1.2 Spinal Cord and Autonomic Nervous System Flashcards Preview

Gross Anatomy > 1.2 Spinal Cord and Autonomic Nervous System > Flashcards

Flashcards in 1.2 Spinal Cord and Autonomic Nervous System Deck (59)
1

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)

conus medullaris

2

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

cauda equina

"horse tail"

3

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

  1. Dura mater
  2. Arachnoid mater
  3. Pia mater

4

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

filum terminale

tethering to keep the coccyx in place

5

In the CNS, what forms the gray matter?

neuronal cell bodies

6

In the CNS, what forms the white matter?

interconnecting nerve fiber tracts 

7

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

Nucleus

8

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

Ganglion

9

What are spinal nerves responsible for?

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

10

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

Receives Sensory Information

11

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

Transmits Motor Information

12

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

Transmits Motor Information

13

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

 

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

 

14

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

Named by vertebra superior to their point of exit 

i.e. T2 exits between vertebrae T2 and T3

15

Fibers emerge from the spinal cord as what?

rootlets

16

What do rootlets converge to form?

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

17

What do the anterior and posterior roots converge to form?

Mixed Spinal Nerve

  • Contains both motor and sensory fibers (mixed fibers)

18

Where does the formation of the mixed spinal nerve occur?

At or near the intervertebral foramen

19

What does the mixed spinal nerve immediately divide into?

Anterior and Posterior Rami

Each ramus carries both sensory and motor fibers

*rami = branch

20

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

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

21

What does the anterior (ventral) rami supply? 

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

22

What fibers does the anterior (ventral) rami carry?

  • Somatic motor
  • Somatic sensory
  • Postganglionic sympathetic fibers

23

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

Outside, but close to the CNS

24

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

Gray matter of CNS

25

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

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

26

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

Anterior (ventral) roots of spinal or cranial nerves

27

What does the somatic subdivision of the PNS do? 

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

28

What does the visceral subdivision of the PNS do? 

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

29

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

1 neuron

30

What is the target organ of the somatic motor system?

ALWAYS skeletal muscle

31

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

2 neuron system

32

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

grey matter of CNS

33

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

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

34

Where do you find preganglionic sympathetic cell bodies?

  • 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

Where do preganglionic sympathetic fibers exit the CNS?

Anterior (ventral) roots 

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

36

Where do the preganglionic sympathetic fibers exit the spinal nerve?

White Ramus Communican

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

37

What is the sympathetic trunk composed of?

paravertebral ganglia

38

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?

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

39

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

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

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

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

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) 

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

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?  

Gray ramus communicans

43

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?

Cephalic arterial rami

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

44

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

Cardiopulmonary splanchnics

45

What is the path of the thoracic splanchnic nerves?

  • 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

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

  • Arise from lumbar portion of sympathetic trunk (L1 -L2
  • Innervate pelvic viscera 

47

What are the 2 locations of preganglionic parasympathetic cell bodies?

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

48

How do the preganglionic parasympathetic fibers exit?

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

49

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

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

50

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

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

C.O.P.S.

51

Describe the postganglionic parasympathetic fibers

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

52

What do parasympathetics NOT innervate?

Structures of the body wall or limbs 

ONLY INNERVATES:

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

53

What is the job of the somatic sensory system?

Input to CNS from skin or skm

54

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

Dorsal root (spinal) ganglion

55

How does the somatic sensory system work?

  • 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

What is the job of the visceral sensory system?

Carry information from viscera to CNS (pain, distension)

57

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

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

58

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

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