Cranial Nerves Flashcards
Name the first six cranial nerves in order
1) Olfactory
2) Optic
3) Oculomotor
4) Trochlear
5) Trigeminal
6) Abducens
Name cranial nerves 7 - 12
7) Facial
8) Vestibulocochlear
9) Glossopharyngeal
10) Vagus
11) Accessory
12) Hypoglossal
Name origin of the first four cranial nerves
1) Olfactory - Cerebrum
2) Optic - Diencephalon
3) Oculomotor - Midbrain
4) Trochlear - Midbrain
Name the origin of cranial nerve 5 - 8
5) Trigeminal - Pons
6) Abducens - Pons-Medulla (junction)
7) Facial - Pons-Medulla (junction)
8) Vestibulocochlear - Pons-Medulla (junction)
Name cranial nerve 9 - 12 origin
9) Glossopharyngeal - Medulla
10) Vagus - Medulla
11) Accessory - Medulla
12) Hypoglossal - Medulla
Olfactory nerve (1):
Function
Exits
- Sense of smell
- Exits via Cribiform plate of ethmoid bone
Optic Nerve (2)
Function
Exits
- Mediates vision and pupillary light reflex
- Exits via the optic canal
Oculomotor Nerve (3)
Function
Exits
- Pure motor nerve that moves the eye, constricts the pupil, accommodates and converges
- All eye muscles (Except 2 - 4/6)
- Exits via superior orbital fissure
Name the eye muscles which Oculomotor nerve (3) Innervates and muscle action
- Medial rectus muscle (Adducts and converges with opposite partner)
- Superior rectus muscle (Elevates, intorts, & adducts)
- Inferior rectus muscle (depresses, extorts, Adducts)
- Inferior oblique muscle (elevates, extorts, abducts)
Also: Levator palpebrae muscle (Elevates upper eye lid)
Trochlear nerve 4
Function
Exits
- Innervates 1/6 eye muscles
- Superior oblique muscle (depresses, intorts, abducts)
Exits via: Superior orbital fissure
Trigeminal nerve
Function
Exits
Innervates muscles of mastication
(Masseter, pterygoids, temporalis)
Exits via:
- Superior Orbital fissure (opthalmic)
- Foramen rotundum (maxillary)
- Foramen ovale (mandibular)
Abducens Nerve (6)
Function
Exits
- Innervates 1/6 eye muscles
- Lateral rectus muscle (abducts eye)
- Exits via superior orbital fissure
Facial nerve (7)
Function
Exits
Innervates:
Muscles of facial expression (Buccinator, depressor labii inferioris…… no many more)
Submandibular , sublingual and lacriminal glands
Taste: (Anterior 2/3 tongue)
Skin of outer ear
EXITS: Internal acoustic meatus
Vestibulocochlear nerve (8)
Function
Exits
Innervates vestibular apparatus, cochlear
- Audition
Exits via internal acoustic meatus
Glossopharyngeal nerve (9)
Function
Exits
Function: Pharynx (stylopharyngeus muscle)
- Sensory information from skin of the external ear
- Taste from the posterior third of tongue
Exits - Jugular foramen
Vagus Nerve (10)
Function
Exits
SVE - Voluntary muscles of the pharynx, some larynx and extrinsic muscle of tongue
- Provides sensory info from skin behind ear.
Exits via the jugular foramen
Accessory nerve (11)
Function
Exits
Function - has two parts:
Cranial root - muscles of larynx and pharynx
Spinal root - Trapezius and SCM
Exits via the jugular foramen
Hypoglossal Nerve (12)
Function
Exits
- All intrinsic and most extrinsic muscles of the tongue
Exits via the Hypoglossal canal
Emerges as a series of rootlets between the pyramid and the olive
Which 6 cranial nerves are involved in swallowing?
Trigeminal (5) Facial (7) Glossopharyngeal (9) Vagus (10) Spinal Accessory (11) Hypoglossal (12)
Olfactory nerve lesion
Clinically - if the olfactory bulb is separated from the olfactory nerves or if nerves are torn - anosmia (e.g. ethmoid bone #)
Optic nerve lesions
A) monocular blindness (Across one optic tract)
B) bitemporal hemianopsia homonymous hemianopsia (optic chiasm)
quadrantanopia (Meyers loop)
macular sparing (optic radiation?)
Occulomotor lesion
As the name suggests, the oculomotor nerve supplies the majority of the muscles controlling eye movements. Thus, damage to this nerve will result in the affected individual being unable to move his or her eye normally. In addition, the nerve also supplies the upper eyelid muscle (levator palpebrae superioris) and the muscles responsible for pupil constriction (sphincter pupillae) . The limitations of eye movements resulting from the condition are generally so severe that the affected individual is unable to maintain normal alignment of their eyes when looking straight ahead, leading to strabismus and, as a consequence, double vision (diplopia).
Trochlear nerve (4)
Lesion
Interruption of CN IV paralyses the superior oblique muscle - limiting intortion?? of the eye, weakness in downward gaze, head tilting (to compensate for extortion) - affected eye rotates medially causing diplopia
Trigeminal nerve lesion
Lesion to whole nerve - • loss of general sensation from the face and mucous membranes of the oral and nasal cavities; • loss of corneal reflex (afferent limb of CN V); • flaccid paralysis (LMN type!) of muscles of mastication; • deviation of the mandible to the affected side (due to unopposed action of opposite lateral pterygoid muscles); • paralysis of tensor tympani (partial deafness)
Facial nerve lesion
Lesion:
• Flaccid paralysis of muscles supplied by CN VII • Loss of corneal reflex • Loss of taste • Hyperacusis • Bell’s Palsy • Central facial palsy / supranuclear palsy • Crocodile tears syndrome
Vestibulocochlear nerve (8)
Lesion
Signs. Unilateral sensorineural deafness, tinnitus. Slow-growing lesions seldom present with vestibular symptoms as compensation has time to occur.
Vagus nerve (10)
Lesion
Lesion:
• ipsilateral paralysis soft palate, pharynx, larynx → dysphonia, dyspnoea, dysarthria & dysphagia • loss of gag reflex (palatal reflex) • sensory loss to pharynx & larynx → unilateral loss of cough reflex • aortic aneurysms and tumours of neck & thorax → can compress CN X
Accessory nerve (11) lesion
Anatomy: motor to sternocleidomastoid and trapezius. Signs: weakness and wasting of these muscles. Causes: as ‘Vagus (X) nerve’, above.
Hypoglossal nerve (12)
Lesion
Complete hypoglossal lesion causes unilateral lingual paralysis and hemiatrophy. The protruded tongue will deviate to the paralysed side. On retraction, the paralysed side rises higher than the unaffected side.
Trigeminal Neuralgia / Tic douloureux
What is it?
Severe stabbing pain over the face
Involves the Trigeminal nerve
Most commonly felt over the areas Innervates by mandibular and maxillary divisions
- Unknown origin
