Control Lecture 3: Ascending sensory pathways II

Question 1

What are the three divisions of the trigeminal nerve and where do they pass through the skull?

Answer 1

V1: Opthalmic - Superior orbital fissure
V2: Maxillary - Foramen rotundum
V3: Mandibular - Foramen ovale

Question 2

Which nerves supply sensory innervation to the teeth, and which divisions of the trigeminal nerve are they branches of?

Answer 2

Superior and inferior alveolar nerves

Branches of the maxillary and mandibular divisions respectively

Question 3

What is the equivalent of the dorsal root ganglia in facial sensation?

Answer 3

Trigeminal ganglia

Question 4

Where does the first synapse generally occur in a sensory pathway from the face?

Answer 4

Trigeminal sensory nucleus

Question 5

Which cranial nerves provide sensory innervation to the head (and to which specific parts)?

Answer 5

V - Trigeminal (face, lips, teeth)
VII - Facial (external ear, anterior 2/3 of tongue)
IX - Glossopharyngeal (posterior 1/3 of tongue, pharynx, middle ear)
X - Vagus (auditory canal, larynx, pharynx)

Question 6

Which division of the trigeminal sensory nucleus is in the midbrain?

Answer 6

Mesencephalic sensory nucleus

Question 7

Which division of the trigeminal sensory nucleus is in the pons?

Answer 7

Principal/chief/pontine sensory nucleus

Question 8

Which division of the trigeminal sensory nucleus is in the medulla?

Answer 8

Spinal sensory nucleus

Question 9

Do sensory nuclei lie lateral or medial to motor nuclei in the brainstem?

Answer 9

Lateral

Question 10

Will sensory information from the face end up at the inferolateral or the superomedial postcentral gyrus?

Answer 10

Inferolateral

Question 11

Where do the “essential for life” sensation pathways from the face (pain, temp, touch, pressure) have their first cell body?

Answer 11

Trigeminal ganglion

Question 12

Where do the “essential for life” sensation pathways from the face (pain, temp, touch, pressure) have their first synapse?

Answer 12

Spinal nucleus

Question 13

In the pain and temperature pathway, at which pole (caudal/rostral) of the medulla is the first synapse?

Answer 13

Caudal

Question 14

In the touch and pressure pathway, at which pole (caudal/rostral) of the medulla is the first synapse?

Answer 14

Rostral

Question 15

Where do the “essential for life” sensation pathways from the face (pain, temp, touch, pressure) cross the midline?

Answer 15

Medulla

Question 16

What is the name of the tract in which sensory fibres from the face ascend to the thalamus?

Answer 16

Trigeminothalamic tract

Question 17

In what region of the thalamus does the trigeminothalamic tract terminate?

Answer 17

Ventroposteromedial (VPM)

Question 18

Are descending fibres in the spinal tract superficial or deep in the medulla?

Answer 18

Superficial

Question 19

What is more superficial, descending fibres in the spinal tract or ascending fibres in the spinal sensory nucleus?

Answer 19

Descending fibres in the spinal tract

Question 20

Is the trigeminothalamic tract relatively superficial or deep in the brainstem?

Answer 20

Deep

Question 21

What kind of sensation is carried in the lateral lemniscus, which lies close to the spinal tract and spinal nucleus in the medulla, and is it contralateral or ipsilateral?

Answer 21

Pain and temperature (“essential for life”) information from the body - the continuation of the spinothalamic pathway
Contralateral

Question 22

Which division of the trigeminal nucleus receives proprioceptive information?

Answer 22

Mesencephalic nucleus

Question 23

Where is the first synapse located in the proprioceptive pathway from the face?

Answer 23

Medial to the spinal nucleus in the midbrain

Question 24

Which is the only pathway that is an exception to the rule of the first order cell body being located in a peripheral ganglion, and where is it located instead?

Answer 24

Proprioceptive pathway

Mesencephalic nucleus

Question 25

Which division of the trigeminal nucleus receives discriminatory touch information?

Answer 25

Pontine/chief nucleus

Question 26

In what tract does proprioceptive and discriminatory touch information ascend to the thalamus?

Answer 26

Trigeminothalamic

Question 27

Where is the first synapse located in the discriminatory touch pathway?

Answer 27

Pontine/chief nucleus

Question 28

Where is the first order neuron cell body in the discriminatory touch pathway?

Answer 28

Trigeminal ganglion

Question 29

Which monosynaptic reflex pathway has its first order neuron in the proprioceptive pathway and synapses in its ipsilateral motor nucleus in the pons?

Answer 29

Jaw-jerk reflex

Question 30

Which division of the trigeminal nerve carries the most proprioceptive information?

Answer 30

Mandibular (V3)

Question 31

Patient presents with:
A) Loss of pain and temperature sensation from the left side of the body and the right side of the face
B) Loss of pressure and some touch sensation from the right side of the face
C) Proprioception, vibration and discriminatory touch intact all over the body
Where is the lesion and how can you tell?

Answer 31

Right side of the medulla, superficial lesion

• Ipsilateral “essential for life” sensation in descending spinal tract affected
• Contralateral lateral lemniscus from the spinothalamic pathway affected
• Contralateral medial lemniscus from dorsal column pathway unaffected (superficial lesion)
• Discriminatory touch and proprioception from the face unaffected as sensory fibres enter higher up the brainstem