Pain pathways of head and neck and reflexes

Question 1

Describe the route of the ascending pain pathway

Answer 1

Synapses in the dorsal horn of the spinal cord and decussates, ascends contra laterally to the ventral posterior nucleus of the thalamus, tot he sensory cortex

Question 2

Describe the route of the descending pathway that inhibits pain

Answer 2

Originates for periaqueductal grey in the midbrain.

Synapses in the nucleus raphe in the medulla, onto the spinal cord where it inhibits pain pathways by interneurones

Question 3

To what nuclei does the corticobulbar fibres provide bilateral innervation?

Answer 3

V and VII (upper face), XII except for genioglossus which is contralateral

Question 4

To what nuclei does the corticobulbar fibres provide contralateral innervation?

Answer 4

VII lower face

Question 5

To what nuclei does the corticobulbar fibres provide ipsilateral innervation?

Answer 5

XI

Question 6

To which nuclei do corticobulbar fibres provide contralateral innervation from frontal and parietal eye fields?

Answer 6

II, IV, VI

Question 7

What does the trgeminal nerve provide sensory innervation in the head and neck to?

Answer 7

Muscle of facial expression, nose, orbit, meninges,

Question 8

Through what nerve do pain afferents form the ear canal travel?

Answer 8

VII

Question 9

Through what nerve do pain afferents from posterior 1/3 of tongue travel?

Answer 9

IX

Question 10

What fibres transmit sharp pain from teeth?

Answer 10

A fibres

Question 11

Why can changes in temperature to teeth cause pain?

Answer 11

A fibres can extend into dentinal tubules

Question 12

What fibres transmit dull aching pain from teeth?

Answer 12

C fibres

Question 13

To which nucleus does all pain from he head and neck synapse?

Answer 13

Spinal root of V

Question 14

Where are the sensory aspects fo pain processed?

Answer 14

Somatosensory cortex

Question 15

Where are the emotional aspects of pain processed?

Answer 15

Anterior cingulate cortex

Question 16

What is the periaqudeuctal gray?

Answer 16

Nucleus around cerebral aqueduct within the tegmentum

Question 17

What neurotransmitters are released by the inhibitory neurones?

Answer 17

Serotonin

Question 18

Describe the route of the trigemino-reticular thalamic pathway

Answer 18

From spinal nucleus of V to reticular formation to thalamus

Question 19

What is the function of the trigemino-reticular thalamic pathway?

Answer 19

Mediates painful stimuli vis interneurones for withdrawal reflexes

Question 20

What is the corneal reflex?

Answer 20

Touch cornea of 1 eye causes a bilateral blink

Question 21

What is the route of the corneal reflex?

Answer 21

Sensory via V1 to spinal nucleus of V to facial toro nucleus to orbicularis oris

Question 22

What is the gag reflex?

Answer 22

Touch back of oropharynx causes elevated palate and contraction of pharynx = gag

Question 23

What is the route of the gag reflex?

Answer 23

Sensory via IX to nucleus of solitary tract to nucleus ambiguous to X

Question 24

What is the jaw jerk reflex?

Answer 24

Head and neck stretch reflex makes jaw close

Question 25

What is the route of the law jerk reflex?

Answer 25

Sensory via V3 to mesencephalic nucleus of V to motor nucleus of V to massater

Question 26

What is the jaw-unloading reflex?

Answer 26

Head and neck Golgi tendon reflex - unloading of stretch on periodontal ligament to inhibit massater activity

Question 27

What is the route of the jaw-unloading reflex?

Answer 27

Sensory via V3 to mesencephalic nucleus of V to motor nucleus of V to massater (inhibitory)