Cranial Nerves Flashcards
What are the 12 cranial nerves?
- Olfactory
- Optic
- Oculomotor
- Trochlear
- Trigeminal
- Abducens
- Facial
- Vestibulocochlear
- Glossopharyngeal
- Vagus
- Spinal accessory
- Hypoglossal
What are the varieties of motor to voluntary muscle controls of the cranial nerves?
- Somatic motor
2. Branchial motor
What are some of the muscles/glands affected by motor to involuntary muscle nerve supply?
- Sphincter pupillae
- Lacrimal glands
What are the variety of sensory controls of the cranial nerves?
- From viscera e.g. lungs, bronchi
- General sensation e.g. touch, pain
- Special senses e.g. taste
What kind of nerve is the olfactory nerve?
Special sensory
Which is the only cranial nerve able to regenerate?
Olfactory nerve
What kind of epithelium is the olfactory nerve made up of?
Olfactory epithelium
What are the functions of the olfactory nerve?
- Smell from nasal mucosa of each nasal cavity, nasal septum and superior conchae
What is anosmia?
- Inability to smell
- Epithelial cells are blocked with mucous - olfactory nerve not working properly but will regenerate
What kind of nerve is the optic nerve?
Special sensory: for vision - allows you to see
What is different about the optic nerve cell endings in the retina?
They are turned upside down - nerve cells are round the wrong way in the retina
Where does the optic nerve exit?
Through the orbital/optic canal
Where does the eye get its vision from?
The retina
What condition can affect the optic nerve?
- Multiple sclerosis: causes degeneration of the nerve fibre of the eye
- Targets the optic nerve - nerve loses the myelin
What kind of nerve is the oculomotor nerve?
- Somatic motor
- Visceral motor
If the oculomotor nerve is affected what will happen to the eye on the affected side?
- Eye will go down and out
What muscles does the somatic motor part of the oculomotor nerve affect and what are their functions?
- Superior rectus: for looking up
- Medial rectus: moves eye towards the middle
- Inferior oblique: moves eyes outwards and upwards
- Levator palpebrae: holds eyelids open
What does the visceral motor part of the oculomotor do to the P/S?
P/S to sphincter pupillae (constricts eye) and ciliary muscle (allows you to look at near and far objects)
Compression of the oculomotor nerve may occur due to raised intercranial pressure. What may this be a result of?
Could be due to a number of reasons. Might be:
- Bleed
- Tumour
- Cancer etc.
What kind of nerve is the trochlear nerve?
Somatic motor: affects muscles around the eye
Where are the cell bodies of the trochlear nerve located?
In the midbrain
The trochlear nerve is a motor nerve to the superior oblique. What does this do?
Pulls eye down and out
What is diplopia in the eyes?
Double vision
- Can result in isolated palsy
What kind of nerve is the ophthalmic branch of the trigeminal nerve?
General sensory (like touch, pain and temperature)
Where do you get sensation from the ophthalmic branch of the trigeminal nerve?
- Cornea
- Skin of forehead
- Scalp
- Eyelids
- Nose
- Mucosa of nasal cavities
- Paranasal sinuses
What kind of nerve is the maxillary branch of the trigeminal nerve?
General sensory (like tough, taste and temperature)
Where do you get sensation from the maxillary branch of the trigeminal nerve?
- Face over maxilla
- Upper lip
- Maxillary teeth
- Maxillary sinuses
What kind of nerve is the mandibular branch of the trigeminal nerve?
General sensory
Where do you get sensation from the mandibular branch of the trigeminal nerve?
- Side of the mandible
- Mandibular teeth
- Mucosa of the mouth
- Anterior 2/3 of the tongue
Which nerve supplies the muscles of facial expression?
The facial nerve
Which nerve supplies the muscles of mastication?
The trigeminal nerve
What kind of nerve is the abducens nerve?
Somatic motor
Where does the abducens nerve arise from?
The pons
The abducens nerve is a motor nerve to the lateral rectus muscle. What does this do?
Moves the eye from side to side
What does the pneumonic LR6 SO4 AR3 mean?
- Lateral rectus: supplied by CN6 (abducens)
- Superior oblique: supplied by CN4 (trochlear)
- All the rest (of the eye): supplied by CN3 (oculomotor)
What is the clinical test for the facial nerve?
Tell patient what you are going to do before yo do it - then ask them to raise their eyebrows, close their eyes really tight and then puff out their cheeks
What are the 3 types of facial nerve?
- Branchial motor
- Special sensory
- Visceral motor
What does the branchial motor division of the facial nerve supply?
- Motor to muscles of facial expression, scalp and stapedius
Where is the stapedius muscle found in the body and what does it do?
- Smallest muscle in the body, found in the ear
- Purpose is to contract and protect inner ear organs by dampening the noise
- If the patient has a problem they will say that noises are louder in one ear compared tot he other ear
What does the special sensory division of the facial nerve supply?
- Taste to anterior 2/3 of the tongue and palate
Which nerve supplies taste to the anterior 2/3 of the tongue and palate?
The facial nerve
What does the visceral motor division of the facial nerve supply?
- P/S to submandibular and sublingual salivary glands, lacrimal glands and glands of the nose and palate
- Goes through, but does not supply the parotid gland
What kind of nerve is the vestibulocochlear nerve?
Special sensory
The vestibulocochlear nerve allows hearing from the spiral organ. What is this?
The inner ear
What is an internal acoustic neuroma?
- Slow growing tumours: benign and grow about 1mm per year
- Concern: to try to get the tumour have to go in behind ear, through under the skull and the brain to get to the tumour, then have to get the tumour out
- It is right beside the facial nerve and cerebellum - if have any cut of the facial nerve will result in facial paralysis
What are the different sections of the glossopharyngeal nerve?
- Somatic motor
- Visceral motor
- Visceral sensory
- Special sensory
- Somatic sensory
What is the function of the somatic motor branch of the glossopharyngeal nerve?
Motor to stylopharyngeus
What is the function of the visceral motor branch of the glossopharyngeal nerve?
P/S to parotid gland
What is the function of the visceral sensory branch of the glossopharyngeal nerve?
Parotid gland, pharynx, middle ear
What is the function of the special sensory branch of the glossopharyngeal nerve?
Taste to posterior 1/3 of tongue
What is the function of the somatic sensory branch of the glossopharyngeal nerve?
- External ear and TINY bit of sensation to inside of ear
What are the different branches of the vagus nerve?
- Somatic motor
- Visceral motor
- Visceral sensory
- Special sensory
- General sensory
What is the clinical test for the vagus nerve?
- Get patient to say ‘ahhh’: if uvula swings over to one side then there is a potential problem
- If there is a problem the patient won’t be able to swallow properly and their gag reflex may not be there
What is the function of the somatic motor branch of the vagus nerve?
- Muscles of pharynx
- Intrinsic muscles of larynx
- Muscles of palate
- Muscle in upper 2/3 of oesophagus
What is the function of the visceral motor branch of the vagus nerve?
P/S to trachea, bronchi, GIT and heart
What is the function of the visceral sensory branch of the vagus nerve?
- Tongue
- Larynx
- Respiratory tract
- Heart
- Upper GI to left colic flexure
What is the function of the special sensory branch of the vagus nerve?
Supplies taste to the epiglottis and palate
What is the function of the general sensory branch of the vagus nerve?
- Auricle
- External auditory meatus
What kind of nerve is the spinal accessory nerve?
- Somatic motor
What muscles does the spinal accessory nerve effect?
- Sternocleidomastoid (turns neck towards opposite side)
- Trapezius
What kind of nerve is the hypoglossal nerve?
Somatic motor
What is the function of the somatic motor branch of the hypoglossal nerve?
Motor to intrinsic and extrinsic muscles of tongue (EXCEPT palatoglossus)
