Spinal Cord

Question 0

What is the arterial supply of the sp. cord?

Answer 0

branches of the ant. spinal a.
post. spinal a.

(also gets supply from multiple radicular aa.)

Question 1

What is the sp. cord derived from?

Answer 1

embryonic neural tube

Question 2

Where do the ant. & post. spinal aa. branch from?

Answer 2

vertebral arteries

Question 3

The spinal cord extends from the _________ to the _________.

Answer 3

medulla at the foramen magnum; lower border of L1

Question 4

What are the 2 enlargements? What are their functions?

Answer 4

Cervical - innervate upper extremities

Lumbar - innervate lower extremities

Question 5

Conus medullaris

Answer 5

L1 & L2 vertebrae

Question 6

Site for lumbar puncture:

Answer 6

L4-L5 vertebrae

Question 7

Filum terminale

Answer 7

pia mater from the conus medullaris to the coccygeal ligament

Question 8

Cauda equina

Answer 8

lumbosacral roots surrounding the filum terminale

Question 9

How is the sp. cord segmented?

Answer 9

31 pairs of spinal nerves in 31 segments:
8 cervical 
12 thoracic
5 lumbar
5 sacral
1 coccygeal

Question 10

All spinal nerves innervate a single dermatome except?

Answer 10

C1

Question 11

What is referred pain?

Answer 11

convergence of somatic and visceral afferents

Question 12

Spinal nerves exit the _________ via the ____________ (location of ______).

Answer 12

vertebral canal; intervertebral foramina; DRG

Question 13

Spinal cord indentations:

Answer 13

Anterior median fissure
posterior median sulcus/septum
posterolateral sulcus
posterior intermediate sulcus

Question 14

What lies in the ant. median fissure?

Answer 14

ant. spinal artery and vein

Question 15

____________ (entry of dorsal roots)

____________ (exit of ventral roots)

Answer 15

posterolateral sulcus

anterolateral sulcus

Question 16

The ______________ is found in the ______________ only and is the separation of between 2 major ascending tracts

Answer 16

posterior intermediate sulcus; cervical and thoracic

Question 17

What is the largest area of the spinal cord? The smallest?

Answer 17

cervical enlargement

sacral level

Question 18

White matter is subdivided into:

Answer 18

Posterior funiculus (dorsal column)
Lateral funiculus (column)
Anterior funiculus (column)

Question 19

Posterior funiculus:

Answer 19

Ascending somatosensory fibers:

1) Fasciculus gracilis (sacral & lumbar)
2) Fasciculus cuneatus (thoracic & cervical)

Question 20

What is the function of ascending somatosensory fibers?

Answer 20

fine touch
vibration
two-point discrimination
proprioception

Question 21

Lateral funiculus:

Answer 21

Descending tracts to the spinal cord:
lateral corticospinal tract
rubrospinal tract

Question 22

What is the largest and most important tract? What will happen if this tract is lesioned?

Answer 22

lateral corticospinal tract

if lesioned, spastic paralysis will occur on the ipsi lateral side at the spinal cord level

Question 23

The rubospinal tract is a(n) ____________ tract

Answer 23

contralateral

Question 24

The posterior funiculus is a(n) __________ tract.

Answer 24

ipsilateral

Question 25

What will happen if the posterior funiculus is lesioned?

Answer 25

There will be loss of somatosensory sensation on the ipsi side below the level of the lesion

Question 26

Ascending tracts from the spinal cord:

Answer 26

spinothalamic tracts = anterolateral tract | posterior spinocerebellar tract

Question 27

Spinothalamic tracts:

Answer 27

contralateral tract pain, temp., crude touch if lesioned: loss of sensation on the contralateral side

Question 28

Posterior spinocerebellar tract:

Answer 28

``` ipsilateral tract (from spinal cord to cerebellum) stretch, touch and pressure sensation ``` if lesioned: loss of sensation on the ipsilateral side

Question 29

Anterior funiculus:

Answer 29

smaller ascending and descending tracts | crossing of the spinothalamic tracts

Question 30

Gray matter is subdivided into:

Answer 30

dorsal horn ventral horn lateral horn

Question 31

Dorsal horn:

Answer 31

Sensory: receives sensory input mediates synapses gives rise to ascending sensory pathways

Question 33

Ventral horn:

Answer 33

``` Motor: • α motoneurons • γ motoneurons • interneurons • Neurons innervate extrafusal & intrafusal muscle fibers ```

Question 34

Lateral horn:

Answer 34

Intermediolateral cell column (T1-L2/L3) | Thoracolumbar sympathetic outflow (preganglionic)

Question 35

There are ____ cellular laminae

Answer 35

9

Question 36

Dorsal horn: I - VI

Answer 36

All sensory: I - marginal zone (pain & temp) II - substantia gelatinosa (interneurons) III - V - mechanical visceral and noxious stimuli VI - prominent only at enlargements

Question 37

Which laminae give rise to the anterolateral tract?

Answer 37

I, V and some VII

Question 38

Intermediate zone: dorsal VII

Answer 38

Medial: Clarke's nucleus (C8-L3) • gives rise to dorsal spinocerebellar tract Lateral: • Intermediolateral cell column (T1-L2/L3) - preganglionic sympathetic • Sacral autonomic nuclei (S2-S4) - preganglionic parasympathetic

Question 39

Ventral horn:

Answer 39

ventral VII, VIII & IX | • Motor neuronal groups in lamina IX: innervate truncal & limb muscles

Question 40

General functional significance of the spinal cord:

Answer 40

1) receives the primary sensory afferent inputs from the DRG; relays them to the brain stem, cerebellum or the thalamus; may or may not synapse within the spinal cord 2) α & γ motorneurons that innervate extrafusal & intrafusal muscles 3) mediates spinal reflexes 4) intermediolateral cell column from T1 to L2/L3 that gives rise to preganglionic sympathetic fibers; synapse in the paravertebral & prevertebral ganglia 5) preganglionic parasympathetic neurons in S2-S4; synapse in terminal ganglia within walls of the pelvic viscera 6) major sensory & motor ascending and descending tracts run through it

Question 41

Lesions of the spinal cord:

Answer 41

``` dorsal root lesions ventral root lesions spinal cord hemisection (Brown-Sequard syndrome) spinal cord transection syringomyelia ```

Question 42

Dorsal root lesions:

Answer 42

hypesthesia or anesthesia

Question 43

Ventral root lesions:

Answer 43

weakness/flaccid paralysis & atrophy of muscles | involvement of autonomic preganglionic fibers may result in autonomic dysfunction

Question 44

Spinal cord hemisection:

Answer 44

loss of fine touch, vibration and propioception ipsilateral to & below lesion loss of pain & temp. contralateral to & below lesion spastic paralysis ipsi to & below lesion

Question 45

Spinal cord transection:

Answer 45

destruction of ascending and/or descending tracts produces sensory, motor & mixed deficits

Question 46

Syringomyelia:

Answer 46

damage crossing fibers around the central canal