Nervous system and pain

Question 1

Which branches of body structures need innervation?

Answer 1

Somatic (skin, bones, parietal membranes), visceral/splanchnic (organs), branchial arches (head and neck)

Question 2

Which motor neurons innervate the different branches of structures?

Answer 2

Somatic - spinal nerves (segmental and non); Visceral - Autonomic nervous system (sympathetic T1-L2 and parasymp. in certain cranial nerves); branchial arches - cranial nerves

Question 3

Which sensory neurons innervate the different branches of structures?

Answer 3

Somatic - spinal nerves (segmental and non), sharp localized pain; Visceral - Autonomic nervous system (visceral afferents), respond to stretch and ischemia, dull delocalized pain; branchial arches - cranial nerves

Question 4

Know the spreadsheet on slide 1

Answer 4

Spreadsheet

Question 5

Where do different neurons reside in spinal cord?

Answer 5

Motor - ventral horn; sensory - dorsal horn; sympathetic - lateral horn (where applicable)

Question 6

Spinal nerve definition

Answer 6

Union of the dorsal root and ventral root. Arise from spinal cord, 31 pairs.

Question 7

Dorsal root

Answer 7

Sensory, combo from the dorsal and ventral rami sensory neurons.

Question 8

Dorsal ramus

Answer 8

Splits off spinal root. All segmental. Contain sensory and motor fibers, and sympathetic between T1-L2/3

Question 9

Ventral ramus

Answer 9

Same as dorsal, except only T1 to T2 are segmental.

Question 10

Nerve plexuses

Answer 10

Formed by fusion of central primary rami that are non segmental

Question 11

What do spinal nerves innervate?

Answer 11

Somatic structures (body wall, extremities) structures: skin, skeletal muscle, bone, parietal membranes; then become cutaneous (more superficial) to supply dermatomes

Question 12

Why do spinal nerves have sympathetic fibres?

Answer 12

Sympathetic needed for smooth muscles in blood vessels, sweat glands,

Question 13

Dermatome

Answer 13

band of skin with its own sensory innervation

Question 14

Draw a picture of a spinal nerve

Answer 14

Picture

Question 15

Draw diagram of the branches of the nervous system

Answer 15

Diagram

Question 16

Fibres used for sensory, and sympathetic and parasympathetic motor branches

Answer 16

Sensory - visceral afferent; sympathetic - thoracolumbar outflow; parasympathetic - craniosacral

Question 17

Somatic motor system

Answer 17

Single neuron goes from CNS to muscle

Question 18

Autonomic motor system

Answer 18

2 neuron system. Preganglionic neuron leaves CNS, then synapses in autonomic ganglion, then postganglionic neuron goes to targets

Question 19

Sympathetic nervous system neurons

Answer 19

Preganglionic neuron is short (Ach), post gang. is long (Norepinephrine) or can be short and then transmit via blood vessel to target (Epi and norepi)

Question 20

Parasympathetic nervous system neurons

Answer 20

Preganglionic neuron is long (Ach), post gang. is short (Ach)

Question 21

Draw diagrams to compare sympathetic and parasympathetic pathways

Answer 21

Two things.

Question 22

What options do preganglionic sympathetic neurons get to different targets?

Answer 22

Start in T1-L2/3, go enter white ramus communicans then paravertebral sympathetic chains, then there are 5 options.

Question 23

1

Answer 23

Go in white, then come out grey rams communicans then goes out spinal nerves at same level.

Question 24

2

Answer 24

Synapses at same level, then goes up the paravertebral sympathetic chains then exit in grey ramus into spinal nerve at another level

Question 25

3

Answer 25

Synapses at same level, then goes up the paravertebral sympathetic chains then exit in direct branch to thoracic organs (from T1 to T5)

Question 26

4

Answer 26

Preganglionic neuron doesn’t synapse at own level, but synapse s in superior cervical ganglion (SCG) then goes to head and neck. All head and neck from T1-T5.

Question 27

5

Answer 27

Goes through the chain along splanchnic nerve to prevertebral ganglia along blood vessel (at base of arteries), synapses, then supplies sympathetic fibres to abdomen

Question 28

Outline pathways of the 5 options

Answer 28

Crazy diagram with 5 options

Question 29

How do visceral afferent pain fibres return from abdomen and thorax to CNS?

Answer 29

Return along splanchnic nerves, enter the paracertenral sympathetic chain, leave the chain and enter spinal nerve, cell body is in dorsal root ganglion, then enter spinal cord and go to the cortex of brain.

Question 30

Another name for T1-L2/3

Answer 30

Intermediolateral cell column (IML). This is where the pre-ganglionic sympathetic neurons come from, then postganglionic use the sympathetic chain to access all extremities

Question 31

Parasympathetic nervous system summary

Answer 31

Leave brain from cranial nerves III, VII, IX and X, and sacral nerves II, III, IV

Question 32

Types of pain

Answer 32

DIRECT (cutaneous or superficial pain) or REFERRED (indirect, deep pain)

Question 33

Types of referred pain

Answer 33

Somatic - due to embryological displacement or projection. Visceral pain is always referred b/c brain doesn’t have visceral map, always misinterpreted

Question 34

Direct pain

Answer 34

Sharp, easily localized. Carried by spinal nerves which respond to all stimuli. Perceived as arising directly from the injured site

Question 35

Referred pain

Answer 35

From injured structure but perceived as arising from somewhere else, usually dermatome supplied by same spinal segments as the injured structure .

Question 36

Describe somatic referred pain and reasons for it

Answer 36

Spinal nerves, sharp and easily localized. Referred for 2 reasons: 1. Embryological displacement (eg. diaphragm is supplied by C3,4,5 - but referred pain is felt in shoulder because same nerves). 2. Anytime you injure a nerve anywhere along its length, pain is projected or referred to the end of that nerve (eg. funny bone [ulnar nerve], prolapsed disc (sciatica), sinusitis, phantom pain)

Question 37

Describe visceral referred pain and reasons for it

Answer 37

Carried by visceral nerves, which respond to stretch, ischemia, chemoreceptors. Dull and delocalized. Brain perceives pain from somatic structures supplied by same spinal cord levels

Question 38

How would you differentiate b/w appendicitis and cholecystitis in a pregnant woman?

Answer 38

The initial pain will be referred lower in appendicitis. The acute somatic pain will be in the same place.