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Anatomy Unit 3 > Peripheral Nerves 1 (part 1) > Flashcards

Peripheral Nerves 1 (part 1) Flashcards

1
Q

Each packet of axons is called a ______. Formed by gathering several axons into a wad.

A

Fasciculus

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2
Q

A layer of connective tissue surrounding each fasciculus.

A

Perineurium

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3
Q

Larger connective tissue layer that surrounds several perineurium (Fasciculi).

A

Epineurium

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4
Q

When you see a nerve in lab, what you’re seeing is the ______.

A

Epineurium

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5
Q

A thin layer of connective tissue around each individual axon.

A

Endoneurium

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6
Q

Lipid material that is an excellent insulator.
Helps to save energy by making it so that you don’t have to repolarize the whole axon when you have an action potential. Also helps to increase velocity via skipping from node of ranvier to node of ranvier.

A

Myelin

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7
Q

Axons that carry sensory information from the viscera (organs) into the CNS.

A

General Visceral Afferent (GVA)

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8
Q

Fibers that carry sensory information from vision, hearing, and equilibrium to the CNS.

A

Special Somatic Afferent (SSA)

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9
Q

Fibers that carry sensory information from olfaction and taste to the CNS.

A

Special Visceral Afferent (SVA)

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10
Q

Fibers that carry sensory information from the general senses (touch, vibration, kinesthetic, and 2 point discrimination) to the CNS.

A

General Somatic Afferent (GSA)

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11
Q

Fibers that originate from the CNS and innervate the muscles of the face, head, neck, and pharynx/larynx.
-Ex: Platysma

A

Special Visceral Efferent (SVE)

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12
Q

Supplies motor fibers to everything else in your body. Biceps, Quadriceps, calf muscles, etc.

A

Somatic Efferent (SE)

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13
Q

Supplies motor fibers to the viscera. ANS parasympathetic/Sympathetics

A

General Visceral Efferent (GVE)

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14
Q

Large fibers that are heavily myelinated and have a very fast conduction.
-Can be sensory or motor
-Have sensory subunits: alpha, beta, & gamma
-Delta subunit is for fast pain

A

A fibers

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15
Q

Fibers that are medium sized and lightly myelinated (slower than A)
-Pre-ganglionic parasympathetics/sympathetics

A

B fibers

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16
Q

Fibers that are small and unmyelinated.
-No saltatory conduction
-Slowest conduction speed
-Post-ganglionic parasympathetics/sympathetics
-Carry slow pain fibers. Injury occurs, but you can’t pinpoint the exact location of the injury.

A

C fibers

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17
Q

Big fibers with lots of myelin and a very fast speed of conduction
-Largest diameter and fastest speed of conduction
-Required to coordinate the MSK system. Fibers project through the cerebellum and carry information anywhere we need to have balance and equilibrium.
-Ex: Allow us to sit up straight. If we didn’t have these, we’d fall over.

A

A Alpha Fibers

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18
Q

Fairly large and fast fibers with myelin.

A

A Beta Fibers

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19
Q

Somewhat large fibers with a fast, but not as fast as others speed of conduction.

A

A Gamma Fibers

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20
Q

What type of cells create myelin in the PNS?

A

Schwann Cells

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21
Q

A bare spot that is not occupied by myelin that allows the depolarization to skip from one node to another very quickly (Saltatory Conduction)

A

Nodes of Ranvier

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22
Q

Depolarization skips from one node to another very quickly (Like skipping rocks in a pond). This greatly enhances the speed of conduction because you only have to depolarize each node of ranvier, not the whole axon.

A

Saltatory Conduction

23
Q

Occurs when axons have lost their myelin and need extra energy to depolarize. Have lost their ability to skip from node to node, so they have slower Action Potentials.

A

Demyelinating Disease (Multiple Sclerosis)

24
Q

Fibers that are primarily for fast pain. Allow you to localize the pain.
-Ex: Walking on the beach and cut your foot, can tell exactly where the pain is coming from

A

A Delta Fibers

25
Q

Fibers that carry motor impulses to innervate a group of skeletal muscles called the Extrafusal Fibers
-Bulk of skeletal muscle
-When these contract, makes a joint move (Flex, extend, rotate, etc).

A

A Alpha Fibers (motor fibers)

26
Q

Fibers that carry motor impulses to the extrafusal and intrafusal fibers.
-Somatic Efferent (SE) Fibers

A

A Beta Fibers (motor fibers)

27
Q

Fibers that carry motor impulses to the Intrafusal muscle fibers.
-Somatic Efferent (SE) fibers

A

A Gamma Fibers (motor fibers)

28
Q

The striations that you can see on skeletal muscle. Innervated by A Alpha (and partly by A Beta) Fibers.
-Forms the bulk of skeletal muscle
-When these contract, makes a joint move (Flex, extend, rotate, etc).

A

Extrafusal Fibers

29
Q

A fusiform shape attached to an extrafusal fiber.
-Small, but tells the extrafusal fibers what to do (relax, contract, etc).
-Multiple of these to one extrafusal fiber.
-Innervated by A Gamma (and partly by A Beta) fibers.

A

Intrafusal fibers

30
Q

Sensory fibers coming from the Intrafusal Muscle fibers and project back to the CNS.
-Measure the rate of intrafusal fiber length change. Intrafusal fibers are dynamic - changing all the time depending on demand.
-These measure and are aware of those changes and tell the CNS what condition the muscle fiber is in.
-GSA Fibers

A

A Alpha Fibers (Sensory) Type 1a

31
Q

Sensory fibers that originate from the Golgi Tendon Organ (GTO).
-Reacts to tension
-When a muscle contracts, it places tension on the tendon as it pulls, causing the joint to change its shape.
-Tension on the GTO gives feedback on the muscle, causing it to relax
-Inhibits muscle contraction; returns it to starting position

A

A Alpha Fibers (Sensory) Type 1b

32
Q

Sensory fibers that originate from the Intrafusal muscle fibers and measure their static length.
-Measure the length of the intrafusal fibers at any given time and activity.

Also, carry general sensory information r/t fine tactile senses from the PNS to the CNS (Discriminative touch, proprioception/kinesthesia, vibration, stereognosis, and 2 point discrimination)
-GSA Fibers

A

A Beta Fibers (Sensory) Type II

33
Q

Ability to know the position of the body’s limbs

A

Proprioception/kinesthesia

34
Q

The ability to detect a vibrating object

35
Q

The ability to pick up an object and be able to tell its shape without looking at it.

A

Stereognosis

36
Q

The ability to tell that there are 2 different points touching you that are close together

A

2-point Discrimination

37
Q

Fast pain fibers.
-Carry Epicritic Pain
-Sharp, localized, and lancinating (cutting) pain
-Acute injury (ex: Stepped on a nail)
-GSA Fibers

A

A Delta Fibers (Sensory) Type III

38
Q

Pain that you can localize (tell exactly where it comes from)

A

Epicritic Pain

39
Q

Fibers that carry ANS Pre-ganglionic Para/Sympathetic Motor Fibers.
-Start at a nucleus that projects axons out of the CNS and ends at an autonomic ganglion where they synapse with post-ganglionics.
-GVE Fibers

A

B Fibers (motor)

40
Q

Also called White Rami Communicantes

A

Pre-ganglionic Sympathetic fibers

41
Q

Fibers that receive information from glands or heart and send it back into the CNS
-GVA Fibers
-Visceral Afferent Pain

A

B Fibers (Sensory)

42
Q

Fibers that carry post-ganglionic Para/Sympathetic Motor fibers.
-GVE fibers

A

C Fibers (Motor)

43
Q

Also called Gray Rami Communicantes

A

Post-ganglionic Sympathetic Fibers

44
Q

Fibers that carry slow pain fibers.
-Carry protopathic pain
-Dull, aching, burning pain
-Poorly localized
-Fibers are unmyelinated
-GSA Fibers

A

C Fibers (Sensory) Type IV

45
Q

Pain that you are unable to localize.
-Ex: Rheumatoid Arthritis, cancer, etc.
-Carried by C Fibers (Sensory) Type IV

A

Protopathic Pain

46
Q

Injury occurs - break in the endoneurium
-Axon itself is severed
-Retrograde degeneration to the 1st node of ranvier (towards the cell body)
-Cell body is fine for right now

A

Immediate Injury

47
Q

Anterograde degeneration - from the site of injury and distal

A

Wallerian Degeneration

48
Q

Degeneration from the site of injury back towards the Cell Body

A

Retrograde Degeneration

49
Q

-Cell body (neuron) becomes swollen, nucleus is no longer centered due to Na/K pump inhibition and Na accumulation inside the cell (water follows - edema)
-Myelin droplets scattered at the site of injury
-Schwann Cell proliferation
-Retrograde degeneration to the first node of ranvier
-Phagocytes present to remove debris

A

48 hours post injury

50
Q

-Swollen cell body (neuron) and misplaced nucleus
-Neuronal tube is beginning to scar over at the site of injury. Re-establishing the neural tube to conduct the axon
-Proliferating Schwann cells
-Debris removed by macrophages
-Axonal Sprouting occurs as neuron attempts to regenerate

A

96 hours post injury

51
Q

-Endoneurial tube has heavy scarring
-Lots of Schwann Cells present
-Axonal sprouts occurring with some degenerating, but some successfully re-establishing connecting in the neural tube

A

120 hours post injury

52
Q

Regeneration is very slow, about 2.5 mm/24 hrs.
-The shorter the distance, the better prognosis of regeneration

A

Regeneration

53
Q

Cells that make myelin in the CNS
-Cannot regenerate if the axons are severed

A

Oligodendrocytes

Anatomy Unit 3 (9 decks)

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