Spinal nerves with pathways

Question 1

Where does the spinal cord begin and end?

Answer 1

Begins at foramen magnum, ends at L1 or L2

Question 2

Where is the conus medularis located?

Answer 2

L1 or L2

Question 3

What remnant of the spinal cord extends down to the coccyx

Answer 3

Filum terminate internum

Question 4

Where is the cervical enlargement found?

Answer 4

Upper limbs

Question 5

Where is the lumbosacral enlargement found?

Answer 5

Lower limbs

Question 6

What are the main functions of the spinal cord? (2)

Answer 6

1. Main reflex center of the body

2. Interconnects the periphery to the brain

Question 7

What type of tissue is the outer portion of the spinal cord made of?

Answer 7

Peripheral tissue made of white matter

Question 8

What does the peripheral tissue contain?

Answer 8

tracts of ascending and descending axons

Question 9

What type of matter makes up the inside portion of the spinal cord?

Answer 9

gray

Question 10

What does the grey matter contain in the spinal cord?

Answer 10

synapses (dorsal horns, ventral horns, lateral horns

Question 11

Describe the central canal of the spinal cord

Answer 11

Continuous with the ventricles of the brain, filled with CSF

Question 12

Name the meninges of the spinal cord

Answer 12

Dura mater, arachnoid mater, pia mater

Question 13

Describe the dura mater

Answer 13

tough leathery wrapping for the spinal cord

Question 14

Describe the epidural space

Answer 14

Surrounds the bone and is filled with fat, found outside the dura mater

Question 15

What is inside the subarachnoid space?

Answer 15

CSF

Question 16

Which meninge gives the spinal cord its shiny appearance?

Answer 16

pia mater

Question 17

What are denticulate ligaments?

Answer 17

folds of the pia mater that allow it to attach to the dura mater

Question 18

Where in the vertebrae do spinal nerves emerge?

Answer 18

intervertebral foramina

Question 19

How many pairs of spinal nerves are there?

Answer 19

31 pairs: C1-C8; T1-T12; L1-L5; S1-S5, Co1 (not paired)

Question 20

Which spinal nerve is not paired?

Answer 20

Co1

Question 21

About how long are spinal nerves?

Answer 21

1 cm, they immediately branch into other nerves

Question 22

What types of fibers are found in dorsal roots?

Answer 22

sensory

Question 23

What types of fibers are found in ventral roots?

Answer 23

motor

Question 24

What do dorsal roots branch into and where do they synapse?

Answer 24

Branch into dorsal rootlets that synapse into the dorsal horn of the spinal cord

Question 25

What is a dorsal root ganglion?

Answer 25

cluster of cell bodies of sensory neurons

Question 26

Where do ventral rootlets converge?

Answer 26

ventral root

Question 27

Where do somatic motor neurons come from?

Answer 27

Ventral horn

Question 28

Where do autonomic motor neurons come from?

Answer 28

Lateral horn

Question 29

Where are the sympathetic and parasympathetic neurons located respectively?

Answer 29

``` T1-L2 = sympathetic S2-S4 = parasympathetic ```

Question 30

What area of the body do the dorsal rami innervate?

Answer 30

central back

Question 31

What area of the body do ventral rami innervate?

Answer 31

The whole body except for the central back and the head

Question 32

What are the 4 pairs of ventral rami plexuses

Answer 32

Cervical, brachial, lumbar, sacral

Question 33

Describe the cauda equina

Answer 33

spinal cord roots found after L2 that hang down from the spinal cord and exit the vertebral canal from their corresponding vertebrae

Question 34

What region is the cauda equina found and what else is present there?

Answer 34

Lumbar cistern, CSF

Question 35

Describe the short circuit neural pathway

Answer 35

Spinal reflexes, no tracts to or from the brain

Question 36

Describe the full circuit neural pathway

Answer 36

Involves the brain

Question 37

True or false: C1 involves only motor neurons

Answer 37

True: no DRG in C1

Question 38

Describe the pathway for both somatic and visceral sensory input

Answer 38

Peripheral nerves --> spinal nerve rami --> spinal nerve --> dorsal root --> dorsal rootlets --> dorsal horn of spinal cord

Question 39

Describe the pathway for somatic motor input

Answer 39

Ventral horn of spinal cord --> ventral rootlets --> ventral root --> spinal nerve --> spinal nerve rami --> peripheral nerves

Question 40

Describe the first option pathway for sympathetic input

Answer 40

Lateral horn (T1-L2) --> Ventral rootlets --> ventral root --> spinal nerve --> ventral ramus --> white ramus communicantes --> paravertebral ganglion --> synapse onto post-synaptic neuron within the ganglion

Question 41

Describe the second option pathway for sympathetic input

Answer 41

Lateral horn (T1-L2) --> Ventral rootlets --> ventral root --> spinal nerve --> ventral ramus --> white ramus communicantes --> paravertebral gnalgion --> pass through ganglion --> travel up through sympathetic chain --> synapse onto post-synaptic neuron within higher paravertebral ganglion

Question 42

Describe the third option pathway for sympathetic input

Answer 42

Lateral horn (T1-L2) --> Ventral rootlets --> ventral root --> spinal nerve --> ventral ramus --> white ramus communicantes --> paravertebral ganglion --> pass through ganlgion --> travel down through sympathetic chain --> synpase onto post synaptic neuron within lower paravertebral ganglion

Question 43

Describe the fourth option pathway for sympathetic input

Answer 43

Lateral horn (T1-L2) --> Ventral rootlets --> ventral root --> spinal nerve --> ventral ramus --> white ramus communicantes --> paravertebral ganglio --> pass through ganglion --> travel through sympathetic chain --> exit without synapsing --> enter splancnic nerve --> enter prevertebral ganglion --> synapse onto post ganglionic neurons innervating viscera

Question 44

What 4 places do sympathetic nerves travel to?

Answer 44

1. neck, body wall, limbs 2. head 3. thoracic viscera 4. abdominal viscera

Question 45

Describe the pathway of the sympathetics to the neck, body walls and limbs

Answer 45

Post-synaptic cell bodies within paravertebral ganglion --> fibers exit gray ramus communicanted --> enter spinal nerve rami of all 31 spinal nerves

Question 46

What actions are the sympathetics to the head, body wall and limbs responsible for?

Answer 46

vasomotion, pilomotion, sudomotion

Question 47

Describe the pathway of the sympathetics to the head

Answer 47

Post-synaptic cell bodies within superior cervical ganglion --> fibers exit cephalic arterial rami (carotis nerves) --> bind to carotid arteries --> branch and follow various arteries to specific areas in the head

Question 48

What actions are the sympathetics to the head responsible for?

Answer 48

vasomotion, pilomotion, sudomotion, pupillary dilation via the pupillary dilator muscle, xerostomia (salivary gland inhibition)

Question 49

Describe the pathway of the sympathetics to thoracic viscera

Answer 49

post-synaptic cell bodies within superior, middle and inferior (stellate) cervical ganglion and to the thoracic paravertebral ganglia from T1-T5 --> fibers enter cardiopulmonary splancnic nerve (superior, middle, inferior)

Question 50

What do the superior and middle splacnic nerves innervate?

Answer 50

heart

Question 51

What do the inferior splancnic nerves innervate

Answer 51

lungs and other pulmonary structures

Question 52

What actions are the sympathetics to the thoracic viscera responsible for?

Answer 52

increase HR and strength of contraction, vasodilation of coronary arteries, bronchodilation

Question 53

Describe the pathway of the sympathetics to the abdominal viscera

Answer 53

pre-synaptic fibers exit thoracic paravertebral ganglia from T5-L2 --> enter into abdominopelvic splancnic nerve (greater, lesser, least, lumbar) --> synapse onto post-synaptic cell bodies within prevertebral ganglia (celiac, superior mesenteric, aorticorenal, inferior mesenteric) --> fibers exit prevertebral ganglia within small nerve --> abdominal viscera

Question 54

What is the exception to the symapthetic pathway to abdominal viscera

Answer 54

innervation of adrenal medulla: pre-synaptic fibers pass through aorticorenal ganglion and synapse onto cells within adrenal medulla (for epinephrine secretion)

Question 55

What types of fibers are found in cardiopulmonary splancnic nerves

Answer 55

postsynaptic fibers

Question 56

What types of fibers are found in abdominopelvic splancnic nerves

Answer 56

presynaptic fibers

Question 57

Describe the pathway of parasympathetic nerve fibers

Answer 57

Lateral horn (S2-S4) --> ventral rootlets --> ventral root --> exit via pelvic splancnic nerves --> to pelvic organs and leat half of large intestine

Question 58

Where do pelvic splancnic nerves branch from?

Answer 58

ventral rami from ventral rami of S2-S4

Question 59

Where are peripheral ganglia located in regards to target organ?

Answer 59

adjacent to them