Cranial nerves Flashcards
General properties of cranial nerves
- Soft and squishy
- Carry many different types of fibres
- Pass through holes in hard bone
- They are easily compressed due to tumours, inflammation and fractures
Which kind of fibres pass through cranial nerves
Motor fibres:
- Somatic
- Visceral
Sensory:
- Visceral
- General: from skin and mucous membranes
- Special: e.g. taste, vision, hearing..
Olfactory nerve
- Cranial nerve 2
- Sensory nerve of smell
- Receptors in the epithelium of nasal cavity
- Pass through foraminifera pf the crib form plate
- Into Olfactory bulb of the anterior cranial fossa
Optic nerve
Cranial nerve 3
- Comes in through optic canal to form optic chiasm
- Nasal optic fibres cross over to form the optic tract
Clinical application to CNII
- Increase in pressure of CSF can cause Papilloedema
- damage to right optic nerve causes ipsilateral eye vision loss
- damage at optic chiasma causes loss of peripheral vision (bitemporal hemianopsia)
- Damage to right optic tract causes loss of ipsilateral nasal vision loss and contralateral peripheral/temporal vision loss (homonymous hemianopsia)
Clinical application to CN I
Fractured crib form plate can cause olfactory fibres to become damaged causing anosmia
Oculomotor nerve
Cranial nerve 3
-From midbrain through superior orbital fissure
-Visceral motor:
parasympathetic to pupil constricts pupil
parasympathetic to ciliary muscle accommodates lens
-Somatic motor
to superior, inferior and medial rectus
To the inferior oblique muscle
clinical application to CN 3
- Drooping of eyelid
- Eyeball pointing outwards and down
- No accommodation of the lens
- No pupillary reflex
Trochlear nerve anatomy and clinical appication
Cranial nerve 4
- From dorsal surface of the the midbrain through the superior oblique muscle
- somatic motor innervation to to the superior oblique muscle
-Diplopia when looking down
Abducens nerve
anatomy and clinical application
cranial nerve 6
- From pons and medulla through the superior orbital fissure
- Somatic motor innervation to lateral oculomotor muscle
-Medial deviation of eye which leads to Diplopia
Trigeminal nerve (ophthalmic )
CN V1
- From pons through to trigeminal ganglion to superior orbital fissure
- General sensory from the eyelid, scalp, mucosa of the nasal cavity and sinuses, forehead, cornea
Trigeminal nerve maxillary
CN V2
- From pons through to trigeminal ganglion through to the foramen rotunda
- general sensory from the maxilla, maxillary teeth, TMJ, Maxillary sinuses and palate
Trigeminal nerve mandibular
V3
From pons to trigeminal ganglion through to the foramen vale
-General sensory from the mandibular teeth, TMJ, Mucosa of the mouth, anterior 2/3rds of the tongue
-Somatic motor: muscles of mastication, digastric, tensor velar palatine and tensor tympani
Clinical application of trigeminal mandibular
- Trigeminal neuralgia
- Loss of sensation to the face
- Loss of cornea/sneezing reflex
- Paralysis to muscles of mastication
Facial nerve
anatomy
CN VII
From between the pons and the medulla it exits via the internal acoustic meatus, the facial canal and the stylomastoid foramen
motor somatic: to muscles of facial expression and scalp, stapedius and part of digastric
Visceral motor:to the submandibular, sublingual, lacrimal and nose and palate glands
Special sensory: anterior 2/3rd of tongue
General sensory: through external acoustic meatus
Facial nerve clinical
- easily prone to damage due to long trajectory through bone
- Bell’s palsy
Vestibulococchlear nerve anatomy
CN IX -From pons and medulla -Through internal auditory meatus -Special sensory postion/balance via semicircular canals, utricle and saccule Hearing from cochlea
Clinical vestibuloccochlear
- tinnitus
- vertigo
- nystagmus
- deafness
Glossopharangeal nerve anatomy
Cranial nerve IX
-From medulla through jugular foramen
-Special sensory: posterior 1/3rd of tongue
-Visceral sensory:
carotid body and sinus
-General sensory: cutaneos middle ear and posterior mouth cavity
-Somatic motor : To stylopharangeus: helps with swallowing
-Visceral motor: Parasympathetic to parotid gland
Glossopharangeal clinical
- Loss of gag reflex
- Loss of taste in back of mouth
- Associated with damage to cranial nerve X,XI
Vagus nerve anatomy
Cranial Nerve
- From the medulla to the jugular foramen an then to everywhere
- Special sensory: auricle and external acoustic meatus
- general sensory: from auricle and palate
- Visceral sensory : GI from pharynx to SI, heart, bronchi, trachea
- Somatic motor: pharynx to oesophagus in GI and palate
- Visceral motor: Gut, bronchi and heart
Vagus nerve clinical
Problems with pharyngeal branches lead to problems with swallowing
Problems with larangeal problems lead to problem with speaking
Accessory nerve
Cranial nerve XI
- From cranial medulla and large spinal nerve roots through the jugular foramen
- Somatic motor innervation of the striated muscles of the soft palate, pharynx, larynx, sternocleidomastoid and trapezius
Clinical
-Difficulty turning head and shrugging shoulders
Hypoglossal nerve
Cranial nerve XII
- From the medulla through the hypoglossal canal
- Somatic motor innervation of the muscles of the tongue
Clinical”:
- Damage associated with a. tonsillectomy
- Can lead to atrophy and paralysis of ipsilateral side of tongue.
nerve supply of tongue?
General sensory to the anterior 2/3rd of the tongue: lingual nerve (branch of V3)
General sensory to posterior 1/3rd: glossopharyngeal
Special sensory to anterior 2/3rd: chorda timpani of VII
Special sensory to posterior 1/3rd: CN IX
