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Anatomy > Spinal Cord > Flashcards

Spinal Cord Flashcards

1
Q

What kind of fibers and what type of sensation carry the medial division of the dorsal root entering to the dorsal horn of the spinal cord?

A
  • Ia (muscle spindle or muscle stretch receptor) Ib fibers (Golgi tendinosus organ) ▶️ propioception (participation in reflex)
  • II, A-beta ▶️ touch
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2
Q

What pathways may produce a muscle contraction using the upper and lower motoneuron?

A
  • voluntarily contraction: UMN ▶️ LMN ▶️ skeletal muscle
  • reflex: fiber IA (muscle sensory neuron [afferent] from muscle spindle) ▶️ LMN ▶️ skeletal muscle
  • UMN control over reflexes - inhibitory effect
  • both alpha and gamma motoneurons (LMN) participate in reflexes
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3
Q

Functions of the muscle spindle (intrafusal muscle fibers)

A
  • sensory receptor in skeletal muscle stretch reflexes

- monitor the length and the rate of change in length of extrafusal fibers ▶️ connected in parallel with it

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4
Q

Function of the Golgi tendon organs, what type of fibers are the afferents that innervates them?

A
  • inverse muscle stretch reflex: monitor muscle tension

- Ib fibers

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5
Q

Role of gamma motoneurons in tension and reflexes

A
  • if they are (+) ▶️ contraction of intrafusal muscle fibers to contract at muscle spindle ▶️ (+) Alfa motoneuron ▶️ ⬆️ muscular tone
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6
Q

In case of UMN lesion, when do you get a decorticate or decerebrate rigidity? Why does it occur?

A
  • decorticate rigidity (flexion arm, extension leg) ▶️ lesion above midbrain
  • decerebrate rigidity (extension arm and leg) ▶️ lesion below midbrain
  • no inhibition on muscle stretch reflexes by UMN on LMN
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7
Q

What is the Babinski sign and for what is useful? Why does it occur?

A
  • extension of the great toe and fanning of other toes (reversal of cutaneous reflex) with cutaneous stimulus (stroking lateral surface of foot - normally flexor response)
  • corticospinal lesion - UMN lesion
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8
Q

What axons of the 3 neurons participating in sensory system pathways at the spinal cord or brain stem crosses the midline?

A
  • axons of the second-order neuron in CNS
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9
Q

Where is the second neuron in the dorsal column-medial lemniscal system?

A

Medulla (lower part) - nucleus gracilis and cuneatus

*fibers from these nuclei crosses the midline - ascend as medial lemniscus

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10
Q

Mention 3 signs to evaluate lesions at dorsal columns

A
  • astereognosis
  • vibratory sense: tuning fork, loss.
  • Romberg sign: positive
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11
Q

How is the presentation when a lesion occur in anterolateral (spinothalmic tract) system? What signs or symptoms can you find?

A
  • contralateral and 1 or 2 segments below the lesion, everything below that level
  • “anesthesia”: loss pain and temperature
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12
Q

What disease could cause a lesion in spinocerebellar tracts?

A
  • friedreich ataxia ▶️ degeneration of spinocerebellar pathways
  • ataxia of gait most common initial symptom
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13
Q

When do you have spastic bladder and how do you identify it?

A

Lesion of spinal cord above sacral spinal cord levels

  • urge incontinence
  • loss inhibition parasympathetic fibers ▶️ detrusor muscle respond to minimum amount of stretch during filling stage
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14
Q

When do you have atonic bladder and how do you identify it?

A

Lesion to the sacral spinal cord segments

  • continuous dribble of urine
  • loss parasympathetic innervation ▶️ loss contraction of detrusor ▶️ full bladder
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15
Q

What type of spinal cord lesion results as a late-stage of syphilis? Symptoms.

A
  • tabes dorsalis (dorsal column, and dorsal roots degeneration)
  • paresthesias, pain, polyuria (incontinence), Romberg sign, “high-step stride”, argyll Robertson pupils, ⬇️ reflex, ataxia, astereognosis, impaired vibration
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16
Q

Clinical presentation of amyotrophic lateral sclerosis

A
  • Progressive spinal muscular atrophy (ventral horn)
  • Bilateral flaccid paralysis in upper limbs - Common in cervical enlargement (often begins here) ▶️ progress up or down
  • Bilateral spastic weakness of the lower limbs - Primary lateral sclerosis (corticospinal tract)
  • Increased tone and reflexes
17
Q

Clinical presentation of occlusion of the anterior spinal artery

A
  • Loss bilateral temperature and pain below the level of lesion
  • Bilateral spastic paresis below the level of lesion
  • Spastic bladder
  • common at thoracic levels
18
Q

Clinical presentation of subacute combined degeneration

A
  • Bilateral spastic paresis below the lesion site
  • Bilateral alteration of touch, vibration, pressure sensation below the lesion site (other signs of dorsal column involvement may be present)
  • upper thoracic and lower cervical cord common
19
Q

Clinical presentation of syringomielia

A

Progressive

  • Early: bilateral loss of pain and temperature sensation in the hands and forearms
  • Then: bilateral flaccid paralysis of upper limbs
  • Late: Horner syndrome
  • usually at cervical level

Anatomy (22 decks)

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