Cranial Nerves Flashcards
What kind of nerve is the olfactory nerve CN1 and what is its central connection.
The olfactory nerve is a special visceral afferent ( SENSORY) nerve
It’s central connection is with the olfactory bulb
Where does CN1 exit the skull?
Olfactory foramina in the cribriform plate
What is CN1 function and how do we test it
Function - Sense of smell which come form the receptors cells in the nasal mucosa
To test this - a pungent smell is applied to each nostril ( scratch and sniff cards sometimes used)
What type of nerve is the Optic nerve CN2 and what is its central connection
It is a special sensory afferent nerve and its central connection is the thalamus
Where does CN2 exit from the skull
Optic canal
What is the function of CN2 and how do we test this
Function - vision, from the retina of the eye to the brain
To test this - use a visual acuity test, ASMLER grid to record visual defects/ muscular function
Nerve CN3 is the oculomotor nerve, what kind of neuron is this and what is its central connection
CN3 is both general somatic efferent ( motor) as well as general visceral efferent ( parasympathetic motor)
It’s central connection is the midbrain
Where does CN3 exit the skull
Superior orbital fissure
Since CN3 has both motor and parasympathetic fibres what are the two functions and how can we test these?
General somatic efferent - innervates levator palpebrae, med/inf/sup rectus and inf oblique
- to test this we would use visual filed test = LID LAG
General visceral efferent - innervates sphincter pupillae and ciliary muscles for pupil contraction and accommodation
- to test this we would use direct, consensual light and accommodation relfexes
The Throchlear nerve is CN4, name the type of neuron that it is and where its central connection is
It is a general somatic efferent neuron
It’s central connection is the midbrain
Where does the trochlear nerve exit the skull
Superior orbital fissure
Which nerve functions to innervates the superior oblique muscle and how would this be tested
The Trochlear nerve CN4 and to test this use a visual field test
What are the three divisions of the trigeminal nerve, what kind of neuron is each and where do they exit the skull
Where is the central connection
The trigeminal nerve CN5 has three Diviosns
- the ophthalmic division which is a general somatic afferent neuron and exits the skull via the superior orbital fissure
- the maxillary division which is general somatic afferent nerve and it exits the skull at the foramen rotundum
- the mandibular branch is the last division and is a mixed neuron with both general somatic afferent and brachial motor, this exits the skull via the foramen ovale.
There central connection is PONS
The trigeminal nerve supplies sensations to the face and innervates the muslces of mastication, what are some ways you can test this nerve
Reaction to touch with eyes closed in each area the divisions supply
CNV1 - corneal reflex
CNV3 - jaw jerk reflex and open jaw against resistance, clench teeth together
The facial nerve CN7 contains three different types of neurones, which all have the same central connection and exit from the skull.
Name them
Special visceral afferent
General visceral efferent ( parasympathetic motor)
Special visceral efferent ( branchial motor)
The central connection is the pontomedullary junction and they exit the skull via the internal acoustic meatus > facial canal> stylomastiod foramen.
If a nerve is branchial motor what does this mean
Innervate skeletal muscle derived form brachial arches, including the muscles of mastication, facial expression and the palatal, laryngeal, trapezius and sterncleidmastiod muslces
What are the branches of the facial nerve
Frontal
Zygomatic
Buccal
Marginal Mandibular
Cervical
Posterior auricular
What are the functions of the facial nerve
Special visceral afferent - sensation from auricle and external acoustic meatus. Taste from anteior 2/3 of tongue
General visceral efferent ( parasympathetic motor) - secrete motor for submandibular and sublingual glands( via the submandibular ganglion). Innverates the lacrimal gland and nasal/oral cavity mucosal lining ( via pterygopalatine ganglion)
Special visceral efferent ( branchial Motor) - innervates muslces of facial expression, posteiror belly of diagastric and stylohyoid and stapedius
The sensory neuron of the facial nerve is rarely tested, how can you carry out tests for the other two function
General visceral efferent - assessment of dry mouth
Special visceral efferent - raise eyebrows, show teeth, blow out cheeks, close eye against resistance
The vestibulocohclear nerve is the 8th cranial nerve, it is a special somatic afferent nerve.
What is its central connection and where does it exit the skull
Central connection is the pontomedullary junction and it exits the skull via internal aucostic meatus
What is the function of CN8 ( it has two branches)and how can we test this
Vestibular branch - sensation of equilibrium and balance
- fistula test
Cochlear brach - sensation of hearing
- whispered voice test
Name some functions of the glossopharyngeal nerve
Sensory imput from the posterior one 1/3 of the tongue palatine tonsils, oropharynx, mucosa of middle ear
Taste from from the posterior 1/3 of tongue
Sensory information from carotid body
Secretomotor for parotid gland
Innervates stylopharyneus, pharyngeal constrictor. Assists in phonation and swallowing
Via what ganglion does CN9 innervate the parotid gland
Otic ganglion
What are the functions of the vagus nerve which is a mixed sensory and Motor nerve
Sensory information from larynx, auricle, external acoustic meatus and dura mater of posterior cranial fossa
Special sensory - taste from palate and epiglottis
Information from aortic body, oesphagous, lungs, bronchi, heart and intestines
Innervates thoracic and intraabdominal viscera including all smooth muscle and glands
Innervates laryngeal and pharyngeal muscles ( expect stylopharngeus)
Permits phonation and swallowing
What reflex is the vagus nerve responsible for
The gag reflex
The glossopharnygeal nerve and the vagus nerve are tested together, how is this carried out
Speech assessment for dysarthria and dysphonia
Patient says ‘ah’ to move palate and uvula
Patient puffs out cheeks with lips closed ( in dysfunction air will escape out of the nose)
Assess strength of cough, swallow test - observe of absent swallow or cough
What kind of nerve is the accessory nerve and where is the central connection and the exit from the skull
CN11 is an a general somatic efferent, its central connection is the medullar oblongata and it exits the skull via the jugular foramen
What is the function of CN11 and how do u access its function
Innervates the sternocleidmastiod and trapezius muslces and muslces of the soft palate
To test this - shrug shoulders or turn head against resistance on one side
The final cranial nerve CN12 is the hypoglossal nerve it is a general somatic efferent nerve.
Where is this nerves central connection and where does it exit the skull
It’s central connection is the medulla oblongata and the exit is the hypoglossal canal
What does the CN12 innervate and how do you test this function
Innervates all intrinsic and extrinsic muscles of the tongue .
This is tested by assessing the tongue for wasting/ deviation when push out. Say ‘’ yellow lorry’’ to assess speech
What is the one tongue muscle that isn’t innervated by the glossophrnygeal nerve and what nerve is it instead innervated by
The palatoglossal nerve is not innervated byCN9 instead by the vagus nerve
A patient comes in complain of loss of pupillary constriction what nerve would be affected here
CN2 the optic nerve
Anosmia( loss of smell) ; cerebrospinal fluid rhinorrhea is an abnormal finding from what kind of lesion
Fracture of cribriform plate which has affected CN1
A Patient comes in following laceration of the neck. What symptoms would they show and what nerve would be affected
Patient would come in complaining of drooping of shoulder
This would be from paralysis of the sternocleidomastiod and descending fibres.
The accessory nerve would have been affected
Your patient comes in complaining that their lower jaw is deviating when they open and that there is loss of pain and touch in face
What nerve has been damaged here?
The trigeminal nerve has been affected in this case
Injury to terminal branches (particularly CNV2) in the roof of the maxillary sinus ; pathological processes affecting trigeminal ganglion.
The parotid gland has been lacerated, what will the patient complain of and subsequently which nerve will have been affected?
The patient will have paralysis of the facial muscles, they will say that this eye still remains open yet they cannot wrinkle their forehead
Patient has said that their facial muscles are paralysed however they are still able to wrinkle their forehead. Explain what is happening hear with relation to cranial nerves.
The most common cause here is a intracranial hematoma ( a stroke) due to injury of the facial nerve
TEST
TET
Loss of taste on posterior third of the tongue and loss of sensation of the soft palate on the affected side.
These are symptoms which would be presented if what cranial nerve was affected
Glossopharyngeal CN9
Which foramen does the facial nerve pass
Stylomastiod foramen
Which foramen of the skull do the 3 divisions of the trigeminal nerve exit via
Ophthalmic - supra orbital fissure
Maxillary - Foramen rotundum
Mandibular - Foramen ovale
The foramen spinsosum allows passage of which artery
Middle meningeal artery
Which foramen is not present in life as it is filled with cartilage
Foramen lacerum
Which pharyngeal arch does the facial nerve embryologically come from
2nd pharyngeal arch
Muslces of facial expression
Which pharyngeal arch does the trigeminal nerve arise from
1st pharyngeal arch
