Spinal Cord Flashcards
How many spinal nerves are there?
- 31 spinal nerves total
- 8 cervical
- 12 thoracic
- 5 lumbar
- 1 coccygeal
Where do nerves C1-C7 exit?
Above the corresponding vertebra
Where do all other spinal nerves exit?
Below corresponding vertebra
What is Vertebral disc herniation?
Nucleus pulposus herniates through anulus fibrosus
Where does disc herniation usually occur?
Posterolaterally at L4-L5 or L5-S1
Where does the spinal cord extend to?
Lower border of L1-L2 vertebrae
Where does the Subarachnoid space extend to?
Lower border of S2 vertebra
Where is a lumbar puncture usually performed?
B/w L3-L4 or L4-L5
(level of cauda equina)
What is the goal of a lumbar puncture?
Obtain a sample of CSF w/o damaging the SC
What do the Dorsal columns control?
Pressure, vibration, touch & proprioception
What are the 2 dorsal columns?
Fasciculus cuneatus (UE)
Fasciculus gracilis (LE)
What are the 3 spinal arteries?
2 Posterior & 1 Anterior
What do the Lateral spinothalamic tracts control?
Pain & temperature sense
What are the Intermediate horn sympathetics?
T1-L2/L3
What do the Anterior spinothalamic tracts control?
Crude touch & pressure sense
What do the Lateral corticospinal tracts control?
Voluntary motor
What is the tract of the Dorsal column?
Medial leminiscal pathway
What is the 1st order neuron of the Dorsal column?
Sensory nerve ending→ cell body in dorsal root ganglion→ enters SC, ascending ipsilaterally in dorsal column
What is synapse 1 for Dorsal columns?
Ipsilateral nucleus cuneatus or gracilis (medulla)
What is the 2nd order neuron of the Dorsal column?
Decussates in medulla→ ascends contrallaterally in medial lemniscus
What is synapse 2 for Dorsal columns?
VPL (thalamus)
What is the 3rd order neuron for Dorsal columns?
Sensory cortex
What is the 1st order neuron of the Spinothalamic tract?
Snesory nerve ending (A delta & C fibers) (cell body in dorsal root ganlion)→ enters SC
What is the synapse 1 of the Spinothalamic tract?
Ipsilateral gray matter (SC)
What is the 2nd order neuron of the Spinothalamic tract?
Decussates at anterior white commissure→ ascends contralaterally
What is the synapse 2 for the Spinothalamic tract?
VPL (thalamus)
What is the 3rd order neuron for the Spinothalamic tract?
Sensory cortex
What is the 1st order neuron of the Lateral corticospinal tract?
UMN: cell body in 1° motor cortex→ descends ipsilaterally (through internal capsule) until decussating at cuadal medullar (pyrimdal decussation)→ descends contralaterally
What is the synapse 1 for the Lateral corticospinal tract?
Cell body of anterior horn (SC)
What is the 2nd order neuron for the Lateral corticospinal tract?
LMN: leaves SC
What is the synapse 2 for the lateral corticospinal tract?
NMJ
What happens in a Lower motor neuron lesion?
- Everything lowered
- Less muscle mass
- Dec muscle tone
- Dec reflexes
- Downgoing toes
What happens in an Upper motor neuron lesion?
Everything up (tone, DTR, toes)
What is Fasiculation?
Muscle twitching
When is a + Babinski sign considered normal?
In infants
What are the signs in an UMN lesion?
- Weakness
- Inc reflexes
- Inc tone
- Babinski
- Spastic paralysis
- Clasp knife spasticity
What are the signs in an LMN lesion?
- Weakness
- Atrophy
- Fasiculations
- Dec reflexes
- Dec Tone
- Flaccid paralysis
What are the characteristics of Poliomyelitis & Werding-Hoffman dz?
- LMN lesions only
- Due to destruction of anterior horns
- Flaccid paralysis
What are the characteristics of Multiple sclerosis?
- Scanning speech
- Intention tremor
- Nystagmus
What region of the SC does Mutliple sclerosis effect?
- Mostly white matter of cervical region
- Random & asymmetric lesions
What are the characteristics of Amyotrophic lateral sclerosis (ALS)?
Combined UMN & LMN deficits w/ no sensory, cognitiev or oculomotor deficits
What can cause ALS?
Defect in superoxide dismutase 1
How does ALS present?
Fasiculations w/ eventual atrophy
progressive & fatal
What is the tx for ALS?
Riluzole tx modestly inc survival by dec presynaptic glutamate release
What is ALS also know as?
Lou Gehring’s dz
What are the characteristics of Complete occlusion of anterior spinal artery?
- Spares dorsal columns & Lissauer’s tract
- Upper throracic ASA territory is a whatershed area, as artery of Adamkiewiez supplies ASA below ~T8
What causes Tabes dorsalis?
3° syphilis
What does Tabes dorsalis result from?
Demyelination of dorsal columns & roots→ impaired sensation & proprioception & progressive sensory ataxia (inability to sense or feel legs)
What is Tabes dorsalis assoc w/?
- Charcot’s joints
- Shooting pain
- Argyll Robertson pupils
What are Argyll Robertsons pupils?
Small bilateral pupils that further constrict to accommodation but not to light
What will Tabes dorsalis demonstrate on PE?
Absence of DTR’s & + Romberg
What are the characteristics of Syringomyelia?
Syrinx expands & damages anterior white commissure of spinothalamic tract (2nd order neurons)→ bilateral loss of pain & temp sensation (us. C8-T1)
Can expand & affect other tracts
What can Syringomyelia be seen w/?
Chiari I malformations
What are the characteristics of Vit B12 or Vit E def?
Subacute combined degeneration–demyelinations of dorsal columns, lateral corticospinal tracts & spinocerebellar tracts; ataxic gait, paresthesia, impaired position & vibration sense
What causes Poliomyelitis?
Poliovirus
How does poliovirus infect the body?
Fecal-oral transmission
Where does poliovirus replicate?
Oropharynx & SI before spreading via the BS to the CNS
What does poliovirus infection cause?
Destruction of cells in anterior horn of SC (LMN death)
Poliomyelitis
What are the LMN lesions signs in Poliomyelitis?
- Weakness
- Hypotonia
- Flaccid paralysis
- Atrophy
- Fasciculations
- Hyporeflexia
- Muscle atrophy
What are the signs of infection in Poliomyelitis?
- Malaise
- Headache
- Fever
- Nausea
What are the findings in Poliomyelitis?
CSF w/ inc WBCs w/ slight elevation of protein (w/ no change in CSF glucose)
Where can the poliovirus be recovered?
Stool or throat
What is Werding-Hoffman dz?
Cogenital degeneration of anterior horns of SC→ LMN lesion. “Floppy baby” w/ marked hypotonia & tongue fasciculations
What is the infantile type of Werdnig-Hoffman dz?
Median age of death of 7 months
AR inheritance
What causes Friedreich’s ataxia?
AR trinucelotide repeat disorder (GAA) in gene that encodes frataxin. Leads to impairment in mito functioning
What are the characteristics of Friedreich’s ataxia?
- Staggering gait
- Frequent falling
- Nystagmus
- Dysarthria
- Pes Cavus
- Hammer toes
How does Friedreich’s ataxia present?
In childhood w/ kyphoscoliosis
What is the COD in Friedreich’s ataxia?
Hypertrophic cardiomyopathy
What is Brown-Séquard synd?
Hemisection of SC
What are the findings in Brown-Séquard synd?
- Ipsi UMN signs BELOW level of lesion
- Ipsi loss of tactile, vibration, proprioception sense BELOW
- Contra pain & temp loss BELOW
- Ipsi loss of all sensation AT level of lesion
- Ipsi LMN signs AT level
What happens if the lesion in Brown-Séquard is above T1?
Pt may present w/ Horner’s synd d/t damage of sympathetic ganglion
What is Horner’s syndrome?
Sympathetctomy of face: Ptosis, Anhidrosis (& flushing of affected side of face) & miosis
What is Ptosis?
Slight drooping of eyelid: superior tarsal muscle
What is Anhidrosis?
Absence of sweating
What is rubor?
Flushing
What is Horner’s synd assoc w/?
Lesion of SC above T1
(Pancoast tumor, Brown-Séquard synd, late-stage syringomyelia)
Where does the 3 neuron oculosympathetic pathway project?
Hypothalamus→ intermediolateral column of the SC→ superior cervical ganglion→ pupil, sm of the eyelids & sweat glands of the foreheard & face
What is the landmark of the C2 dermatome?
Posterior half of a skull “cap”
What is the landmark of the C3 dermatome?
High turtleneck shirt
What is the landmark of the C4 dermatome?
Low-collar shirt
What is the landmark of the T4 dermatome?
At the nipple
What is the landmark of the T10 dermatome?
At the umbilicus (important for early appendicitis pain referral)
What is the landmark of the L1 dermatome?
At the inguinal ligament
What is the landmark of the L4 dermatome?
Includes the kneecaps
What are the landmarks of the S2, S3, S4 dermatomes?
Erection & sensation of penile & anal zones
What is the clinical reflex of the Biceps?
C5 nerve root
What is the clinical reflex of the Triceps?
C7
What is the clinical reflex of the Patella?
L4 nerve root
What is the clinical reflex of the Achilles?
S1 nerve root
What is the clinical reflex of the Babinski?
- Dorsiflexion of the big toe & fannin of other toes
- Sign of UMN lesion
- Normal reflex in 1st year of life
What are Primitive reflexes?
CNS reflexes that are present in a healthy infant, but are absent in a neurologically intact adult
When do primitive reflexes disappear?
1st year of life
What are primitive reflexes inhibited by?
Mature/developing frontal lobe
When will primitive reemerge in adults?
Following frontal lobe lesions→ loss of inhibition of these reflexes
What is the Moro reflex?
“Hang on for life” reflex
Abduct/extend limbs when startld & then draw together
What is the Rooting reflex?
Movement of head toward one side if cheek or mouth is stroked (nipple seeking)
What is the Sucking reflex?
Sucking response when roof of mouth is touched
What is the Palmar reflex?
Curling of fingers if palm is stroked
What is the plantar reflex?
Dorsiflexion of large toe & fanning of other toes w/ plantar stim (Babinski sign)
What is the Galant reflex?
Stroking along one side of the spine while newborn is in vental supension (face down) causes lateral flexion of lower body toward stim side
