spinal cord lab

Question 1

2. Understand the functional consequence for hemilesions of the cord at different levels (Brown-Sequard syndrome).

Answer 1

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Question 2

Where is the gray/white matter in the spinal cord?

Answer 2

Gray matter on inside, white matter on outside

Question 3

3. Understand the general layout of gray matter in the spinal cord in anterior (or ventral) horn, intermediate gray and the dorsal horn

Answer 3

anterior horn: contains cell bodies of lower motor neurons that innervate skeletal muscle in the limbs and torso. The intermediate gray: contains interneurons as
well as preganglionic sympathetic neurons in thoracic levels. The dorsal horn: contains neurons involved in processing information on pain and temperature.anterior horn: contains cell bodies of lower motor neurons that innervate skeletal muscle in the limbs and torso. The intermediate gray: contains interneurons as
well as preganglionic sympathetic neurons in thoracic levels. The dorsal horn: contains neurons involved in processing information on pain and temperature.

Question 4

Where is the spinal cord enlarged

Answer 4

lumbar and lower cervical levels

Question 5

4. Recognize where along the length of the spinal cord a section is taken from: sacral/lumbar, thoracic, lower cervical, upper cervical. Understand why the cord is enlarged in lumbar and lower cervical levels.

Answer 5

at these levels all innervation necessary for
control of axial muscles and incoming sensory information from lower –lumbar- and upper – lower cervical- extremities comes out of or into the cord at these levels all innervation necessary for
control of axial muscles and incoming sensory information from lower –lumbar- and upper – lower cervical- extremities comes out of or into the cord

Question 6

Characteristics of sacral/lumbar spinal cord

Answer 6

Gray matter is largest, cord appears round,

Question 7

Characteristics of Thoracic spinal cord

Answer 7

White matter appears large, small amount of gray matter, posterior and anterior horns appear small, cord is round

Question 8

Characteristics of lower cervical spinal cord

Answer 8

Large anterior horn, large amount of white matter, cord is oval,

Question 9

Characteristics of upper cervical spinal cord

Answer 9

Cord is round, anterior horn is smaller and posterior horn is larger than lower spinal cord,

Question 10

6. Understand the flow of information from sensory receptors in the skin and muscle to brain stem and spinal cord. Ie. Posterior column-medial lemniscus pathway

Answer 10

Sensory endings in skin/muslces transmit touch, vibration and changes in muscle tension/joint angles to cell bodies in dorsal root ganglion > sensory info sent along axon through spinal cord to synapse with second order neurons in spinal cord or brainstem.

Question 11

Understand the function of the axon collaterals originating in the dorsal (posterior) root ganglia (PRG) that terminate in spinal cord.

Answer 11

These play a role in reflexes (ie. Knee jerk action)

Question 12

Understand the function of axons originating in the neurons in the PRG that ascend and terminate in brain stem.

Answer 12

Carry sensory and proprioceptive info from skin/muscles to nucleus in brainstem, then to the thalamus

Question 13

Function of posterior column-medial lemniscus system

Answer 13

1. carries information on vibration and discriminative touch from receptors in the skin. 2. Carries proprioception (the sensation conveying information on the position of your limbs) info from muscles and tendons

Question 14

Name the posterior fasciculus subdivision and where they are located relative to other structures in spinal cord

Answer 14

fasciculus gracilis (FGr) and fasciculus cuneatus (FCu). Both are in the posterior spinal cord, in the posterior column (white matter). FGr is more medial and Fcu is more lateral (next to the dorsal horn)

Question 15

7.What information do the fasciculus gracilis (FGr) and fasciculus cuneatus (FCu) carry

Answer 15

fasciculus gracilis (FGr): contains collection of axons from dorsal root ganglion transmitting sensory info from lower limbs (below T6) to second order neurons in brainstem or spinal cord. fasciculus cuneatus (FCu): contains collection of axons from dorsal root ganglion transmitting sensory info from upper limbs (above T6) to second order neurons in brainstem or spinal cord

Question 16

In representative sections of the spinal cord at different levels, identify the posterior fasciculus, and its two subdivisions

Answer 16

1. sacral: Gracilis only. 2. Lumbar: gracilis only. 3. Thoracic: gracilus( large and next to posterior median sulcus) and cuneatus ( small, lateral). 4. Lower cervical: gracilis (small) and cuneatus (large). 5. gracilis (small) and cuneatus (large)

Question 17

Do the posterior fasciculus fibers ascend ipsilaterally or contralaterally in the spinal cord? Brain stem?

Answer 17

ipsilateral in spinal cord, contralateral in brainstem (after synapsing at the nucleus gracilis or cuneatus, the fibers cross the the contralateral side as the internal arcuate fibers, then continue as the medial lemniscus)

Question 18

Understand the effects of lesions of posterior fasciulus at different sections of spinal cord

Answer 18

Below T6: ipsilateral loss of proprioception, discriminative touch and vibratory sense in lower extemities below lesion. Above T6: ipsilateral loss of proprioception, discriminative touch and vibratory sense in both lower and upper extemities below lesion.

Question 19

Function of anterolateral system

Answer 19

carries information on temperature and pain

Question 20

8. In reference to the pathways of the anterolateral system, understand the ascending flow of information from pain and temperature sensory receptors

Answer 20

Sensory endings in skin > cell body in posterior root ganglion > axon synapses ipsilaterally on second order neurons in the dorsal horn at the level of the substantia gelatinosa or nucleus proprius (both are in the dorsal horn at all levels of spinal cord) > second order axons cross midline as the anterior white commissure > axons ascend along anterolateral tract > spinothalamic tract > synapses at thalamus in ventral posterior lateral nucleus (contralateral to dorsal root ganglion of origin)

Question 21

9. In representative sections of the spinal cord at different levels, identify dorsolateral tract (Lissauer’s tract), the substantia gelatinosa and the location of the anterolateral tract.

Answer 21

1. Dorsolateral tract is always between the dorsal horn and the border of the spinal cord. 2. Substantia gelatinosa is always in the dorsal horn (lighter color), dorsal to the nucleus proprius. 3. Anterolateral tract is always anterior and lateral to the anterior horn

Question 22

Understand the effects of lesions at different levels of the anterolateral tract

Answer 22

A lesion on one side of the spinal cord at the anterolateral tract will cause a loss of pain and temperature sensation two levels caudal (inferior) to the lesion, on the contralateral side.

Question 23

Effect of unilateral lesion of substantia gelatinosa and nucleus proprius?

Answer 23

loss of pain and temperature sensation below the lesion, on theipsilateral side.

Question 24

Function of corticospinal tract

Answer 24

carry commands from upper motor neurons in

motor cortex to lower motor neurons in spinal cord to control muscle movement

Question 25

Lateral corticospinal tracts pathways

Answer 25

axon from cell in motor cortex > decussate (cross midline) in pyramids at level of medulla in brainstem > lateral corticospinal tract > synapse on lower motor neurons in the lateral aspect of the anterior horn, contralateral to the side of the upper motor neuron.

Question 26

Anterior corticospinal tract pathway

Answer 26

axon from cell in motor cortex > anterior corticospinal tract (in brainstem)

Question 27

10. Understand the symptoms occurring after damage of either upper motor neurons or lower motor neurons

Answer 27

Upper motor neurons (cortex or corticospinal tract): hyperreflexia, spasticity, loss of superficial abdominal reflexes and the Babinski sign. Lower motor neurons (btw anterior horn and muscle): flaccid paralysis on ipsilateral side

Question 28

Identify the location of the lateral and anterior (or medial) corticospinal tracts in stained sections of the spinal cord

Answer 28

Lateral corticospinal tract: lateral, btw anterior and posterior horn in white matter(but more towards posterior horn), dorsal to the anterolateral system. Anterior corticospinal tract: small, anterior, next to the anterior median fissure in the white matter.

Question 29

Which muscle groups are controlled by axons in the lateral vs the anterior corticospinal tract?

Answer 29

Lateral: distal muscles (arms, hands, lower limbs, etc). Anterior: the rest

Question 30

Where are the intermediolateral cell columns located

Answer 30

At thoracic and the upper two or three lumbar levels of the cord

Question 31

What is the intermediolateral cell column

Answer 31

The cell bodies of the preganglionic sympathetic neurons that innervate sympathetic ganglia are found in the intermediolateral cell columns

Question 32

11. Know the location of neuron cell bodies for preganglionic parasympathetics

Answer 32

Intermediate zone