglionic in paravertebral chain of ganglia

Front 10

Faniculus

Back 10

functional subdivision of the white matter within the spinal cord -- dorsal, ventral, lateral faniculus

Front 11

Fasicles

Back 11

ascending / descending tracts that carry the same info and travel to the same functional areas

Front 12

Spinalthalamic Pathway

Back 12

AKA Anterolateral Tract
Ascending Fasicle

responsible for conveying protopathic sensations to the cerebral cortex

Lateral portion conveys pain and temp

Anterior portion conveys touch and pressure

1* neuron:
cell bodies located in dorsal root ganglion outside spinal cord
fibers located in dorsal horn

2* neuron:
Cell bodies located in dorsal horn
Fibers start in dorsal horn and decussates in spinal cord to lateral faniculus and ascends to VPL of thalamus

Pain and temp fibers decussates immediately at same spinal segment

Touch and pressure decussates after they ascend a few spinal segments

3* neuron:
Cell bodies located in VPL of thalamus
Fibers ascend to post-central gyrus of cerebral cortex

Front 13

Decussation of Pain and Temp Fibers

Back 13

Spinalthalamic Pathway

cell bodies located in the dorsal horn

immediately decussate in the spinal cord across the anterior white commissure,
traverses the lateral faniculus, and then ascends to the VPL of the thalamus

Front 14

Decussation of Touch and Pressure fibers

Back 14

Spinalthalamic Pathway

cell bodies located in the dorsal horn

Fibers ascend a few spinal segments before they decussate across the anterior white commissure,
traverses the anterior faniculus, and then ascends to the VPL of the thalamus

Front 15

Dorsal Column Pathway

Back 15

Ascending Fasicles

responsible for conveying conscious proprioreception to the cerebral cortex like 2-point discrimination, stereognosis, body position sense

1* neuron:
cell bodies are located in dorsal root ganglion outside spinal cord
fibers are located in dorsal faniculus and ascends immediate to medulla
Fibers from upper body travel up Fasiculus Cuneatus (lateral dorsal column)
Fibers from lower body travel up Fasiculus Gracilis (medial dorsal column)

2* neuron:
Cell bodies are located in medulla's Nucleus Cuneatus/Gracilis
Fibers decussate here and ascend up to VPL in Medial Lemniscus tract

3* Neuron:
Cell bodies located in VPL of thalamus
Fibers ascend to post-central gyrus of cerebral cortex

Front 16

Where do fibers of 2-point discrimination decussate?

Back 16

Dorsal Column Pathway

Cell bodies located in medulla's Nucleus Cuneatus/Gracilis

Fibers decussate in dorsal rostal of medulla and ascend to VPL in Medial Lemniscus tract

Front 17

Fasiculus Cuneatus

Back 17

Lateral dorsal column that has ascending proprioceptive fibers originating from upper half of body

Front 18

Fasiculus Gracilis

Back 18

medial dorsal column that has ascending proprioceptive fibers originating from lower half of body

Front 19

What would happen if you had pressure on the dorsal column of a spinal segment

Back 19

Loss of 2-point discrimination from segment down due to its ascent through dorsal column

Pain, temperature and touch would be okay due to decussation to anterolateral segment of spinal cord

Front 20

What would happen if you had injury to only one side of a spinal segment

Back 20

2-point discrimination of ipsilateral side would be affected below spinal segment

pain, temp and touch of contralateral side would be affected below spinal segment

Front 21

Corticospinal Pathway

Back 21

Descending Fasicles

Consists of Lateral (majority) and Anterior (minority) Tract

Lateral Tract:
UMN descends from pre-central gurys through midbrain and pons
Decussates in medulla and travels down in contralateral latera faniculus to synapse with LMN in ventral horn

Anterior Tract:
UMN descends from pre-central gyrus through midbrain, pons and medulla.
Continues descent through Ipsilateral lateral faniculus and decussates in anterior white commisure of spinal cord to synapse with LMN in ventral horn

Front 22

Where does the Lateral Tract of Corticospinal pathway decussate?

Back 22

UMN decussates in pyramidal medulla and descends down through Contralateral lateral faniculus to LMN

Front 23

Where does the Anterior Tract of Corticospinal pathway decussate?

Back 23

UMN descends down Ipsilateral Lateral Faniculus and decussates in anterior white commissure of spinal cord to synapse with LMN

There is no pyramidal decussation

Front 24

What is seen in UMN damage

Back 24

Loss of contralateral control
**Pathological reflexes like Babinski's sign appears
**Spastic Paralysis

Decreased strength
but
Increased muscle tone
Increases stretch reflexes
Mild atrophy

Front 25

What is seen in LMN damage

Back 25

Loss of Ipsilateral control
**Flaccid paralysis

Decreased strength
Decreased muscle tone
Decreased stretch reflexes
Severe Atrophy
Fasciculations (visible twitch)
Fibrillations (not visible rapid, irregular, unsynchronized contraction of muscle fibers)

Front 26

When Babinski's sign is observed, what does it indicate.

Back 26

UMN damage

Front 27

Brown-Sequard Syndrome

Back 27

Hemisection of spinal cord (only one side cut)

Causes
Ipsilateral (to hemisection) spastic muscle paralysis below lesion (Contralateral UMN damage cannot regulate LMN)
Ipsilateral loss of 2-point discrimination
Contralateral loss of pain, temp, touch