1.2 Spinal Cord and Autonomic Nervous System Flashcards

1
Q

In the adult the spinal cord ends as a tapered portion termed the … at the L1 vertebral level.

  • In newborns it ends at L3 vertebral level)
A

conus medullaris

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2
Q

Due to the discrepancy between the spinal cord and the vertebral column, the more caudal spinal nerves are longer and more vertical forming the…

A

cauda equina

“horse tail”

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3
Q

What are the 3 layers, meninges, surrounding the spinal cord?

A
  1. Dura mater
  2. Arachnoid mater
  3. Pia mater
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4
Q

What connection of pia mater, connects the conus medullaris to the coccyx?

A

filum terminale

tethering to keep the coccyx in place

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5
Q

In the CNS, what forms the gray matter?

A

neuronal cell bodies

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6
Q

In the CNS, what forms the white matter?

A

interconnecting nerve fiber tracts

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7
Q

In the CNS, what is a discrete group of neuronal cell bodies called?

A

Nucleus

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8
Q

In the PNS, what is a discrete group of neuronal cell bodies called?

A

Ganglion

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9
Q

What are spinal nerves responsible for?

A

Conveying information to/from the gray mater horns of the spinal cord

  • DO NOT supply internal structures (viscera within thoracic or abdominopelvic cavities)
  • DO NOT supply structers of the head
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10
Q

What is the Dorsal (posterior) horn of the CNS gray matter responsible for?

A

Receives Sensory Information

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11
Q

What is the Ventral (anterior) horn of the CNS gray matter responsible for?

A

Transmits Motor Information

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12
Q

What is the Lateral horn of the CNS gray matter responsible for?

A

Transmits Motor Information

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13
Q

Where do the 8 cervical paired spinal nerves recieve their name from?

A
  • C1 - C7 named for vertebra inferior to their exit
  • C8 exits between C7 and T1 vertebrae
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14
Q

Where do the 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal paired spinal nerves recieve their names from?

A

Named by vertebra superior to their point of exit

i.e. T2 exits between vertebrae T2 and T3

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15
Q

Fibers emerge from the spinal cord as what?

A

rootlets

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16
Q

What do rootlets converge to form?

A

2 Nerve Roots

  • Anterior (ventral) - motor fibers from the ventral horn of the spinal cord
  • Posterior (dorsal) - sensory fibers from the dorsal horn of the spinal cord
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17
Q

What do the anterior and posterior roots converge to form?

A

Mixed Spinal Nerve

  • Contains both motor and sensory fibers (mixed fibers)
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18
Q

Where does the formation of the mixed spinal nerve occur?

A

At or near the intervertebral foramen

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19
Q

What does the mixed spinal nerve immediately divide into?

A

Anterior and Posterior Rami

Each ramus carries both sensory and motor fibers

*rami = branch

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20
Q

What does the posterior (dorsal) rami supply and what fibers does it carry?

A
  • Deep (true) muscles of the back
    • Somatic Motor
  • Overlying skin
    • Somatic sensory
  • Vasculature (arteries) structures supplying these structures
    • Postganglionic Sympathetic Fibers
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21
Q

What does the anterior (ventral) rami supply?

A
  • Anterior and lateral trunk
  • Upper and lower limbs
    • Generally partcipating in plexus formation
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22
Q

What fibers does the anterior (ventral) rami carry?

A
  • Somatic motor
  • Somatic sensory
  • Postganglionic sympathetic fibers
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23
Q

Where are the cell bodies located in the sensory (afferent) subdivision of the PNS?

A

Outside, but close to the CNS

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24
Q

Where are the cell bodies located in the motor (efferent) subdivision of the PNS?

A

Gray matter of CNS

25
Q

How do the sensory (afferent) fibers enter the CNS?

A

Via the posterior (dorsal) root) of spinal or cranial nerves

26
Q

Where do the motor (efferent) fibers exit the CNS?

A

Anterior (ventral) roots of spinal or cranial nerves

27
Q

What does the somatic subdivision of the PNS do?

A

Conveys info to/from CNS, and body wall and extremities (skeletal muscle)

28
Q

What does the visceral subdivision of the PNS do?

A

Conveys info to/from CNS and, internal organs and blood vessels

29
Q

How many neurons are between the CNS and the end organ (target) in the Somatic Motor System?

A

1 neuron

30
Q

What is the target organ of the somatic motor system?

A

ALWAYS skeletal muscle

31
Q

How many neurons are between the CNS and the end organ (target) in the visceral motor system (ANS)?

A

2 neuron system

32
Q

Where is the cell body of the preganglionic neuron of the visceral motor system (ANS) located?

A

grey matter of CNS

33
Q

What are the target organs of the visceral motor system (ANS)?

A
  • Smooth muscle (non-striated, involuntary)
  • Glands
  • Modified cardiac muscle
  • SA and AV nodes
34
Q

Where do you find preganglionic sympathetic cell bodies?

A
  • Forms the intermediolateral cell column (IML)
  • Composes the lateral horn of the spinal cord from T1 - L2

IML is the only place preganglionic sympathetic cell bodies exist

35
Q

Where do preganglionic sympathetic fibers exit the CNS?

A

Anterior (ventral) roots

becoming components of the mixed spinal nerve and entering the anterior ramus

36
Q

Where do the preganglionic sympathetic fibers exit the spinal nerve?

A

White Ramus Communican

Communicating branch between spinal nerves T1 - L2 (same as IML) only and the sympathetic trunk

37
Q

What is the sympathetic trunk composed of?

A

paravertebral ganglia

38
Q

What is the course the preganglionic sympathetic fibers take if the target structures are located within the body wall of T1 - L2 OR within the thoracic cavity?

A

Synapses with a postganglionic cell body within a paravertebral ganglia of the sympathetic trunk at the SAME level it entered the sympathetic trunk.

39
Q

What is the course the preganglionic sympathetic fibers take if the target structures are located above T1?

A

the preganglionic sympathetic fibers will ascend within the sympathetic trunk to synapse with a postganglionic cell body located in a paravertebral ganglia in the cervical region.

40
Q

What is the course the preganglionic sympathetic fibers take if the target structures are located below L2?

A

Descend within the sympathetic trunk to synapse with a postganglionic cell body located in a paravertebral ganglia in the lower lumbar or sacral region.

41
Q

What is the course the preganglionic sympathetic fibers take if the target structures are located in the abdomen or pelvic cavities?

  • Only involves fibers involved in the sympathetic innervation of the abdominopelvic viscera (below the diaphragm)
A

They will pass through the sympathetic trunk WITHOUT synapsing.

  • Once the preganglionic sympathetic fibers leave the sympathetic trunk they are called thoracic or lumbar splanchnics.
42
Q

What is the branch of postganglionic fibers that arises from the paravertebral ganglia of the sympathetic trunk, traveling laterally, called that targets: smooth muscle and glands of body wall and limbs aka structures supplied by Spinal Nerves?

A

Gray ramus communicans

43
Q

What is the branch of postganglionic fibers that arises from the paravertebral ganglia of the sympathetic trunk called that targets: the head, since no spinal nerves go to the head?

A

Cephalic arterial rami

surround arteries going to the head forming a periarterial plexus to reach their targets

44
Q

What is the branch of postganglionic fibers that arises from the paravertebral ganglia of the sympathetic trunk, running medially, called that targets: innervate the viscera of the thoracic cavity?

A

Cardiopulmonary splanchnics

45
Q

What is the path of the thoracic splanchnic nerves?

A
  • Preganglionic sympathetic fibers arise from the thoracic region of the sympathetic trunk
  • They do NOT synapse with the sympathetic trunk
  • Pass into abdominal cavity near the aorta
  • Synapse within a prevertebral ganglia on a postganglionic cell body
  • postganglionic fibers travel on arteries to their targets
46
Q

What are the main differences between the thoracic splanchnics and the lumbar splanchnics?

A
  • Arise from lumbar portion of sympathetic trunk (L1 -L2)
  • Innervate pelvic viscera
47
Q

What are the 2 locations of preganglionic parasympathetic cell bodies?

A
  1. Cranial - gray matter of brainstem
  2. Sacral - gray matter of S2 - S4 spinal cord
48
Q

How do the preganglionic parasympathetic fibers exit?

A
  1. Cranial - as CNs III, VII, IX, X
  2. Sacral - via anterior roots of spinal nerves S2 - S4 as pelvic splanchnic nerves
49
Q

Where are the postganglionic parasympathetic cell bodies of the sacral division located?

A

Within the wall (tissue) of the target organ located in an intramural ganglia

50
Q

Where are the postganglionic parasympathetic cell bodies in the head located?

A

Any of the 4 pairs of parasympathetic ganglia that are located close to their target.

C.O.P.S.

51
Q

Describe the postganglionic parasympathetic fibers

A

They are very short and within the wall of an organ, since the postganglionic cell bodies are already in the target tissue.

52
Q

What do parasympathetics NOT innervate?

A

Structures of the body wall or limbs

ONLY INNERVATES:

  • specific structures in the head
  • thoracic, abdominal, and pelvic viscera
53
Q

What is the job of the somatic sensory system?

A

Input to CNS from skin or skm

54
Q

Where is the cell body located in the somatic sensory system?

A

Dorsal root (spinal) ganglion

55
Q

How does the somatic sensory system work?

A
  • 1 neuron system
  • The neuron has a distal (peripheral) process to the target, and a central process to the CNS
  • NO SYNAPSE occurs in a sensory ganglion
56
Q

What is the job of the visceral sensory system?

A

Carry information from viscera to CNS (pain, distension)

57
Q

How do the distal (peripheral) fibers in the visceral sensory system get to the sympathetic trunk?

A

Hitching a ride on splanchnic nerves (cardiopulmonary, thoracic, or lumbar)

58
Q

What is the path of the visceral sensory system once it arrives at the sympathetic trunk?

A

Exits the trunk via white ramus communican at the appropriate spinal cord level to travel back to their cell body, located in the dorsal (spinal) root ganglion.

59
Q
A