Chapter 19 Spinal Cord Flashcards
filum terminale
bundle of connective tissue and glia that connects the end of the cord to the coccyx
cauda equina
horselike tail
long roots exiting the lumbosacral vertebral column
dorsal root
contains sensory axons, brings information into the spinal cord
spinal nerves
carry all of the motor, autonomic, and sensory axons of a single spinal segment
dorsal rami
innervate the paravertebral muscles, posterior parts of the vertebrae, and overlying cutaneous areas
ventral rami
innervate the skeletal, muscular, and cutaneous areas of the limbs and of the anterior and lateral trunk
propriospinal
neurons that begin and end within the spinal cord
adjacent to gray matter
tract cells
cells with long axons that connect the spinal cord with the brain
dorsal horn
primarily sensory, contains endings and collaterals of first-order sensory neurons, interneurons, and dendrites and somas of tract cells
Nucleus Dorsalis
Clarke’s Column
receives proprioceptive info
relays unconscious proprioceptive info to cerebellum
from T1-L3 anterior to dorsal horn
lateral horn
contains cell bodies of preganglionic sympathetic neurons
present only at T1-L2
ventral horn
consists of LMN cell bodies
stepping pattern generators
adaptable neural networks that produce rhythmic output
contribute to stepping by activating LMN, eliciting alternating flexion and extension at the hips and knees
crossed extension reflex
interneuronal circuit that prevents falling when one is standing and lower limb is abruptly withdrawn by adjusting the muscle activity in the stance limb
reciprocal inhibition
decreases activity in an antagonist when an agonist is active, allowing the agonist to act unopposed
recurrent inhibition
inhibition of agonists and synergies, with disinhibition of antagonists
Renshaw cells produce recurrent inhibition
sacral spinal cord controls
urination, bowel function, and sexual function
reflexive bladder function requires
afferents
T1-L2 and S2-S4 cord levels
somatic, sympathetic, and parasympathetic efferents
psychogenic process
involves erotic thoughts and is mediated by L1-L2 sympathetic fibers
reflexogenic erection/engorgement and lubrication results from
direct sensory stimulation of the genitals and is mediated by S2-S4 afferents and S2-S4 parasympathetic fibers
what elicits ejaculation and contraction of pelvic floor
sympathetic nerves L1-L2 and pudendal nerve with cell bodies in S2-S4
vertical tract lesion
results in loss of communication to and from the spinal levels below the lesion
peripheral region lesions
produce deficits in the distribution of a peripheral nerve
-altered or lost sensation in peripheral nerve distr.
-decrease or loss of muscle power in pn distri.
-no vertical tract signs
-decreased or lost phasic stretch reflex
spinal region segmental signs
occurs when a spinal segment, nerve root, and/or spinal nerve is compromised
-altered or lost sensation in a dermatome
-decreased or lost muscle power in a myotome
-decreased or lost phasic stretch reflex
-UMN signs: loss of muscle power, spasticity, hypertonia, babinski sign, clonus
Anterior cord syndrome
caused by disruption of blood flow to anterior spinal artery
interferes with nociceptive and temp sensation and motor control
Central cord syndrome
occurs at cervical level due to trauma
small lesion: loss of nociceptive and temp info occurs at the level of the lesion
large lesion: additionally impair upper limb motor function
Brown-Sequard Syndrome
occurs at hemisection of cord
segmental losses are ipsilateral includes loss of LMN and all sensations, voluntary motor control, conscious proprioception, and light touch are lost ipsilaterally
contralaterally: loss of nociception and temperature
Cauda equina syndrome
damage to lumbar or sacral spinal roots causing sensory impairment and flaccid paresis or paralysis of lower limb muscles, bladder, and bowels
Tethered cord syndrome
spinal cord becomes attached to surrounding structures during early development
low back and lower limb pain, difficulty walking, scoliosis, issues with bowel/bladder control, foot deformities
associated with spina bifida
Traumatic SCI is due to
crush, hemorrhage, edema, and infarction
spinal shock
immediately after injury functions are depressed or lost due to leakage of potassium into extracellular matrix
below lesion: paralysis, loss of sensation, somatic reflexes are lost, autonomic reflexes are lost, blood pressure is impaired, control of sweating lost
reflexes mediated by S2 to S4
clitoroanal reflex
bulbocavernosus reflex
anal reflex
people with lesions above C4
can’t breathe independently
paraplegia
damage to spinal cord below cervical level, sparing arm function
complete injury
lack of sensory and motor function in the lowest sacral segment
incomplete injury
preservation of sensory and/or motor function in the lowest sacral segment
Neurologic Level
the lowest, most caudal, level with normal sensory and motor function bilaterally
4 neurologic segments: right sensory, left sensory, right motor, left motor
ASIA classification form
evaluates neurologic level in SCI
28 bilateral points are tested with a safety pin
lesions above T6 result in 3 dysfunctions
orthostatic hypertension
poor thermoregulation
autonomic dysreflexia
autonomic dysreflexia
medical emergency with SCI above T6
causes sympathetic overactivity that constricts blood vessels causes abrupt increase in blood pressure
-pale skin, sweating, pounding headache, reduced heart rate
poor thermoregulation
interferes with the ability to maintain homeostasis
orthostatic hypotension
20mm Hg fall in systolic bp and 10mm Hg fall in diastolic bp or greater than 20 bpm increase in heart rate within 3 min after getting up
Barriers to regeneration in SCI
inhibitory molecules on oligodendrocytes
impenetrable glial scars
decreased rate of growth in mature neurons
secondary changes in SCI
bleeding, edema, ischemia, pain, and inflammation
highest rate of recovery with SCI
people with incomplete paraplegia
complications after SCI
UTI, spasticity, chills and fever, contractures, penumonia, decubiti, autonomic dysreflexia, ossification
locomotor training
using repetitive motions and epidural stimulation to elicit activity-dependent neuroplasticity
radiculopathy
lesion of a nerve root
avulsion or severance of dorsal root causes
loss of sensation in the dermatome
avulsion or severance of ventral root causes
deprives the muscles in its myotome of motor innervation resulting in muscle atrophy and fibrillation
traumatic avulsion of C5 and C6 motor nerve roots causes
Erb’s Palsy
result of forceful separation of the head and shoulder
Klumpke’s paralysis
due to avulsion of motor roots of C8 to T1
results in paralysis and atrophy of the hand intrinsic muscles and long flexors and extensors of fingers
sciatica
pain radiating from the lower back down to the lower limb along the path of the sciatic nerve
Multiple Sclerosis
demyelination of the CNS
Lhermitte’s sign, numbness, paresthesia
Lhermitte’s sign
radiation of a sensation similar to electric shock down the back or limbs, elicited by neck flexion
Spinal region tumors
tumors outside dura or in subarachnoid space may compress spinal cord, nerve roots, spinal nerves, or their blood supply
pain aggravated by coughing or sneezing
vertebral canal stenosis
narrowing of vertebral canal results in compression of neural and vascular structures
cervical stenosis
narrowing of intervertebral foramina compresses spinal nerves resulting in dermatomal distribution of abnormal sensations, pain, numbness, weakness and atrophy in upper limbs
causes cervical spondylotic myelopathy
cervical spondylotic myelopathy
affected somatosensation and motor function in both the upper and lower limbs
axial neck pain and or scapular pain
abnormal gait
incoordination
babinski sign
clonus
lumbar stenosis
produces lower limb and lower back pain that may be aggravated by walking and improves with rest
syringomyelia
progressive & congenital but may occur to trauma or tumor
a syrinx (CSF fluid-filled cavity) develops in the spinal cord in cervical region
loss of sensitivity to nociceptive signals and temp stimuli, paresis and muscle atrophy
Red Flags for the Spinal Region
bilateral loss of somatosensation
incoordination
decreased muscle power
spasticity
muscle hypertonia
Babinski’s sign
clonus
difficulty urinating/deficating
saddle anesthesia
low back pain
unilateral/bilateral sciatica
lower limb paresis and sensory deficits
lost lower limb reflexes
pain in buttock, lower limb, and foot while walking that diasappears after rest
decreased pulse in lower limb
cyanosis (bluish color of skin)
