Cranial Nerves

Question 1

What are the purely sensory cranial nerves?

Answer 1

Olfactory, optic, vestibulocochlear

Question 2

What are the purely motor cranial nerves?

Answer 2

Oculomotor, trochlear, aducens, accessory spinal, hypoglossal

Question 3

What are the cranial nerves with mixed modalities?

Answer 3

Trigeminal, facial, golssopharyngeal, vagus

Question 4

Where do cranial nerves provide motor and sensory innervation?

Answer 4

The head (exception is vagus nerve)

Question 5

Where do the cranial nerves exit the cranial vault?

Answer 5

All exit anteriorly, except CN IV which exits posteriorly and CN VIII which exits laterally

Question 6

What is each sensory or motor component associated with?

Answer 6

A streak of grey matter in the brain/brainstem which serves on function

Question 7

What are motor components associated with?

Answer 7

Motor nuclei = groups of efferent nerve cells that send their axons into the cranial nerve

Question 8

What are sensory components associated with?

Answer 8

Sensory nuclei = groups of nerve cells upon the sensory neurons of the cranial nerves synapse

Question 9

Where are the soma of sensory nerve cells found?

Answer 9

In ganglia outside of the CNS

Question 10

What is the only sensory modality that doesn’t synapse in the thalamus prior to reaching the cotex?

Answer 10

Olfactory nerve

Question 11

Where is the nuclei origin of motor cranial nerves?

Answer 11

Near the midline = all emerge close to midline which reflect location of their nucleus

Question 12

What are some features of the oculomotor nerve?

Answer 12

Somatic motor and parasympathetic

Relates to Edinger-Westphal and oculomotor nucleus

Question 13

What muscles does the oculomotor nerve supply with sympathetic fibres?

Answer 13

Sphincter pupillae and ciliary muscles

Question 14

What are some features of the trochlear nerve?

Answer 14

Somatic motor
Crosses midline
Nucleus in lower midbrain

Question 15

What are some features of the abducens nerve?

Answer 15

Somatic motor

Located in the caudal pons

Question 16

What are some features of the hypoglossal nerve?

Answer 16

Somatic motor

Located in the medulla

Question 17

Where does the spinal accessory nerve originate?

Answer 17

From the cervical spinal cord

Question 18

What are the functions of the trigeminal nerve?

Answer 18

Somatosensation of face
Proprioception associated with chewing
Motor = muscles of mastication, tensor tympani, mylohyoid, anterior belly of digastric, tensor veli palatini

Question 19

What nuclei are associated with the trigeminal nerve?

Answer 19

Mesencephalic nucleus, pontine trigeminal nucleus, spinal nucleus, sensory nucleus, ventral trigeminothlamic tract

Question 20

What are some features of the mesencephalic nucleus?

Answer 20

Carries proprioception info from chewing muscles

Located close to jaw

Question 21

What is special about the mesencephalic nucleus?

Answer 21

Only site in CNS where cell bodies of primary afferent neurons live in the CNS

Question 22

What information is the pontine trigeminal nucleus responsible for?

Answer 22

Discriminative touch and vibration

Question 23

What information is the spinal nucleus responsible for?

Answer 23

Pain and temperature

Question 24

What does the sensory nucleus of the trigeminal nerve form?

Answer 24

Long column of neuron that stretches from midbrain down to upper 2 segments of cervical spinal cord

Question 25

How does the ventral spinothalamic tract allow bilateral representation of touch in the cortex?

Answer 25

Most fibres cross the midline but some don't

Question 26

What are the functions of the facial nerve?

Answer 26

Motor to muscles of facial expression Parasympathetic to pterygopalatine and submandibular ganglia Taste to anterior 2/3 tongue

Question 27

What are the functions of the glossopharyngeal nerve?

Answer 27

Tactile sense, pain and temperature from tongue, Eustachian tube and upper pharynx Taste to posterior 1/3 tongue Parasympathetics to otic ganglion Motor to stylopharyngeus

Question 28

How many components does the facial nerve have?

Answer 28

3

Question 29

What are the functions of the vagus nerve?

Answer 29

Tactile sense, pain and temperature form pharynx, larynx, trachea, oesophagus and viscera Taste from epiglottis Parasympathetic to ganglia of thoracic and abdominal viscera Motor to striated muscle of pharynx and larynx

Question 30

What nerve besides CN X contributes to the motor innervation of the striated muscle of the pharynx and larynx?

Answer 30

Spinal accessory nerve

Question 31

What are the components of the glossopharyngeal nerve?

Answer 31

Gustatory nucleus, spinal trigeminal nucleus, inferior salivary nucleus, nucleus ambiguus

Question 32

What are the components of the vagus nerve?

Answer 32

Dorsal nucleus, solitary tract, spinal trigeminal nucleus, nucleus ambiguus

Question 33

What are the three complex cranial nerves?

Answer 33

Facial nerve, glossopharyngeal nerve and vagus nerve

Question 34

What cranial nerves share the solitary nuclei?

Answer 34

CN VII, IX and X = taste and visceral sensory info

Question 35

What cranial nerves share the superior and inferior salivary nuclei?

Answer 35

CN VII and X = parasympathetic efferents to ganglia of salivary glands and pterygopalatine ganglion

Question 36

What cranial nerves share the nucleus ambiguus?

Answer 36

CN IX and X (and cranial part of XI) = motor efferents to muscles of pharynx, larynx and upper oesophagus

Question 37

What is the corticobulbar tract?

Answer 37

Part of the pyramidal tract that is motor to cranial nerves = includes fibres to motor nuclei of CN V, VII, X and XII

Question 38

How are the inputs from the corticobulbar tract to the facial nucleus organised?

Answer 38

Only bilateral to part of nucleus that controls upper part of face = only crossed input reaches part of nucleus that controls lower half of face

Question 39

How is the motor input to the cranial nerves innervating extra-ocular muscles organised?

Answer 39

Complex interplay from frontal and parietal lobes, reticular formation, visual cortex and vestibular system

Question 40

How is the input to cranial nerves containing parasympathetic efferents organised?

Answer 40

Input mainly from the hypothalamus whose efferents reach the preganglionic autonomic neurons both directly and via synapses in the reticular formation

Question 41

What is the hypothalamus influenced by?

Answer 41

Physiological status and input from many brain regions

Question 42

What is the reticular formation?

Answer 42

Network of loosely aggregated cells with cell bodies, axons and dendrites intermingling in the central core of the brainstem

Question 43

What is the reticular formation distinct from?

Answer 43

Long pathways and specific distinct cell groups

Question 44

What are the functions of the centres included in the reticular formation?

Answer 44

Integrate cranial nerve reflexes Influence voluntary movement Participate in conduction and modulation of pain Regulate autonomic centres Integrate some basic functions (e.g respiration) Activates cerebral cortex

Question 45

What is the reticular formation a major component of?

Answer 45

The ascending reticular activating system