PDF - CN / Reflexes Flashcards
Which is CN I?
Olfactory
Which is CN II?
Optic
Which is CN III?
Occular Motor
Which is CN IV?
Trochlear
Which is CN V?
Trigeminal
Which is CN VI?
Abducens
Which is CN VII?
Facial
Which is CN VIII?
Vestibulocochlear
Which is CN IX?
Glossopharyngeal
Which is CN X?
Vagus
Which is CN XI?
Spinal Accessory
Which is CN XII?
Hypoglossal
Which is the olfactory Nerve?
I
Most common cause impaired swallowing?
Mucosal swelling / inflammation during sinusitis or an
URI
Cerebral causes loss of smell?
- Trauma: olfactory nerve branches sheared where they pass through the cribriform plate
- Tumor - near olfactory lobe at the skull base (meningioma)
Which is the optic nerve?
II
Which is the oculomotor nerve?
III
Role of Superior and Inferior Obliques?
Superior oblique: depresses and abducts eye
Inferior oblique: elevates and abducts eye
What innervates the lateral rectus?
CN VI
What innervates Superior Oblique?
CN IV
What may be weak if elevation of Eye is incomplete?
She superior rectus or inferior oblique (or both)
- When eye adducted, weakness of elevation mainly due to the inferior oblique
- When teye abducted, weakness of elevation mainly due to the superior rectus
* **Same true with inferior rectus and oblique
Presentation complete CNII lesion?
- Ptosis (paralysis levator palpebrae)
- Impacted eye ABducted (Unopposed LR)
- Pupil large and unreactive
Types of lesions causing nystagmus?
- Vestibular system
- Brain stem
- Cerebellum
Difference between drug induced nystagmus and pathological?
Drug: symmetrically seen in all directions
Path: Only seen with certain movements
Most common cause MLF (INO Lesions)?
Young: multiple sclerosis
Older: ischemic infarction
Presentation INO?
Eyes can accommodate, but when move to one vision field, the contralateral eye cannot ADduct
What is happening in INO
- Lack of communication such that when CN VI nucleus activates ipsilateral lateral rectus, contralateral CN III nucleus does not stimulate medial rectus to fire.
- Abducting eye gets nystagmus (CN VI overfires to stimulate CN III). Convergence normal.
What does MLF do?
Communicates between nuclei of CNIII and CNVI