4 - Peripheral Distribution of Cranial Nerves (I + II) Flashcards
Name the 12 cranial nerves in order
Olfactory, Optic, Oculomotor, Trochlear, Trigeminal. Abducens, Facial, Vestibular, Glossopharyngeal, Vagus, Accessory, Hypoglossal
Label the 12 cranial nerves on this diagram
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What are the three cranial nerves which innervate the extraocular muscles?
Oculomotor (III), Trochlear (IV), Abducens (VI)
What are the extraocular muscles?
Superior, inferior, lateral and medial rectus muscles
Superior and inferior oblique muscles
What is the origin of the the rectus muscles?
Common tendinous ring
Where do the rectus muscles attach?
Sclera just anterior to the equator of the eye
Where do the oblique muscles attach?
Superior oblique - Common tendinous ring to the trochlear and then inserts posterior to the equator
Inferior oblique - Medial floor of the orbit to the posterolateral surface of the eyeball
What is the action of the superior and inferior oblique?
Superior oblique - Depress the eye
Inferior oblique - Elevate the eye
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Label the diagram of the extrinsic eye muscles
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What nerve innervates the
a. Superior, inferior and medial rectus muscle? b. Lateral rectus muscle? c. Superior oblique muscle? d. Inferior oblique muscle?
What nerve innervates the a. Superior, inferior and medial rectus muscle? CN III - Oculomotor b. Lateral rectus muscle? CN VI - Abducens c. Superior oblique muscle? CN IV - Trochlear d. Inferior oblique muscle? CN III - Oculomotor
What is the function of the levator palpebrae superioris?
What nerve is it innervated by?
Where does it originate?
- To lift up the eyelid
- CN III - Oculomotor
- Common tendinous ring
Where is the lacrimal gland and its function?
Top lateral corner of the orbit and is responsible for fluid over the eye
Which nerve travels through the
- Optic Canal
- Superior Orbital Fissure
- Optic nerve
- Oculomotor, Abducens, Trochlea and V1
Label the nerves of the orbit
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Where do the oculomotor presynaptic parasympathetic fibres travel to?
Ciliary Ganglion
What does the oculomotor postsynaptic parasympathetic innervate?
Sphincter pupillae and ciliary muscle
Where do the sympathetic fibres of the oculomotor nerve pass through and innervate?
Pass through the ciliary ganglion from internal carotid plexus - innervate dilator pupillae and blood vessels of the eye
What is the primary action of each rectus and oblique muscle?
Medial rectus - Adduction
Lateral rectus - Abduction
Superior rectus and Inferior oblique - elevate the eye
Inferior rectus and Superior oblique - depress the eye
How do you test the nerves of the extraocular muscles?
Ask an individual to move their eyes up and in (superior rectus, inferior oblique and medial rectus)
If they have to abduct their eye first - medial rectus can’t be used
What are the symptoms of oculomotor palsy?
All muscles except superior oblique and lateral rectus are paralysed
Pulls eye into a down and out position
Ptosis - Eyelid semi-closed
Dilated pupil - oculomotor brings parasympathetic fibres
What are the symptoms of trochlear palsy? What would you see on a patient?
Superior oblique paralysed
Prevents abduction and depression
Eye elevates and adducts
Tilts neck - so eyes are at the same angle
Complain of neck pain or inability to walk down stairs
What are the symptoms of Abducens palsy? What would you see on a patient?
Lateral rectus paralysed
Affected eye cannot abduct
Eyes appear normal when looking forward however cannot look to the side
What are the symptoms of horner’s syndrome? What would you see on a patient?
Lack of sympathetic supply to the eye
Pinned pupil due to unopposed parasympathetic activity
Ptosis - lack of tone
What is Bell’s Palsy?
Facial muscle paralysis LMN
Cornea is at risk of drying out, muscles of upper face are bilaterally innervated by upper motor neurones
What are the contents of the Carotid sheath?
Common carotid artery
Internal carotid artery
Internal Jugular Vein
Vagus nerve
How would you test the trochlear nerve?
Shine a pen torch into one eye and check that the pupils on both sides constrict
What happens if you damage your trochlear (IV) nerve?
Paralysis of the superior oblique eye muscle
Leads to unopposed extortion in one eye
Patient’s head tilts away from the site of the legion
What are the 3 sensory branches of the trigeminal (V) nerve?
V1 - Opthalmic
V2 - Maxillary
V3 - Mandibular
What happens when you damage the trigeminal (V) nerve?
By pressure aneurysm
Paralysis in muscles of mastication
Loss of corneal reflex and sensation in face
3rd molar extraction - can damage lingual nerve - loss of sensation to the tongue and reduces saliva
- Due to loss of parasympathetic supply to the submandibular and sublingual salivary glands
What happens if you damage the hypoglossal nerve (XII)?
Paralysis to ipsilateral half of the tongue
Tongue deviates towards the side of the lesion
** Important
Fill in the table on the google docs
- The nerve type, function and where it exits the skull for all 12 cranial nerves
Check the google docs
