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SF2 2 > Descending Spinal Cord > Flashcards

Descending Spinal Cord Flashcards

1
Q

Upper Motor Neurons

A

Motor neurons projecting from cortex to the spinal cord or brain stem

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2
Q

Lower Motor Neurons

A

Project from the CNS via the Anterior Spinal Roots or via cranial nerve to various muscle cells

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3
Q

Most clinically important descending motor pathway

A

Lateral Corticospinal Tract

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4
Q

Controls voluntary movement of extremities (pathway)

A

Corticospinal Tract

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5
Q

Most of the primary neurons that contribute to the corticospinal tract are found in…

A

Cortical layer 5

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6
Q

> 50% of corticospinal fibers originate from primary motor cortex. Where is this in the cerebral cortex?

A

Brodmann 4

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7
Q

Location of supplementary motor and premotor cortex

A

Brodmann 6

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8
Q

Corticobulbar tract

A

Fibers from cortex to brain stem (motor fibers for face)

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9
Q

Site of origin of corticospinal tract

A

Primary motor cortex and other front and parietal areas

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10
Q

Site of decussation of corticospinal tract

A

Pyramidal decussation at the cervicomedullary junction

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11
Q

Corticospinal tract path to medullary pyramids

A

cerebral cortex -> corona radiata -> internal capsule -> midbrain cerebral peduncles (specifically basis pedunculi) -> ventral pons (basis pontis) -> form medullary pyramids

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12
Q

Transition between medulla and spinal cord

A

Cerivcomedullary junction (found at the foramen magnum)

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13
Q

Formation of the anterior corticospinal tract

A

85% of corticospinal fibers decussate ay pyramidal decussation to continue on as lateral corticospinal tract. However, the remaining fibers stay ipsilateral and form the anterior corticospinal tract

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14
Q

Indirect Corticospinal Pathways

A

Consists of a number of small pathways that primarily regulate the background tone and activity in muscle without which a normal movement could not be made.

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15
Q

Tracts of Extrapyrimidal Pathways

A

1) Rubrospinal
2) Tectospinal
3) Reticulospinal
4) Vestibulospinal

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16
Q

Function of Extrapyrimidal Pathways

A

Motor modulation and reflex/postural movement

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17
Q

Origin of Rubrospinal Tract

A

Red nucleus (Brain stem)

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18
Q

Point of decussation of Rubrospinal Tract

A

Ventral Tegmentum (midbrain)

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19
Q

Descending path of the Rubrospinal Tract

A

Travels down the lateral column and is only found in the upper cervical segments (for the hands yeah)

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20
Q

Function of the Rubrospinal Tract

A

Coordinates fine muscle movement, automatic movements of locomotion and posture

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21
Q

Function of the Vestibulospinal Tract (both lat/med)

A

Controls movement of head in response to auditory and visual stimuli

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22
Q

Origin of the Vestibulospinal Tract (both lat/med)

A

Lateral Vestibulospinal Tract: Lateral Vestibular Nucleus (lower Pons)

Medial Vestibulospinal Tract: Medial Vestibular Nucleus (rostral medulla)

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23
Q

Function of Reticulospinal Tract (both subtypes)

A

Controls movement and muscle tone

24
Q

Origins of two subtypes in Reticulospinal Tract

A

Medial Pontine Reticulospinal Tract: Medial Pontine Reticular Formation

Lateral Reticulospinal Tract: Medullary Reticular Formation

25
Q

Origin of Tectospinal Tract

A

Superior colliculi (midbrain)

26
Q

Decussation of Tectospinal Tract

A

Dorsal Tegmentum (midbrain)

27
Q

Structure Tectospinal Tract descends in

A

Anterior funiculi

28
Q

Function of Tectospinal Tract

A

Head and arm movement in response to visual and other stimuli

29
Q

Alpha Motor Neurons

A

Supply the extrafusal fibers of skeletal muscles.

30
Q

Gamma Motor Neurons

A

Supply the intrafusal fibers of neuromuscular spindles. Regulate sensitivity of muscle

31
Q

Renshaw Cells

A

Interneurons in the spinal cord which act on motor neurons

32
Q

Most important function of Renshaw Cells

A

Permits co-contraction of prime movers and their antagonists in order to fix one or more joints

33
Q

Motor neurons supplying axial (vertebral) and proximal limb muscles are recruited mainly indirectly by the Lateral Corticospinal Tract by way of _____ ______ in the intermediate gray matter and the base of the anterior horn.

A

excitatory interneurons (aka internuncials)

34
Q

First neurons to be activated by the Lateral Corticospinal Tract during voluntary movements. Cause the antagonist muscles to relax before the prime movers contract. Also renders the antagonists’ motor neurons refractory to stimulation by spindle afferents passively stretched by the movement

A

Ia inhibitory interneurons (aka internuncials)

35
Q

Upper Motor Neuron Lesion

A

A lesion anywhere in the pathway prior to the synapse in the anterior horn

36
Q

Lower Motor Neuron Lesion

A

A lesion anywhere between the muscle and the synapse in the anterior horn

37
Q

Differences between UMN/LMN lesions (muscle tone and stretch reflexes)

A

Muscle tone decreases in LMN lesions but increases in UMN lesions. Stretch reflexes also decrease in LMN lesions but increase in UMN lesions.

38
Q

Flaccid Paralysis

A

Complete lack of muscle tone, total absence of voluntary movement (plegia) and decreased or absent muscle stretch reflex.

Results from denervation of muscle (LMN)

39
Q

List out UMN Pathological Reflexes

A

1) spasticity
2) hyperreflexia
3) clasp-knife reflex
4) clonus
5) abnormal superficial flexor reflexes

40
Q

Spasticity

A

Jerky movements; hypertonicity and hyperreflexia. Increases resistance to passive movement or manipulation.

41
Q

Cause of hyperreflexia

A

Due to loss of supraspinal inhibition of LMNs. Characteristic of UMN damage

42
Q

Clonus

A

Rhythmic, repetitive alternating contractions and relaxations of an agonist muscle (flexor) and its antagonist (extensor). Occurs in response to sudden an forceful passive movement, which stretches muscles.

43
Q

Common areas for clonus

A

Wrist and ankle

44
Q

Abdominal Cutaneous Reflexes

A

Scrape each side above (T8-T10) and below (T10-T12) umbilicus, observe abdominal muscle contraction

45
Q

Cremasteric Reflex (L1-L2)

A

Scrape upper inner thigh, observe ascent of testicles

46
Q

Bulbocavernous Reflex (S2-S4)

A

Contraction of renal sphincter in response to pressure on bulbocavernous muscle. Males compress glans penis, females (if foley catheter present traction will cause contraction)

47
Q

Anal Wink (S2-S4)

A

Contraction of anal sphincter in response to sharp stimulus in peri anal area

48
Q

Spinal Muscular Atrophy

A

Congenital degeneration of cells of anterior horns of spinal cord. Genetic disorder, mutation in SMN1 gene. LMN lesion with symmetric weakness (diffuse proximal muscle weakness and decreased deep tendon reflex)

Prenatal (SMA 0)
Infantile (SMA 1) also known as Werdnig Hoffman Disease

49
Q

Amyotrophic Lateral Sclerosis (ALS) also known as Lou Gehrig’s Disease

A

Heterogeneous group of neurodegenerative diseases in which both UMNs and LMNs degenerate. Age of onset between 52-55 yo. More common in men.

  • Progressive loss of anterior horn cells, corticobulbar/corticospinal tract, Betz (very large) neurons in motor cortex and cranial nerve nuclei
  • Patient presents with combination of UMN/LMN symptoms
  • Insidious onset, first sign/symptom is weakness in one area. Weight loss. Etc… i dont know look at the fucking slide jesus
50
Q

Inheritance pattern of Familial ALS (FALS)

A

Autosomal dominant

51
Q

Occlusion of Anterior Spinal Artery (effects of)

A
  • Spares dorsal columns and Lissauer Tract
  • UMN deficit below lesion (corticospinal tract)
  • LMN deficit at level of lesion (anterior horn)
  • Loss of temperature and pain sensation below lesion (spinothalamic tract)
52
Q

Tabes Dorsalis

A

Demyelination of dorsal columns and roots, caused by tertiary syphillis. Progressive sensory ataxia, impaired proprioception, poor coordination.

Produces Romberg sign

53
Q

Syringomyelia

A

Syrinx (fluid-filled cavity in brainstem/spinal cord) expands and damaged the anterior white commissure of spinothalamic tract. Bilateral loss of pain and temperature in cape like pattern

54
Q

Vitamin B12 Deficiency (in context of spinal cord)

A

Subacute combined degeneration. Demyelination of: spinocerebellar tracts, lateral corticospinal tracts, and dorsal columns.

Ataxic gait, paresthesia, and impaired position/vibration sense

55
Q

Cauda Equina Syndrome

A

Compression of Spinal Roots L2 and below. Often due to disc herniation.

Unilateral radicular pain, absent knee/ankle reflex, loss of bladder/anal sphincter reflex control, and saddle anesthesia.

56
Q

Poliomyelitis

A

Caused by poliovirus. Causes destruction of cells in anterior horn. LMN signs [asymmetric weakness, hypotonia, flaccid paralysis, fasciculations, etc]

57
Q

Brown-Sequard (Syndrome)

A

Hemisection of spinal cord.

Ipsilateral: Loss of all sensation at level of lesion. LMN signs at level of lesion. UMN signs below level of lesion (corticospinal tract damage). Loss of proprioception, vibration, light touch sense below level of lesion (dorsal column damage).

Contralateral: Loss of pain, temperature and non-discriminative touch below lesion (spinothalamic tract damage).

SF2 2 (14 decks)

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