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SF2 - Test 2 > Egleton - Descending Spinal Cord Pathways > Flashcards

Egleton - Descending Spinal Cord Pathways Flashcards

1
Q

Parasympathetic vs Sympathetic

A

Parasympathetic - Rest & Digest

Originate: Brain Stem and Sacral Cord

Ganglia: Near Target

Long Pre, Short Post

Sympathetic - Fight or Flight

Originate: Thoraco-Lumbar (T1-L3)

Ganglia: Near Spinal Cord

Short Pre, Long Post

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2
Q

Terminus for Autonomic Nervous System fibers?

A

Intermediolateral Nucleus

Sympathetic: T1-L2

Parasympathetic: S2-S4

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3
Q

Referred Pain

A

Consequence of convergence of visceral and somatic pain fibers in given dorsal root on same spinothalamic tract.

Area corresponds to dermatome innervated by spinal segment to which the visceral afferents projects.

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4
Q

Corticospinal Tract

Origin?

Role?

A

“Great Voluntary Motor Pathway”

40% of fibers take origin from Primary Motor Cortex in the Precentral Gyrus

Also contributions from premotor cortex, somatic sensory cortex, parietal lobe, cingulate gyrus, contributions from

Coordinates how muscles move

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5
Q

Primary Motor Cortex

Arrangement?

A

Somatotropic, similar to motor cortex

Brodmann Area 4, homongulus

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6
Q

Path of Corticospinal Tract?

Forms what?

Decussates?

A

Starts in Primary Motor Cortex

Descends through the corona radiate and internal capsule to reach brainstem

Continues through the crus of the midbrain and the basilar pons to reach the medulla oblongata

Forms the Pyramid

85% fibers Decussates at Pyramidal Decussation, forms Lateral Corticospinal Tract (remaining form Anterior Corticospinal Tract)

15% Decussate at origin of LMN

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7
Q

Descending Motor Pathways and Motor Neurons:

Upper Motor Neuron (UMN) vs Lower Motor Neuron (LMN)

A

Upper Motor Neuron: Motor neurons projecting from the Cortex to the Spinal Cord or Brain Stem

Form synapses onto LMN in Anterior Horns of Central Grey in Spinal Cord or Brain Stem

Lower Motor Neuron: Axons project from CNS via Anterior Spinal Roots in Spinal Cord or via Cranial Nerves to muscle cells

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8
Q

Indirect Corticospinal Pathways:

Rubrospinal

Tectospinal

Vestibulospinal

A

Regulate background activity against which the cortiospinal pathway exerts its influence

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9
Q

Rubrospinal tract

Origin?

Decussates?

Travels Down?

Function?

A

Origin: Red Nucleus of Brain Stem

Decussates: Ventral Tegmentum

Descends: Lateral Column

Function: Integrates information, coordinates automatic movements (locomotion)

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10
Q

Anterior Grey Horn

Intrinsic muscles of hand and foot?

Diaphragm?

A

Each motor neuron column in the Anterior Horn supplies muscles having similar functions.

Trunk = Medial

Extensors Anterior to Flexors

Retrodorsolateral Nucleus devoted to hand/foot

Central Nucleus supplies Diaphragm

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11
Q

What is a unique property of corticomotoneuronal fivers of the Lateral Column Spinothalamic Tract?

What can be the result of a lesion in this area?

A

Fractionation - small groups can be selectively activated

Results in skilled movements

- - -

Damage to corticomotorneural fibers = loss of skilled movement, hard to recover

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12
Q

Types of Motor Neurons:

Alpha vs Gamma

A

Alpha = Main force generation

Gamma = Regulate Sensitivity

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13
Q

Renshaw Cells

A

Feedback Cells

Involved in co-contraction of like muscles, and inhibition of their antagonists

Also attenuate alpha motorneuron activity

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14
Q

Excitatory Internuncials

Ia Inhibitory Internuncials

A

Help recruit additional motor neurons

Antagonist Inactivation – first neurons activated during voluntary movement

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15
Q

UMN Lesion vs LMN Lesion

(not table, just define)

A

UMN = Lesion in pathway prior to synapse in the anterior horn

LMN = Lesion anywhere between the muscle and the synapse in the anterior horn

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16
Q

LMN Lesion:

Strength?

Muscle Tone?

Stretch Reflex?

Atrophy?

Other Signs?

A

LMN Lesion:

Strength: Decrease

Muscle Tone: Decrease

Stretch Reflex: Decrease

Atrophy: Severe

Other Signs:

Fasciculation (visible small twitch), Fibrillation (not visible small twitch)

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17
Q

UMN Lesion:

Strength?

Muscle Tone?

Stretch Reflex?

Atrophy?

Other Signs?

A

UMN Lesion:

Strength: Decrease

Muscle Tone: Increase

Stretch Reflex: Increase

Atrophy: Mild

Other Signs: Clonus, Pathological Reflex (Babinski)

18
Q

Pathological Sign of LMN Lesion

A

Flaccid Paralysis

Results from denervation of muscle

Lack of muscle tone, absence of movement (plegia), decreased reflex

19
Q

Pathological Sign of UMN Lesion

A

Spasticity (continuous contraction)

Hyperreflexia

Clasp-knife

Clonus

Abnormal Reflex Sign (Babinski)

20
Q

Abnormal Superficial Flexor Reflexes?

A

Abdominal Cutaneous Reflex

Cremasteric Reflex (males)

Bulbocavernous Reflex

Anal Wink

21
Q

Clinical: Unilateral Face, Arm, and Leg Weakness (no associated Somatosensory Defects–pure Motor)

Hemiparesis or Hemiplegia

Locations Ruled Out?

Locations Rules In?

Lesion Location WRT to Weakness?

Common Cause?

A

Locations Ruled Out:

Cortical - would need whole motor cortex

Muscle/Peripheral Nerve - would have to be a lot

Spinal Cord/Medulla - Face would be spared

Locations Rules In:

Corticospinal / corticobulbar fibers between cortex and medulla (internal capsule, basilar pons, cerebral peduncle)

Lesion Location WRT to Weakness:

Contralateral to weakness

Common Cause:

Blood supply to Internal Capsule (Middle Cerebral Artery, Anterior Choroidal Artery), or Pons (Basilar Artery)

Demyelination or tumor at bold locations

22
Q

Lesion at Medulla–above / below?

Side affected?

A

Contralateral = Above

Ipsilateral = Below

23
Q

Clinical: Unilateral Face, Arm, Leg Weakness (with associated somatorsensory, oculomotor, visual defects)

Hemiparesis or Hemiplegia

Locations Ruled Out?

Locations Rules In?

Lesion Location WRT to Weakness?

Common Cause?

A

Locations Ruled Out:

Below medulla

Locations Rules In:

Entire primary cortex

Lesion Location WRT to Weakness:

Contralateral to weakness

Common Cause:

Infarct / hemorrhagic stroke, tumor, trauma, herniation

24
Q

Unilateral Arm and Leg Weakness or Paralysis

Locations Ruled Out?

Locations Rules In?

Lesion Location WRT to Weakness?

Common Cause?

A

Locations Ruled Out:

Cortical spinal tract below motor cortex and above medulla (no face)

Muscle or peripheral nerve

Spinal cord below C5 (would have some arm sparing)

Locations Rules In:

Arm/Leg area of motor cortex

Cortical Spinal Cord below Medulla and Above C5

Lesion Location WRT to Weakness:

Contralateral if Cortical or Medulla (above decussation)

Ipsilateral if Below

Common Cause:

Infarcts, Multiple Sclerosis, Lateral Trauma / Cervical Spinal Cord Compression

Associated Features:

Cortical may be associated with aphasia

Medial medulla may also lose vibration on side of lesion, tongue contralateral

25
Q

Unilateral Face and Arm Weakness or Paralysis

Locations Ruled Out?

Locations Rules In?

Lesion Location WRT to Weakness?

Common Cause?

Associated Features?

A

Locations Ruled Out:

Muscle or Peripheral Nerve

Internal Capsule or Below

Locations Rules In:

Face and Arm areas of Motor Cortex

Lesion Location WRT to Weakness:

Contralateral

Common Cause:

Middle Cerebral artery superior division

Tumors, abcesses

Associated Features:

UMN and dysarthria

Broca’s Aphasia (if dominant hemisphere)

26
Q

Unilateral Arm Weakness or Paralysis

Locations Ruled Out?

Locations Rules In?

Lesion Location WRT to Weakness?

Common Cause?

Associated Features?

A

Locations Ruled Out:

Corticospinal tract

Locations Rules In:

Arm area of Motorcortex

Peripheral nerves supplying arms

Lesion Location WRT to Weakness:

Contralateral = motorcortex

Ipsilateral = nerves

Common Cause:

Motor Cortex = Infarct of MCA, tumor

Nerve = Compression Injury, Diabetes

Associated Features:

Motor Cortex = UMN signs

Nerve = LMN signs

27
Q

Unilateral Leg Weakness or Paralysis

Locations Ruled Out?

Locations Rules In?

Lesion Location WRT to Weakness?

Common Cause?

Associated Features?

A

Locations Ruled Out:

Corticospinal tract above thoracic cord (no arm)

Locations Rules In:

Motor Cortex leg area

Lateral corticospinal tract below T1

Peripheral Nerve supplying leg

Lesion Location WRT to Weakness:

Motor Cortex = Contralateral

Spinal Cord/Nerve = Ipsilateral

Common Cause:

Motor Cortex = Anterior Cerebral Artery, tumor

Spinal Cord = Unilateral cord trauma, tumor, MS

Nerve = Compression, Diabetes

Associated Features:

Motor Cortex = UMN signs

Spinal Cord = UMN signs, Brown-Sequard

Nerve = LMN signs

28
Q

Unilateral Face Weakness or Paralysis

Locations Ruled Out?

Locations Rules In?

Lesion Location WRT to Weakness?

Common Cause?

Associated Features?

A

Locations Ruled Out:

Below Rostral Medulla

Locations Rules In:

Common - CN VII

Uncommon - Lesion in face area, facial nucleus, pons, rostral medulla

Lesion Location WRT to Weakness:

Ipsilateral if CN VII/nucleus, Contra if motor cortex/internal capsule

Common Cause:

CN VII (Bell’s Palsy), Trauma, Surgery

Associated Features:

CN VII - Forehead and orbicularis oculi, hyperacusus, loss of taste, ear pain

Motor Cortex - Forehead spared, tongue weakness

29
Q

Bilateral Arm Weakness or Paralysis

Locations Ruled Out:

Locations Rules In:

Lesion Location WRT to Weakness:

Common Cause:

Associated Features:

A

Locations Ruled Out:

Corticospinal Tracts (no face, legs)

Locations Rules In:

Medial fibers of both lateral corticospinal tracts

Bilateral cervical spine ventral horn cells

Lesion Location WRT to Weakness:

Medial (bilateral)

Common Cause:

Central Cord Syndrome (Syringomyelia, cord tumor)

Anterior Cord Syndrom (ant. Art. infarct, trauma)

Peripheral Nerve (carpel tunnel, disc herniation)

Associated Features:

Central cord syndroms or anterior cord syndrome, peripheral nerve disorders affecting both arms

30
Q

Bilateral Leg Weakness or Paralysis

Locations Ruled Out:

Locations Rules In:

Lesion Location WRT to Weakness:

Common Cause:

Associated Features:

A

Locations Ruled Out:

Corticospinal tract above T1 (no face, arms)

Locations Rules In:

Motor Cortex (both leg areas)

Lateral Corticospinal Tracts below T1

Cauda Equina Syndrome

Lesion Location WRT to Weakness:

Medial (bilateral)

Common Cause:

Motor Cortex = Parasagittal Meningioma, Cerebral Palsy

Spinal Cord (Common) = Tumor, Trauma, Myelitis, Epidural abscess

Bilateral Peripheral nerve = Cauda Equina Sundrom, Guillian Barre, Lambert-Eaton, diabetes

Associated Features:

31
Q

Bilateral Arm and Leg Weakness or Paralysis

Locations Ruled Out:

Locations Rules In:

Lesion Location WRT to Weakness:

Common Cause:

Associated Features:

A

Locations Ruled Out:

Between motor cortex and medulla

Spinal cored below C5 (arms would be spared)

Locations Rules In:

Motor Cortex (bilateral arm and leg)

Corticospinal Tracts between medulla and C5 (bilateral lesions)

Peripheral Nerve and Muscle disorders of all four limps

Lesion Location WRT to Weakness:

Medial (bilateral)

Common Cause:

Motor Cortex = Watershed infarcts, anterior cerebral palsy

Upper Cervical / Lower Medulla = Tumor, Trauma, Infarct, MS

Nerve/Muscle = Lots

Associated Features:

Motor Cortex = UMN, cognitive dysfunction, aphasia

Upper Cervical Cord = UMN, sensory dysfunction, respiratory issues, trigeminal issues

Lower Medullary = UMN, headache, tongue weakness, hiccups, abnormal eye movements

Peripheral Nerve = LMN

32
Q

Generalized Weakness and Paralysis

Locations Ruled Out:

Locations Rules In:

Lesion Location WRT to Weakness:

Common Cause:

Associated Features:

A

Locations Ruled Out:

Small focal or unilateral lesions

Lower medulla or spinal cord (face would be spared)

Locations Rules In:

Motor cortex (bilateral)

Corticospinal tracts between corona radiata and pons (bilateral)

Lesion Location WRT to Weakness:

Common Cause:

Global cerebral anoxia, Pontine infarct (Locked In Syndrome), Advanced ALS, Guillain Barre, Myasynthia, Botulism

Associated Features:

Motor / Corticospinal = UMN

Nerve = LMN

33
Q

Clinical: Spinal Muscular Atrophy

A

Congenital degeneration of cells of Anterior Horns of Spinal Cord

Mutation of SMN1 Gene

Diffuse proximal muscle weakness (more in lower limbs)

Decrease deeo tendon reflex

34
Q

Clinical: Amyotrophic Lateral Sclerosis (ALS, Lou Gehrig’s Disease)

A

Heterogeneous group of neurodegenerative diseases of both UMN and LMN

Progressive loss of Anterior Horn Cells, Corticobulbar, Corticospinal tract, and Betz neurons in motor cortex and neurons of te cranial nerve motor nuclei

Small muscles will waste first, weight loss, speech, respiration difficult

35
Q

Clinical: Occlusion of Anterior Spinal Artery

A

Spares dorsal columns and Lissauer tract

Can be caused by Aortic Aneurysm Repair

UMN below lesion

LMN at level of lesion

Loss of temp/pain sensation below lesion

36
Q

Clinical: Tabes Dorsalis

A

Caused by Syphilis

Demyelination of dorsal columns and roots

Progressive sensory ataxia, impaired proprioception

Romberg Sign

37
Q

Clinical: Syringomyelia

A

Syrinx expans and damages the Anterior White Commissure of Spinothalamic Tract

Bilateral loss of pain and temperature in cape like pattern

38
Q

Clinical: Vitamin B12 Deficiency

A

Demyelination of Spinocerebellar tracts, Lateral corticospinal tracts, dorsal columns

Symptoms: Ataxic Gate, Paresthesia, Impaired position and vibration sense

39
Q

Clinical: Cauda Equina Syndrome

A

Compression of spinal roots L2 and below

Cause: Disc herniation

Absense knee/ankle reflex, loss of bladder and anal sphincter reflex

Saddle anesthesia

40
Q

Clinical: Poliomyelitis

A

Caused by Polio virus

Destruction of cells in Anterior Horn

LMN signs

41
Q

Clinical: Brown-Sequard (prob on exam..)

A

Hemisection of Spinal Cord

Ipsilateral loss of all sensation at level of lesion

Ipsilateral LMN sign at level of lesion

Ipsilateral UMN sign below level of lesion

Ipsilateral loss of pripriocepition, vibration, light tourch below lesion

Contralateral loss of pain, temp, and non-discrimative touch below lesion

42
Q
A

SF2 - Test 2 (17 decks)

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