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Flashcards in Spinal meniges Deck (60):
1

Dura Mater

  • Most exterior and densest
  • forms a sac that closes at S2 vertebrae
  • Is continuous with the cranial dura mater
  • Extends out to the spinal nerves
  • Attaches to the bondy framework

2

External Filum Terminale

Extention of the dural sac that anchors the sac to the coccyx

3

Dural/Thecal sac

Area encasing the entire CNS made of the dura mater

4

Meningitis

Any infection causing inflammation of the meninges. Diagnosed with a lumbar puncture (to get CSF for diagnosis)

5

Arachnoid mater

  • Intermediate, more delicate layer
  • follows the dura mater's encasing
  • forms trabeculae between the arachnoid and dura mater to connect the two

6

Pia mater

  • Most internal/delicate of meninges
  • Associated with blood vessels, rootlets, dorsal/ventral roots, merging with the spinal nerves epineurium

7

Denticulate ligament

Tissue found b/t dorsal/ventral rootlets that pierce into the arachoind mater in ~21 locations per side to stabilize the center od the dural sac

8

Internal filum terminale

extention of the pia mater that extends from the conus medullaris

9

Epidural space

  • External to the dural sac
  • Has fat and extensive internal vertebral plexus

10

Subdural space

B/t spinal dura and arachnoid mater, is more potential space

11

 Sunarachnoid space

  • b/t the arachnoid and pia mater
  • Filled with CSF

12

Lumbar Cistern

Expanded portion fo the subarachnoid space that has high volumes of CSF ►great for spinal taps/injection of anesthetics

13

Epidural Pros/Cons

  • Larger dose needed
  • Longer onset of analgesia
  • can be at any spinal level
  • used segmentally

14

Spinal anaesthesia Pros/Cons

  • Lower dosage
  • Quicker onset
  • only in lumbar region
  • More generalized

15

Main arteries of the spinal cord

Anterior spinal artery (1)

Posterior spinal artery (2)

16

Segmental spinal arteries

  • Branch from various sources and enter the intervertebral foramen
  • give rise to anterior/posterior radicular/segmental medullary arteries

17

Anterior & Posterior Radicular arteries

Course along anterior/posterior spinal roots/rootlets to supply structures (radicular=roots), but do not connect to spinal arteries

18

Anterior & posterior radicular arteries

Periodically reinforce main spinal arteries (radicular arteries do not connect to spinal arteries)

19

Greater anterior segmental medullary artery

  • aka Artery of Adamkiewicz
  • Significantly larger (and thus more important) segmental medullary artery typically found on the left side from one of the lower intercostal arteries

20

Dorsal/Ventral spinal veins

  • Drain directly into the internal vertebral plexus in subdural space
  • vary in number (generally 3-5 anterior & posterior, one at each sulcus/fissure)
  • on surface of spinal cord (pia mater)

21

Internal Vertebral plexus

  • Valveless system of venous channels in the epidural space
  • Connects with cranial dural sinuses, external vertebral plexus, and major veins in thorax, abdomen, & pelvis
  • allows for the spread of infection and neoplastic cells

22

Recurrent meningeal branches

  • Aka sinuvertebral nerves/recurrent nerves of Luschka/meningeal branch of spinal nerve
  • Sensory for periosteum of vertebrae, posterior longitudinal ligament, outer portion of annulus fibrosus, and meningies
  • Autonomic/sensory/sympathetic fibers

23

Autonomic fibers

aid is regulating blood flow

24

Portion of nerves that can lead to increased reflexive tone and referred pain from an intervertebral disc rupture or meningitis 

Recurrent meningeal branches

25

Spinal reflex

Fast, automatic, hard-wired muscular reaction to a stimulus. Only reacts with the spinal cord initially (so does not incorporate voluntary brain activity)

26

Components of a reflex arc

  1. Receptors
  2. Sensory neurons
  3. synpasing
  4. Motor neurons
  5. Effectors

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Receptor types

Exteroceptive

Proprioceptive

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Exteroceptive receptors

  • External environmental changes
  • Organs like skin, eyes, vestibular apparatus (acceleration of head/pull of gravity)

29

Proprioceptive Receptors

  • Changes in skeletal position (movement control)
  • Body postion and movement

30

Muscle Spindles

  • Capsules found scattered throughout skeletal muscles
  • Aligned parallel to fibers
  • Length/velocity sensitive
  • provides tonic signal
  • contains intrafusal muscles fibers
  • Gamma motor neurons

31

Ia and II sensory fibers

Used by muscle spindles to provide a tonic signal

32

Gamma motor neurons

  • Stimulate intrafusal muscle fibers
  • Functions: sensor reset and muscle tone

33

Golgi Tendon Organ

  • Proprioceptor that is sensitive to strain/stress on a muscle
  • Embedded in series with muscle fibers in the muscle/tendon junctions
  • provides phasic signals
  • leads to inhibition of stimulation of the same muscle it is found in

34

Ib sensory fibers

Used in Golgi Tendon Organs to send phasic signals

35

Afferent neurons

  • Pseudounipolar (t-shaped) neuron w/ cell body in the dorsal root ganglion
  • divided into periphral and central portions

36

Peripheral axon Process

Stimulated by the receptor (lateral and exteral to the dorsal root ganglion

37

Monosynaptic Reflex

a sensory neuron synapsing with a single motor neuron

38

Di-/polysynaptic reflex 

Interneurons used to connect multiple sensory neurons to motor neurons

39

Interneurons

  • Usually multipolar neuron whose cell body/dendrites are in dorsal gray horn and shor axon terminates on efferent neuron
  • Typically have an inhibitory effect (can be excitatory)

40

Efferent motor neuron

Multipolar neurons: cell bodies/dendrites in gray matter, axons pass out the ventral rootlets to rami to an effector (somatic or visceral)

41

Somatic Motor Neurons

  • Lower motor neurons stimulated by upper motor neurons (for voluntary) and stimulated by GSA/interneurons for reflexes

42

Alpha motor neurons

General somatic Efferent/Lower motor neurons that stimulate skeletal muscles

43

Motor unit

  • Alpha motor neuron + All muscle fibers it innervates
  • Varies from 5 to 2000 muscle fibers
  • Contains either slow or fast twitch fibers

44

Gamma motor neurons

GSE neurons that stimulate muscle spindle fibers

45

Visceral motor neurons

  • Cell bodies of GVE neurons found in lateral gray horn (T1-L2)

46

Preganglionic neurons

GVE neurons that originate inside the spinal cord, coursing out of the ventral root thru the white ramus communicans to a sympathetic trunk ganglion

47

Postganglionic neuron

  • Stimulated by GVE neurons
  • Act as efferent neuron to stimulate an effector, typically smooth muscle or gland

48

Effector for GSE/GVE

  • GSE: Skeletal muscle/Intrausal muscle spindle fibers
  • GVE: smooth muscle, cardiac muscle, arrector pili muscle, or glands

49

Somatosomatic reflex

GSA stimulates a motor output to GSE (finger prick to pulling hand away)

50

Somatovisceral Reflex

GSA to GVE (foot smashed to increased HR)

51

Viscerosomatic Reflex

GVA to GSE (ischemic heart muscle to referred pain/increased tone of paraspinal muscles)

52

Viscerovisercal reflex

GVA to GVE (noxious material in gut to increased gut motility)

53

Mytatic/Stretch Reflex

  • Stretching of tendon leads to muscle stretching
  • Muscle spindles stimulate Ia afferent neurons
  • Signal sent to alpha motor neurons within ventral gray horn
  • Alpha motor neurons terminate at the neurmuscular junction
  • Extrafusal muscle fibers stimulated leading to muscle contraction

54

Reciprocal inhibition

Ia stimulates Ia-interneuron that inhibits the alpha motor neuron of antagonistic muscle (causes muscle relaxation)

55

Gamma loop purpose

  1. Drives muscle tone
  2. Resets muscle spindle to new, shorter length

56

What do Gamma motor neurons innervate?

Muscle spindles, causing intrafusal muscle fibers to contract

57

Outcomes of intrafusal muscle fibers contracting

  1. Resetting the muscle tone (to pick up new stretch within skeletal muscle
  2. Regulate muscle tone via increasing Hz os signal on Ia sensory neuron (more alpha motor neurons stimulated)

58

Hypertonicity

Loss of inhibitory signal from brain causing rigidity

59

Spastic paralysis

Paralysis but reflexes work due to upper motor neuron disfunction

60

Flaccid paralysis

Lower neuron motor damage that results in no signal relayed to muscle