Cranial Nerves Flashcards
Basic summary of olfactory nerve:
- CN 1
- Provides special visceral afferent fibres for smell
- Connects to brain (not brainstem)
- Passes through cribriform plate of skull
Basic summary of optic nerve:
- CN 2
- Provides special somatic afferent fibres for vision
- Connects to brain
- It is the afferent limb for the pupillary light reflex
- Passes through the optic canal of skull
Basic summary of oculomotor nerve:
- CN 3
- Provides somatic efferent and general visceral efferent fibres to the extra-ocular muscles and pupillary constrictor muscles respectively
- Muscles are levator palpebrae superioris, inferior oblique and superior, medial and inferior recti
- CN 3 damage causes down and out eye
- Connects to midbrain
- Efferent limb for pupillary light reflex
- Passes through superior orbital fissure of skull
Basic summary of trochlear nerve:
- CN 4
- Provides general somatic efferent to extra-ocular superior oblique muscle
- Assists in depressing and abducting the eye
- Connects to the midbrain and is only cranial nerve to leave pontomesencephalic junction POSTERIORLY
- Passes through superior orbital fissure of the skull
Basic summary of trigeminal nerve:
- CN 5
- Has 3 sensory nuclei
- Mesencephalic- proprioception
- Principal- light touch and discrimination
- Spinal- pain, temperature, crude touch
- Emerges from the pons
- Afferent limb of the corneal reflex (CN 7 is bilateral efferent limb)
What are the 3 divisions of the trigeminal nerve?
Ophthalmic (V1)
- modality: general somatic afferent
- sensory function: above the lower eyelid
- motor function: nil
- foramen: superior orbital fissure
Maxillary (V2)
- modality: general somatic afferent
- sensory function: lower eyelid to upper lip
- motor function: nil
- foramen: foramen rotundum
Mandibular (V3):
- modality: general somatic afferent and special visceral efferent
- sensory function: below lower lip
- motor function: muscles of mastication
- foramen: foramen ovale
Basic summary of abducens nerve:
- CN 6
- Originates in the pontomedullary region
- Provides general somatic efferent fibres for eye abduction
- Innervates the lateral rectus muscles
- Passes through the superior orbital fissure of skull
Basic summary of facial nerve:
- CN 7
- Originates in the pontomedullary region
- Loops around the abducens nerve
- Passes through internal auditory meatus and exits through the stylomastoid foramen
- LMN facial nerve lesions cause upper and lower facial paralysis
- UMN facial nerve lesions cause lower facial paralysis only
What structures are innervated by the facial nerve?
General somatic efferent: skin behind the ear
Special visceral afferent: taste to the anterior 2/3 of the tongue
General visceral afferent: parasympathetic to lacrimal, sublingual and submandibular glands
Special visceral efferent: muscles of facial expression
Basic summary of vestibulocochlear nerve:
- CN 8
- Originates in the pontomedullary region
- Provides special somatic afferent fibres for hearing and balance
- Cochlea transmits sound waves to mechanical ossicle movements to electrochemical action potentials
- The vestibular apparatus detects change in head motion
- Passes through internal auditory meatus and does not leave skull
Basic summary of glossopharyngeal nerve:
- CN 9
- Originates in medulla oblongata
- Draws fibres from solitary nucleus (taste) and nucleus ambiguus (motor)
- Draws more fibres from the inferior salivatory nucleus (parotid gland) and dorsal motor nucleus (DMX; pharyngeal sensation)
- Passes through jugular foramen
What structures are innervated by the glossopharyngeal nerve?
General somatic afferent: sensation from the posterior 1/3 of tongue, pharynx
Special visceral afferent: taste to posterior 1/3 of tongue
General visceral efferent: parasympathetic to parotid glands
Special visceral efferent: motor to stylopharyngeus
Basic summary of vagus nerve:
- CN 10
- Originates in the medulla oblongata
- Major role is parasympathetic innervation of the viscera
- Recurrent laryngeal nerve loops under the RCA and (L)aortic arch
- Passes through the jugular foramen with 9 and 11
What structures are innervated by the vagus nerve?
General somatic afferent: skin around ear
Special visceral afferent: taste and sensation to epiglottis
General visceral efferent: parasympathetic to glands of GI tract
Special visceral efferent: motor innervation to soft palate, pharynx and larynx
Basic summary of accessory nerve:
- CN 11
- Originates in medulla oblongata and superior cervical cord region
- Provides general somatic efferent fibres to the trapezius and SCM
- Exits the spinal cord and enters the skull through the foramen magnum
- Then leaves skull at jugular foramen
