Peripheral organisation of cranial nerves Flashcards
Name cranial nerve I
Olfactory nerve
Where in CNI derived from?
The olfactory bulb, which sits just under the frontal cortex over the frontal bone and ethmoid bone
Function of CN I?
Sensory for smell
Name CN II
Optic nerve
What foramen does CN I pass through?
Olfactory foramen
What is the optic canal a foramen for?
Optic nerve and ophthalmic artery
What passes through the superior orbital fissure?
Cranial nerves III,IV, VI and the first part of V
Ophthalmic vein
Where do the extraocular eye muscles attach?
The outside of the eye
What are the 6 extraocular eye muscles?
4 rectus muscles: superior, inferior, medial and lateral
2 oblique muscles: superior and inferior
Where do the four rectus muscles originate and attach?
Originate from common tendinous ring and attach to the sclera, anterior to the equator of the eye
Describe the passage and attachment of the superior oblique muscle
Travels up the medial side of eye and goes to trochlea which is a pulley. Goes through pulley to insert in sclera posterior to equator
Where does the inferior oblique muscle emerge from and insert into?
Emerges from maxilla inserts into sclera posterior to equator of the eye
What is the name of CN III?
Occulomotor
Which two muscles does the occulomotor nerve NOT supply
Superior oblique and lateral rectus
What cranial nerves supply superior oblique and lateral rectus?
Superior oblique= IV
Lateral rectus= VI
Where do oculomotor parasympathetic fibres supply?
Pupil/ intrinsic muscles of the eye
Oculomotor parasympathetic fibres travel to ciliary ganglion
What is the action of medial rectus?
Adducts (turns eye in)
What is the action of lateral rectus?
Abduct (turns eye out)
What is the action of superior rectus?
Elevation and adduction
What is the action of inferior rectus?
Depression
What is the action of superior oblique
Intorts
What is the action of inferior oblique
Extorts
Which muscles aid superior rectus in adduction and elevation
Inferior oblique and medial rectus
What would you see in oculomotor nerve palsy?
The only muscle that still has tone is superior oblique and lateral rectus. Eye will be down and out. Also constant dilation due to unopposed sympathetic innervation
What would you see in trochlea nerve palsy?
Paralyses the superior oblique. Right eye is up and in. Patients attempt to minimise this by tilting head so could complain of neck pain.
What would you see in abducens palsy?
Loss of ability to abduct eye. Paralysis of lateral rectus.
What is the name of CN V?
Trigeminal nerve
What are the three divisions of the trigeminal nerve?
Ophthalmic, maxillary, mandibular
What does CN V supply (generally)
Sensory nerve of the face. Supplies skin and deeper structure such as mucous membrane and anterior 2/3 of the tongue
What does the ophthalmic nerve branch into?
Lacrimal, frontal and nasociliary
What does lacrimal nerve supply?
Lacrimal glands
What does the frontal nerve supply?
Forehead
Is the maxillary sensory, motor or mixed?
Sensory
What do the branches of maxillary nerve supply?
Superior alveolar branches go to superior dentition
Infraorbital opens up onto face via infraorbital foramen
Palatine goes to palate
What is the mandibular nerve motor to?
Muscles of mastication
What are the 2 main sensory branches of the mandibular nerve?
Inferior alveolar and lingual
What does the inferior alveolar supply?
Sensory to lower dentition
What does the lingual nerve supply?
Sensory to anterior 2/3 of the tongue
What is the name of CN VII
Facial nerve
What is the motor function of the facial nerve?
Superficial muscles of facial expression
What is the chorda tympani?
Parasympathetic branch of facial nerve, travels with 3. Special sensory related to taste on anterior 2/3 of tongue
What is the greater petrosal nerve?
Higher parasympathetic branch of facial nerve- passes through parotid but does not supply
What is the name CN IX?
Glossopharyngeal
Where does CN IX exit?
jugular foramen
Function of glossopharyngeal nerve (3)
Parasympathetic to parotid gland
Special sensory to back of tongue
Sensory to the oropharynx
What is the afferent and efferent to gag reflex
Afferent= glossopharyngeal Efferent= vagus
How does the vagus nerve run down the neck?
In the carotid sheath
Between medial carotid arteries and interal jugular veins
What is the name of CN XI?
Spinal accesory nerve
Where does CN XI emerge?
Cranium not the brain
Where do nerve rootlets of CN XI arise from?
C5-C6
How do nerve rootlets travel up to brain?
Form a nerve and ascend cranial cavity via foramen magnum. Exit through jugular foramen
What does CN XI supply?
Somatic motor fibres to accesory muscles of breathing (sternocleidomastoid and trapezius)
What is the name of CN XII?
Hypoglossal
How is the hypoglossal nerve formed?
Rootlets from the medulla. Leaves the hypoglossal canal. Joined by C1 and C2 which go into infrahyoid muscles.
