Cranial Nerves Flashcards
What modality is the olfactory nerve?
sensory
Where are the only neurones in the body that are exposed to the outside world?
Olfactory nerve
Where does the olfactory nerve arise?
Forebrain
Where does the olfactory nerve enter the skull?
Cribriform plate of the ethmoid bone
What cranial nerve controls sense of smell?
Olfactory nerve (CN I)
What is CN I?
Olfactory nerve
What is CN II?
Optic nerve
What cranial nerve controls sight?
Optic nerve (CN II)
What modality is CN II?
Sensory
Where does CN II arise?
Forebrain
Where does CN II enter the skull?
Optic canal
How can you test CN II?
light reflexes visual field testing Snellen chart
What is CN III?
Oculomotor
What muscles are supplied by CN III?
inferior, superior and middle rectus inferior oblique levator palpebrae superioris (LPS)
What is the parasympathetic action of CN III/oculomotor nerve?
Supplies sphincter papillae and ciliary muscle
Where does the oculomotor nerve arise?
Midbrain
Where does CN III leave the brain?
superior orbital fissue
Describe a third nerve palsy.
Ptosis (as CN III supplies LPS which elevates upper eyelid) Large pupil (as CN III supplies sphincter papillae which constricts pupil) Eye down and out
What is cranial nerve IV?
Trochlear
How can you test CN III?
Eye movements
What modality is CN IV?
motor
What muscle is supplied by CN IV?
Superior oblique
Where does the trochlear nerve leave the skull?
Superior orbital fissure
Describe a fourth nerve palsy.
Diplopia on looking down and in
How can you test CN IV?
Eye movements
What is CN V?
Trigeminal
What is the sensory function of CN V?
Facial sensation
What are the 3 divisions of CN V?
1 - ophthalmic 2 - maxillary 3 - mandibular
What cranial nerve enters the skull via foramen rotundum?
CN V2 (maxillary)
What cranial nerve enters/exits the skull via foramen oval?
CN V3 (mandibular)
Where does CN V1 enter the skull?
superior orbital fissure
What muscles are supplied by the trigeminal nerve?
muscles of mastication - masseter, temporalis, medial and lateral pterygoid tensor tympani mylohyoid tensor veli palatini
How do you test CN V?
Facial sensation Powers of muscles of mastication
What is CN VI?
Abducens
What muscle is supplied by CN VI?
lateral rectus
Describe a CN VI palsy.
horizontal diplopia looking out
Where does the abducens nerve leave the skull?
superior orbital fissure
What cranial nerve is the facial nerve?
CN VII
What muscles are supplied by the facial nerve?
Muscles of facial expression Stapedius Stylohyoid
What is the sensory function of CN VII?
Taste from anterior 2/3rds of tongue via chorda tympani
What is the parasympathetic innervation of the submandibular and sublingual glands?
CN VII
Where does CN VII enter and exit the skull?
Internal acoustic meatus
How can you test the facial nerve?
Raise eyebrows Puff out cheeks Show teeth
What is CN VIII?
vestibulocochlear
What CN controls hearing?
CN VIII
What tests can you do to test CN VIII?
Rhinnes and Webers
Where does the vestibulocochlear nerve enter the skull?
Internal acoustic meatus
What CN is the glossopharyngeal nerve?
CN IX
What is the sensory function of CN IX?
Taste from posterior third of tongue
What muscle is supplied by CN IX?
Stylopharyngeus
What salivary gland does CN IX supply?
Parasympathetic innervation of parotid gland
What two cranial nerves make the gag reflex?
CN IX and X
Where does CN IX enter and exit the skull?
Jugular foramen
What is CN X?
Vagus
What CN supplies sensory and motor to the structures of the larynx?
CN X
What is the parasympathetic supply to the abdominal and thoracic viscera?
CN X
How does the vagus nerve travel in the neck?
in the carotid sheath
What is the course of the vagus nerve in the chest?
R - lateral aspect of trachea, posterior to hilum of lung, passes through diaphragm with oesophagus L - lateral aspect of aortic arch, crosses arch of aorta, posterior to hilum of lung and passes through diaphragm with oesophagus
How can you test CN X?
- patient say ‘ah’ (uvula goes away from abnormal side) - patient swallow some water (splutter?) - hoarseness? (abnormality of muscles of larynx?)
What is CN XI?
Spinal accessory
What muscles are supplied by the spinal accessory nerve?
Sternocleidomastoid Trapezius
How does CN XI leave the skull?
Jugular foramen
How do you examine CN XI?
shrug shoulders - tests trapezii turn head to left and right against resistance - tests sternocleidomastoid
What CN is the hypoglossal nerve?
CN XII
How does the hypoglossal nerve leave the skull?
hypoglossal canal
What does CNXII supply?
Muscles of the tongue (except palatoglossal - vagus)
How do you examine CN XII?
Stick tongue straight out (unilateral pathology - tongue deviates towards)
What is the afferent/efferent parts of the pupillary reflex?
afferent - CN II efferent - CN III
Label this cranial nerve.
olfactory (CN I)
Label this cranial nerve
optic nerve CN II
Label
CN III occulomotor
label
trochlear CN IV
label
CN V1,2,3 - trigeminal
label
CN VI - abducens
label
CN VII - facial
Label
CN VIII - vestibulocochlear
label
CN IX - glossopharyngeal
lavel
CN X - vagus
label
CN XI - spinal accessory
label
CN XII - hypoglossal
Label
WHat is the afferent limb of the corneal reflex?
CN V1
What is the efferent limb of the corneal reflex?
CN VII
What is the afferent limb of the gag reflex?
CN IX
What is the efferent limb of the gag reflex?
CN X
Which foramen does the internal carotid go through?
foramen lacerum
Which foramen does the middle meningeal go throguh?
foramen spinosum
