Spinal meniges Flashcards
1
Q
Dura Mater
A
- 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
Q
External Filum Terminale
A
Extention of the dural sac that anchors the sac to the coccyx
3
Q
Dural/Thecal sac
A
Area encasing the entire CNS made of the dura mater
4
Q
Meningitis
A
Any infection causing inflammation of the meninges. Diagnosed with a lumbar puncture (to get CSF for diagnosis)
5
Q
Arachnoid mater
A
- Intermediate, more delicate layer
- follows the dura mater’s encasing
- forms trabeculae between the arachnoid and dura mater to connect the two
6
Q
Pia mater
A
- Most internal/delicate of meninges
- Associated with blood vessels, rootlets, dorsal/ventral roots, merging with the spinal nerves epineurium
7
Q
Denticulate ligament
A
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
Q
Internal filum terminale
A
extention of the pia mater that extends from the conus medullaris
9
Q
Epidural space
A
- External to the dural sac
- Has fat and extensive internal vertebral plexus
10
Q
Subdural space
A
B/t spinal dura and arachnoid mater, is more potential space
11
Q
Sunarachnoid space
A
- b/t the arachnoid and pia mater
- Filled with CSF
12
Q
Lumbar Cistern
A
Expanded portion fo the subarachnoid space that has high volumes of CSF ►great for spinal taps/injection of anesthetics
13
Q
Epidural Pros/Cons
A
- Larger dose needed
- Longer onset of analgesia
- can be at any spinal level
- used segmentally
14
Q
Spinal anaesthesia Pros/Cons
A
- Lower dosage
- Quicker onset
- only in lumbar region
- More generalized
15
Q
Main arteries of the spinal cord
A
Anterior spinal artery (1)
Posterior spinal artery (2)
16
Q
Segmental spinal arteries
A
- Branch from various sources and enter the intervertebral foramen
- give rise to anterior/posterior radicular/segmental medullary arteries
17
Q
Anterior & Posterior Radicular arteries
A
Course along anterior/posterior spinal roots/rootlets to supply structures (radicular=roots), but do not connect to spinal arteries
18
Q
Anterior & posterior radicular arteries
A
Periodically reinforce main spinal arteries (radicular arteries do not connect to spinal arteries)
19
Q
Greater anterior segmental medullary artery
A
- 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
Q
Dorsal/Ventral spinal veins
A
- 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
Q
Internal Vertebral plexus
A
- 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
Q
Recurrent meningeal branches
A
- 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
Q
Autonomic fibers
A
aid is regulating blood flow
24
Q
Portion of nerves that can lead to increased reflexive tone and referred pain from an intervertebral disc rupture or meningitis
A
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
27
Receptor types
Exteroceptive
Proprioceptive
28
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
