Flashcards in Cranial nerves Deck (49)
Which 2 cranial nerves are paired extensions of the forebrain and not true cranial nerves?
Olfactory and optic nerves
Autonomic Nervous System: what are the sympathetic and parasympathetic effects on pupil size?
Parasympathetic - pupil constriction
Sympathetic - pupil dilation
Which cranial nerve lies close to the tentorium cerebelli and is therefore vulnerable to compression when there is raised intracranial pressure?
What symptom would you see and why?
You would see a blown pupil - this is because the parasympathetics are on the outside of the neurone so get compressed first
What is bitemporal hemianopia and what causes it?
Bilateral visual symptoms caused by compression of the optic chasm by pituitary tumours.
What are the 4 structures that the occulomotor nerve innervates? Which of these are voluntary and which are autonomic?
1. Ciliary muscle - autonomic
2. Sphincter pupillae muscle - autonomic
3. Levator palpabrae superioris (eyelid muscle) - voluntary
4. Extra-ocular muscles - voluntary
What is ptosis? Which cranial nerve is it a pathology of?
Eyelid dropping - due to pathology of the occulomotor nerve since it innervates levator palpabrae superioris muscle (which opens the eyelid)
Which cranial nerves are tested when you test eye movements?
III, IV and VI
Which nerve innervates the superior oblique muscle that moves the eyeball?
Trochlear nerve CN IV
Which cranial nerve has the longest intracranial course?
Trochlear nerve CN IV
Which cranial nerve supplies the sensory innervation of skin and face in a dermatomal pattern?
Trigeminal nerve CN V
What are the afferent and efferent branches of the corneal reflex?
Afferent = Va opthalmic branch of trigeminal nerve.
Efferent = facial nerve
Which branch of the trigeminal nerve passes through the cavernous sinus wall, superior orbital fissure and into the orbit?
Va opthalmic division
Which branch of the trigeminal nerve passes through the foramen rotundum and into the pterygopalatine fossa?
Vb maxillary division
Which branch of the trigeminal nerve passes through the foramen ovale and into the infratemporal fossa?
Vc mandibular division
Of the branches of the trigeminal nerve, which are general sensory and which are motor?
Opthalmic and maxillary = general sensory
Mandibular = general sensory and motor
Which cranial nerve innervates the lateral rectus muscle that moves the eye?
Abducens nerve CN VI
Which 3 cranial nerves arise at the ponto-medullary junction?
Abducens nerve, facial nerve and vestibulocochlear nerve
What are the afferent and efferent limbs of the gag reflex?
Afferent = glossopharyngeal
Efferent = vagus
Which nerves arise from the medulla? What is the common route of all of them?
IX, X, XI and XII
They all exit the base of the skull and enter into the superior part of the carotid sheath.
IX, X and XI exit via the jugular foramen with the IJV.
XII exits via the hypoglossal canal.
Only X runs the entire length of the carotid sheath as it goes down into the thorax and abdomen.
Which 2 nerves run through the internal acoustic meatus into the petrous bone?
Facial and vestibulocochlear
Which nerves has special sensory taste from the tongue?
Facial - anterior 2/3rds
Glossopharyneal - posterior 1/3rd
(General and special sensory are different).
What is presbyacusis?
Age-related hearing loss
What is an acoustic neuroma?
Benign tumours of the Schwann cells surrounding the vestibulocochlear nerve - can cause compression of the nerve leading to symptoms such as: hearing loss, tinnitus, pain, vertigo, numbness, pain or weakness down one side of face (due to trigeminal compression).
Extracranial branches of which cranial nerve have a close relationship with the parotid gland? What could this lead to if there was parotid pathology?
Extra-cranial branches of the facial nerve
Parotid pathology could therefore lead to facial nerve palsy
What structures does the glossopharyngeal nerve have general sensory from?
Middle ear and tympanic membrane
Carotid body and sinus
What is the stylopharyngeus muscle and what nerve supplies it?
Muscle that elevates the larynx and the pharynx.
Supplied by the glossopharyngeal nerve.
Which nerve supplies parasympathetics to the parotid gland?
Which salivary glands does the facial nerve supply
Submandibular and sublingual, but not parotid glands
What are the 3 branches of the facial nerve that arise in the petrous bone?
Greater petrosal nerve
Chordae tympani nerve
Nerve to stapedius
Which nerve has autonomic supply to the lacrimal glands?
What symptom would you get if there is lack of lacrimal innervation?
Facial nerve lesion can lead to dry eyes
Which of the 4 cranial nerves that arise from the medulla, doesn't pass through the jugular foramen? Where does it exit instead?
The hypoglossal nerve doesn't pass through the jugular foramen, instead it runs laterally across the posterior cranial fossa and exits through the hypoglossal canal.
Which 2 muscles does the spinal accessory nerve supply?
SCM and trapezius.
What cranial nerve is the recurrent laryngeal nerve a branch of?
The right and left recurrent laryngeal nerves turn under different structures on the left and right - what are these structures?
Right recurrent laryngeal nerve turns under right subclavian, left recurrent laryngeal nerve turns under arch of aorta.
Which is the only cranial nerve that runs the full length of the carotid sheath?
The vagus nerve (as it supplies thoracic and abdominal structures).
Which cranial nerve runs across the posterior triangle of the neck?
The spinal accessory nerve.
The hypoglossal nerve is purely motor, which structures does it supply?
All the muscles of the tongue, except for palatoglossus (innervated by the vagus nerve instead).
Which cranial nerves are associated with pharyngeal arches?
Trigeminal, facial, glossopharyngeal and vagus.
What are the afferent and efferent nerves of swallowing?
Afferent = glossopharyngeal
Efferent = vagus
Which 4 cranial nerves do pre-panglionic parasympathetic neurones hitch hike along?
III, VII, IX and X
Which cranial nerve do post-ganglionic parasympathetic neurones hitch hike along?
For each cranial nerve associated with pre-ganglionic parasympathetics, name the pre-ganglionic nucleus and the associated ganglia.
III - Edinger Westphal nucleus, ciliary ganglion
VII - superior salivary nucleus, submandibular/pterygopalatine ganglion.
IX - inferior salivary nucleus, otic ganglion.
X - dorsal motor nucleus, ganglion mostly in wall of target tissue.
Describe the pupillary light reflex.
Shine light into one eye, sensory afferents carried by optic nerve to midbrain. Connects with EDW nuclei on left and right sides, parasympathetic fibres leave EDW nuclei with CN III and pass via ciliary ganglion and reach sphincter pupillae - causes constriction of pupil in both eyes.
Which 2 branches of the facial nerve carry parasympathetic fibres? What ganglion does each one pass through.
Greater petrosal nerve is associated with pterygopalatine ganglion.
Chorda tympani nerve is associated with submandibular ganglion.
Why would you get anaesthesia on the affected side with an orbital blow out fracture?
The infraorbital nerve (branch of maxillary division of trigeminal nerve) runs through the floor of the orbit and innervates skin in a dermatomal fashion. It will be injured, causing loss of sensation.
Which 3 CN's innervate extra-ocular muscles?
CN III - all except LR6SO4.
CN VI - innervates lateral rectus.
CN IV - innervates superior oblique.
What is the typical position of the eyes in an occulomotor nerv palsy?
Down and out, with severe ptosis.
Which nerves supply general sensation from the ear?
-C2 and C3
-small contribution from facial nerve