Spinal cord 2 Flashcards
Which pathway transmits afferent nociceptive input to the brain?
a. medial lemniscal system
b. anterolateral system
c. corticospinal tract
d. Lissauer tract
b. anterolateral system
The ____________ tract transmits motor impulses.
corticospinal tract
The __________ tract is an intermediary pathway that relays sensory input in the spinal cord.
Lissauer
The _______ tract transmits fine touch, proprioception, vibration, and pressure
medial lemniscal system (dorsal column)
The anterolateral system is a
three-neuron sensory pathway
The anterolateral system transmits
pain
temperature
Crude touch
itch
tickle
sexual sensation
The anterolateral system consists of
smaller, myelinated and nonmyelinated, slower conducting fibers
In the anterolateral system, ____________ is not present
two-point discrimination
The anterolateral system transmits
sensory information 1/2 to 1/3rd as fast as the dorsal column
Nociceptors transmit
pain
Mechanoreceptors transmit
pressure, crude touch, tickle, itch, and sexual sensation
Thermoreceptors transmit
temperature
The first-order neurons of the anterolateral system contain
two nerve fiber types:
a-delta
c-fibers
A-delta fibers are
“first” pain, mechanoreceptors
C-fibers are
“slow” pain, polymodal nociceptors
The first order neurons of the anterolateral system may ascend or descend
1-3 levels on the ipsilateral side in the Lissauer tract before synapsing with the second-order neruon
Pain neurons in the anterolateral tract synapse with the second-order neuron in the
substantia gelatinosa- Rexed lamina 2
Primary pain neurons of the anterolateral tract also may synapse with the second-order neuron in the
dorsal horn laminae 1,4,5 and 6
Second-order neurons of the anterolateral system synapse with third-order neurons in the
reticular activating system and the thalamus
Second-order neurons cross
to the contralateral side of the spinal cord then ascend towards the brain via two pathways
What two pathways do second order neurons of the anterolateral system use to ascend towards the brain?
lateral spinothalamic tract
anterior spinothalamic tarct
The lateral spinothalamic tract transmits
pain and temperature
The anterior spinothalamic tract transmits
crude touch and pressure
Injury to the corticospinal tract above the level of decussation in the medulla will result in: (select 2)
a. flaccid paralysis
b. contralateral paralysis
c. ipsilateral paralysis
d. spastic paralysis
b. contralateral paralysis
d. spastic paralysis
The corticospinal tract carries
motor signals from the cerebral cortex to the muscles of the body
If there is an injury to the corticospinal tract above the level of decussation then the patient will experience
spastic paralysis on the contralateral side
If there is an injury to the corticospinal tract below the level of decussation, then the patient will experience
flaccid paralysis on the ipsilateral side
The _____________ is the most important motor pathway
corticospinal tract
The corticospinal tract is also called the
pyramidal tract
All the other motor pathways outside of the corticospinal tract are known collectively as the
extrapyramidal tract
The upper motor neurons begin in the _________________ and synapse with the lower motor neurons in the _________________
cerebral cortex and synapse with the lower motor neurons in the ventral horn of the spinal cord
Examples of upper motor neuron diseases include
cerebral palsy & ALS
Upper motor neuron injury below the level of decussation leads to
spastic ipsilateral paralysis
Upper motor neuron injury above the level of decussation leads to
spastic contralateral paralysis
Lower motor neurons begin in the ___________ and end at the ___________
ventral horn and end at the neuromuscular junction
A lower motor neuron injury results in
ipsilateral paralysis
Lower motor neuron injuries present with
impaired reflexes and flaccid paralysis
The primary function of the corticospinal tract includes
voluntary fine motor control to the limbs and coordination of posture
This test assesses the integrity of the corticospinal tract
The Babinski test
The lower motor neurons pass messages from the
spinal cord to the muscles
Where does the upper motor neuron begin and end?
it begins in the cerebral cortex and ends in the ventral horn of the spinal cord
Which findings are MOST likely to occur during the acute phase of spinal cord transection at C7?
a. autonomic hyperreflexia and hypothermia
b. bradycardia and hypothermia
c. tachycardia and hypotension
d. hypothermia and tachycardia
B. bradycardia and hypothermia
the patient with an acute C7 transection will experience neurogenic shock
Acute spinal cord injury is most commonly caused by
a motor vehicle accident, fall, assault, or sports injury
The most common site of spinal cord injury is
C7
Complete spinal cord injury damages the
upper motor neuurons
With a complete spinal cord injury, spinal cord reflexes are _________ but they __________
lost during the acute phase (flaccid paralysis) but they return later (spasticity)
SCI can cause _______ shock
neurogenic
Neurogenic shock presents as
hypotension, bradycardia, and hypothermia with pink, warm extremities
The major causes of morbidity and mortality in patients with cervical and upper thoracic lesions are
ineffective alveolar ventilation and the inability to clear pulmonary secretions
What drug should be avoided in patients with spinal cord injury?
succinylcholine!
The higher the injury, the greater degree of
hemodynamic instability
Neurogenic shock can last
1-3 weeks
Describe how bradycardia and reduced inotropy in SCI occurs.
impairment of cardiaccelerator fibers (T1-T4)–> unopposed cardiac vagal tone
Describe how hypotension occurs in SCI.
decreased SNS tone–> vasodilation–> venous pooling–> decreased CO and BP
Describe how hypothermia occurs in SCI.
impairment of sympathetic pathways from the hypothalamus to blood vessels–> inability to vasoconstrict or shiver–> hypothermia
