spinal cord lab Flashcards
- Understand the functional consequence for hemilesions of the cord at different levels (Brown-Sequard syndrome).
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Where is the gray/white matter in the spinal cord?
Gray matter on inside, white matter on outside
- Understand the general layout of gray matter in the spinal cord in anterior (or ventral) horn, intermediate gray and the dorsal horn
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.
Where is the spinal cord enlarged
lumbar and lower cervical levels
- 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.
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
Characteristics of sacral/lumbar spinal cord
Gray matter is largest, cord appears round,
Characteristics of Thoracic spinal cord
White matter appears large, small amount of gray matter, posterior and anterior horns appear small, cord is round
Characteristics of lower cervical spinal cord
Large anterior horn, large amount of white matter, cord is oval,
Characteristics of upper cervical spinal cord
Cord is round, anterior horn is smaller and posterior horn is larger than lower spinal cord,
- 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
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.
Understand the function of the axon collaterals originating in the dorsal (posterior) root ganglia (PRG) that terminate in spinal cord.
These play a role in reflexes (ie. Knee jerk action)
Understand the function of axons originating in the neurons in the PRG that ascend and terminate in brain stem.
Carry sensory and proprioceptive info from skin/muscles to nucleus in brainstem, then to the thalamus
Function of posterior column-medial lemniscus system
- 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
Name the posterior fasciculus subdivision and where they are located relative to other structures in spinal cord
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)
7.What information do the fasciculus gracilis (FGr) and fasciculus cuneatus (FCu) carry
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
In representative sections of the spinal cord at different levels, identify the posterior fasciculus, and its two subdivisions
- 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)
Do the posterior fasciculus fibers ascend ipsilaterally or contralaterally in the spinal cord? Brain stem?
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)
Understand the effects of lesions of posterior fasciulus at different sections of spinal cord
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.
Function of anterolateral system
carries information on temperature and pain
- In reference to the pathways of the anterolateral system, understand the ascending flow of information from pain and temperature sensory receptors
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)
- 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.
- 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
Understand the effects of lesions at different levels of the anterolateral tract
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.
Effect of unilateral lesion of substantia gelatinosa and nucleus proprius?
loss of pain and temperature sensation below the lesion, on theipsilateral side.
Function of corticospinal tract
carry commands from upper motor neurons in
motor cortex to lower motor neurons in spinal cord to control muscle movement
Lateral corticospinal tracts pathways
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.
Anterior corticospinal tract pathway
axon from cell in motor cortex > anterior corticospinal tract (in brainstem)
- Understand the symptoms occurring after damage of either upper motor neurons or lower motor neurons
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
Identify the location of the lateral and anterior (or medial) corticospinal tracts in stained sections of the spinal cord
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.
Which muscle groups are controlled by axons in the lateral vs the anterior corticospinal tract?
Lateral: distal muscles (arms, hands, lower limbs, etc). Anterior: the rest
Where are the intermediolateral cell columns located
At thoracic and the upper two or three lumbar levels of the cord
What is the intermediolateral cell column
The cell bodies of the preganglionic sympathetic neurons that innervate sympathetic ganglia are found in the intermediolateral cell columns
- Know the location of neuron cell bodies for preganglionic parasympathetics
Intermediate zone
