Cranial nerves Flashcards
What is cranial nerve I?
Olfactory nerve
What is the pathway of cranial nerve I? (3)
- Olfactory mucosa
- Cribriform plate (ethmoid bone)
- Olfactory bulbs to tracts
Where are the nuclei for cranial nerve I?
Forebrain/cerebral hemisphere
What is the exit point of cranial nerve I?
Cribriform plate
What is the function of cranial nerve I?
Sensory - smell
What is cranial nerve II?
Optic nerve
What is the pathway of cranial nerve II? (3)
- Ganglion cells in the retina
- Leaves orbit via optic canal of sphenoid bone
- Optic chiasm
Where are the nuclei of cranial nerve II?
Forebrain/diencephalon
What is the exit point of cranial nerve II?
Optic canal
What is the function of cranial nerve II?
Sensory - vision
What is cranial nerve III?
Oculomotor nerve
What is the pathway of cranial nerve III? (3)
- Arises from brainstem
- Passes through cavernous sinus
- Enters orbit via superior orbital fissure and divides into superior and inferior positions
Where are the nuclei for cranial nerve III?
Midbrain
What is the exit point of cranial nerve III?
Superior orbital fissure
What is the function of cranial nerve III?
Motor - 4 extrinsic eye muscles, levator palpebrae superioris and pupillary sphincter
What is cranial nerve IV?
Trochlear nerve
What is the pathway of cranial nerve IV? (4)
- Arises from brainstem
- Goes through subarachnoid space
- Pierces the dura to enter the cavernous sinus
- Enters the orbit via the superior orbital fissure
Where are the nuclei for cranial nerve IV?
Mibrain
What is the exit point of cranial nerve IV?
Superior orbital fissure
What is the function of cranial nerve IV?
Motor - superior oblique muscle
What is cranial nerve V?
Trigeminal nerve
What are the divisions of the trigeminal nerve? (3)
- Ophthalmic
- Maxillary
- Mandibular
What is the pathway of cranial nerve V? (2)
- Arises from brainstem
- Forms the trigeminal ganglion near the apex of the temporal bone before dividing into 3 divisions
Where are the nuclei of cranial nerve V?
Pons
What is the exit point for cranial nerve V?
- Ophthalmic portion: superior orbital fissure
- Maxillary portion: foramen rotundum
- Mandibular portion: foramen ovale
What is the function of cranial nerve V?
- Ophthalmic portion: sensory (scalp, forehead, nose)
- Maxillary portion: sensory (cheeks, lower eyelid, nasal mucosa, upper lip, upper teeth and palate)
- Mandibular portion: sensory (anterior 2/3 tongue, skin over mandible and lower teeth) and motor (muscle of mastication)
What is cranial nerve VI?
Abducens nerve
What is the pathway of cranial nerve VI?
- Junction between pons and medulla
- Subarachnoid space
- Pierces dura to enter cavernous sinus
- Superior orbital fissure
What is the exit point of cranial nerve VI?
Superior orbital fissure
What is the function of cranial nerve VI?
Motor - lateral rectus muscle
Which cranial nerve causes strabismus (cross-eyed) when damaged?
Cranial nerve VI - abducens nerve
What is cranial nerve VII?
Facial nerve
What is the pathway of cranial nerve VII?
- Junction between pons and medulla
- Internal acoustic meatus
- Facial canal of temporal bone
Where are the nuclei for cranial nerve VII?
Junction between pons and medulla
What is the exit point of cranial nerve VII?
Internal acoustic meatus
What is the function of cranial nerve VII?
- Motor: muscles of facial expression, lacrimal, submandibular, sublingual and mucosal glands
- Sensory: external ear and taste from anterior 2/3 tongue, hard and soft palate
Which cranial nerve causes Bell’s palsy when damaged?
Cranial nerve VII - facial nerve
What is Bell’s palsy? (2)
- Drooping on one side of the face
- Different to a stroke because forehead also droops in Bell’s palsy
What is cranial nerve VIII?
Vestibulocochlear nerve
What is the pathway of cranial nerve VIII? (2)
- Junction between pons and medulla
- Internal acoustic meatus where it splits into vestibular and cochlear nerve
Where are the nuclei of cranial nerve VI?
Junction between pons and medulla
Where are the nuclei of cranial nerve VIII?
Junction between pons and medulla
What is the exit point of cranial nerve VIII?
Internal acoustic meatus
What is the function of cranial nerve VIII?
Sensory - hearing and balance
What is cranial nerve IX?
Glossopharyngeal nerve
What is the pathway of cranial nerve IX?
- Medulla
- Posterior cranial fossa
Where are the nuclei of cranial nerve IX?
Medulla
What is the exit point of cranial nerve IX?
Jugular foramen
What is the function of cranial nerve IX?
Both: posterior 1/3 tongue, external ear, middle ear, carotid body, carotid sinus, parotid gland, motor to stylopharyngeus
What is cranial nerve X?
Vagus nerve
What is the pathway of cranial nerve X? (4)
- Medulla
- Carotid sheath
- Travels inferior to base of neck
- Through thorax and oesophageal hiatus into abdomen
Where are the nuclei of cranial nerve X?
Medulla
What is the exit point of cranial nerve X?
Jugular foramen
What is the function of cranial nerve X?
- Motor: smooth muscle of pharynx, larynx and GIT
- Sensory: external ear, larynx, pharynx, viscera, taste from epiglottis of tongue
What is cranial nerve XI?
Spinal accessory nerve
Where are the nuclei of cranial nerve XI?
Superior spinal cord
What is the exit point of cranial nerve XI?
Jugular foramen
What is the function of cranial nerve XI?
Motor - trapezius, sternocleidomastoid and viscera
What is cranial nerve XII?
Hypoglossal nerve
What is the pathway of cranial nerve XII?
Passes along posterior cranial fossa within the subarachnoid space
What is the exit point of cranial nerve XII?
Hypoglossal canal
What is the function of cranial nerve XII?
Motor - intrinsic and extrinsic tongue muscles
Where are the nuclei for cranial nerve VII?
Medulla
Which cranial nerves go through the optic canal?
III optic nerve
Which cranial nerves go through the superior orbital fissure?
- III oculomotor nerve
- IV trochlear nerve
- VI abducens nerve
- Ophthalmic division of V trigeminal
Which cranial nerves go through the internal acoustic meatus?
- VII facial nerve
- VIII vestibulocochlear nerve
Which cranial nerves go through the jugular foramen?
- IX glossopharyngeal nerve
- X vagus nerve
- XI accessory nerve