H&N 3: Cranial Nerve Overview #1 Flashcards
List the cranial nerves
I - Olfactory II - Optic III - Oculomotor IV - Trochlear V - Trigeminal VI - Abducens VII - Facial VIII - Vestibulocochlear IX - Glossopharyngeal X - Vagus XI - Accessory XII - Hypoglossal
Where do sensory fibres carry and take info?
- through peripheral branch into DRG
- then through central branch to dorsal horn
What is function of dorsal root entry zone?
- afferent
- receives sensory info from periphery dep on type of info e.g. pain, proprioception etc to higher centres through thalamus
What is function of ant. grey horn?
receives motor info from periphery
What is contained in DRG?
Sensory cell bodies
How can you perform actions?
- cell bodies in cerebral cortex in brain + corticospinal tract form many fibres from motor cortex going down to synapse at ventral horn of spinal cord
- then fibres go to muscles for movement
What are the fibres in the head and neck?
- corticobulbar
- motor fibres synapsing on motor nuclei in brain stem of cranial nerves
What type of fibres are motor + sensory?
- sensory: asc + dorsal
- motor: desc + ventral
What links the CNS to the periphery?
- cranial & spinal nerves
What do cranial & spinal nerves attach to?
- cranial nerves attach to forebrain + brain stem
- spinal nerves attach to spinal cord
What are the features of cranial nerves?
- ganglia
- no synapses
- no DRG but gang of particular cranial nerve e.g. trigeminal ganglia
- have sensory/motor nuclei
Where are I-IV located?
- ant. portion of the brain
- III from front of pons
Where are V-VII arise?
- pons
- V from middle
- VI from back
- VII + VIII from cortico-pontine angle
Where does VIII arise and go?
inner ear and goes to pons
Where does IX-XII attach?
- medulla oblongata
- XII from pyramid
What do asc + desc fibres of pons pass through?
- cortico-pontine angle
What comes down the pyramid?
big cortico-spinal trunk
What is optic chiasm?
where optic nerves cross over
Describe 1st + 2nd order neurones
- synapse in CNS
- then sensory afferent in PNS
Describe skeletomotor neurones
- cell bodies in CNS
- then somatic efferent (motor) to muscles
Describe pre + postgang neurones
- synapse in CNS + PNS
- then somatic (visceral) to glands
List special sensory/afferent only cranial nerves
I, II, VIII
List efferent/motor only cranial nerves
III, IV, VI, XI, XII
List afferent/efferent cranial nerves
V, VII, IX, X
Which 4 cranial nerves have auto component?
- III, VII, IX, X
- carry ‘cranial’ part of craniosacral auto/para outflow from CNS
What is functional component of cranial nerves?
- chewing + swallowing (tasting + smelling)
- talking
- looking
- non-verbal comm (facial expression)
- hearing
Which areas give sensation by cranial nerves?
- cutaneous: scalp, face + neck
- non-cutaneous: oral cavity (mucosa, teeth + tongue), cornea, nasal cavity + paranasal sinuses, pharynx, larynx, tympanic mem
- articular: TMJ, cervical vert, atlantoocipital joint
Which areas do cranial nerves give motor supply?
- muscles of facial expression
- muscles of mastication
- extra-ocular muscles
- muscles of tongue
- muscles of pharynx + larynx
- cervical muscles
What auto supply do cranial nerves also supply?
carry auto supply of glands + smooth muscle in ehead + neck
Which reflexes are cranial nerves involved in?
- visual (pupillary, blink, accomm)
- auditory
- swallowing
- gagging, vom
- sneezing, coughing
List functions of I-III
I - sensory fibres to nose for smell
II - sensory fibres to eye for visual acuity, visual fields + ocular fundi
II, III - Pupillary reactions
Which nerves are involved in extra-ocular movements inc opening eyes?
III, IV, VI
What is function of V?
- sensory supply to face for facial sensation
- sensory supply for movements of jaw
- corneal reflexes
- motor supply to muscles of mastication
What are functions of VII + VIII?
VII - facial movements + gustation (ant. 2/3 tongue)
VIII - hearing + balance
What are functions of IX + X?
- swallowing
- elevation of palate
- gag reflex
- gustation (post. 1/3 tongue)
