Cranial Nerves Flashcards
What nerves pass through the common tendinous ring?
SNIA
Superior branch of CN III
Nasociliary
Inferior branch of CN III
Abducens
The optic nerve is also inside but doesn’t pass through the SOF but through the optic canal
What nerves pass outside of the common tendinous ring?
Frontal
Lacrimal
Trochlear
What bone lies behind the common tendinous ring?
Sphenoid
Where does the Oculomotor Nerve Originate?
Oculomotor nucleus and Edinger-Westphal nucleus
Where does the oculomotor nerve exit?
Superior Orbital Fissure
What’s included in the superior division of CN III?
Superior Rectus and LPS
What’s the inferior division of CN III?
Medial Rectus, Inferior Rectus, Inferior Oblique
Where are the LPS and EOM nuclei of CN III?
Ipsilateral for all EOM apart from SR that’s Contralateral
LPS is central nucleus
Where does the Trochlear Nerve (CN IV) originate?
Posterior aspect of midbrain
Where does the Trochlear Nerve (CN IV) exit?
Superior Orbital Fissure & passes outside of the common tendinous ring
What is the clinical relevance of the Trochlear Nerve cause?
Vertical diplopia
What’s the longest and the shortest cranial nerve?
Trochlear - Longest
Shortest - Olfactory
Where does the Trigeminal Nerve Originate?
Anterior aspect of brainstem at pontomedually junction
Where does the Trigeminal Nerve exit?
Superior Orbital Fissure
Is Trigeminal Nerve Sensory, Motor or Mixed and how is it divided into with V1-V3?
V1 Ophthalmic Sensory
V2 Maxillary Sensory
V3 Mandibular Mixed
Within CN III where are the somatic fibres and the autonomic fibres located?
Somatic - inside the nerve
Involuntary - outside the nerve
What branches does the frontal nerve give off?
The frontal nerve is part of the ophthalmic division (V1) of the trigeminal nerve (CN IV). It gives off the supraorbital and supratrochlear branches
What branches does the nasociliary nerve give off?
The nasociliary nerve is part of the ophthalmic division (V1) of the trigeminal nerve (CN IV).
It’s name changes to the Anterior Ethmoid Nerve as it passes through the ethmoid foreamen.
It gives off the long ciliary nerves, infratrochlear nerve and posterior ethmoid nerve
What are the features of the lacrimal nerve?
Think branches
It’s the smallest of the 3 branches split into the sensory, sympathetic (comes from near the spine, no ganglionic cells, hydrates the eyes) and parasympathetic (lacrimal nucleus sending pre-gang to pteryopalatine ganglion to lacrimal gland to hydrate the eyes)
What is Hutchinson’s sign?
All of the ophthalmic nerves are linked at a terminal so if there are bubbles on the nose that don’t cross the midline then likely the eye is also involved.
Where does the maxillary division pass through?
The foramen rotundum and pterypalatine fossa
What is the infraorbital nerve?
It’s the same as the maxillary division (V2) of the trigeminal nerve (CN IV) after it passes through the inferior orbital fissure.
Where does the mandibular division (V3) pass through?
The foramen ovale
What is the function of the mandibular division (V3)?
Motor function to muscles of mastication (masseter, temporalis, medial and lateral pterygoids)
What is the origin of the abducens nerve?
Anterior aspect of the midbrain at the pontomedullary junction
The abducens nerve and what other nerve have the same origin?
The trigeminal nerve - both at the anterior aspect of the midbrain at the pontomedullary junction
Where does the abducens nerve exit?
The superior orbital fissure
What is the clinical relevance of the abducens nerve?
Palsies that lead to horizontal diplopia
Where does the facial nerve originate?
At the pons; 2 roots being sensory and motor
Where does the facial nerve exit?
At the stylomastoid foramen
Where are the 4 functions of the facial nerve?
Motor
Sensory
Special Sensory
Parasympathetic
What does the motor function of the facial nerve (CN VII) consist of?
For the muscles of expression, the posterior belly of the digastric, the stylohyoid and the stapedius muscles
What is the sensory area of the facial nerve (CN VII)?
Small area around the concha of the outer ear
What is the special sensory area of the facial nerve’s (CN III) function?
For special taste sensation to the anterior 2/3rds of the tongue via the chorda tympani
What is the parasympathetic function of the facial nerve (CN VII)?
Head and neck glands
What is ‘to zanziba by motor car’ referring to?
The facial nerve branches; temporal branch, zygomatic branch, buccal branch, marginal mandibular branches and cervical branch
TZB = Lacrimal
Buccal = should be able to keep air in the cheeks when pressing on the,
If able to open the eyes when someone is squeezing them shut = temporal, zygomatic or buccal branch issue
What is the function of the vestibulocochlear nerve?
Hearing & Balance
What is the origin of the vestibulocochlear (CN VIII) nerve?
Pons & Medulla
Where does the vestibulocochlear nerve exit?
At the internal acoustic meatus
What is the origin of the Glossopharyngeal nerve (CN IX)?
Medulla
Where does the Glossopharyngeal nerve exit?
At the jugular foramen
What is the clinical relevance of the Glossopharyngeal nerve?
Gag reflex
How many functions does the glossopharyngeal nerve (CN IX) have and what are they?
It has 4 functions - motor, sensory, special sensory and parasympathetic
What is the motor function of the Glossopharyngeal nerve (CN IX)?
Innervates the stylopharyngeus muscle of the pharynx
What is the sensory function of the Glossopharyngeal nerve (CN IX)?
Innervates the oropharynx, carotid body and sinus, posterior 1/3rd of the tongue, middle ear cavity and the eustachian tube
What is the special sensory function of the Glossopharyngeal nerve (CN IX)?
Taste to the posterior 1/3rd of the tongue
What is the parasympathetic function of the Glossopharyngeal nerve (CN IX)?
Innervation to the parotid gland
What is the origin of the vagus nerve (CN X)?
Medulla
What is the exit of the vagus nerve (CN X)?
Jugular Foramen
What is the clinical relevance of the vagus nerve?
Has so many! Heart rate, GI tract, voice
Has the longest course of all the cranial nerves
What are the 4 functions of the vagus nerve?
Motor, sensory, special sensory and parasympathetic
What is the motor function of the vagus nerve?
Innervation to the majority of the pharynx muscles, soft palate and larynx
What is the sensory function of the vagus nerve?
Innervates the skin around the external acoustic meatus and internal surfaces of the laryngopharynx and larynx
It provides visceral sensation to heart and abdominal viscera
What is the special sensory function of the vagus nerve?
Provides taste sensation to the epiglottis and root of the tongue
What is the parasympathetic function of the vagus nerve?
Innervates the smooth muscle of the trachea, bronchi, GI tract and regulates heart rhythm
What is the origin of the [Spinal] Accessory Nerve (CN XI)?
Medulla & Spine
Where does the [spinal] accessory nerve (CN XI) exit?
Jugular foramen
What is the function of the spinal accessory nerve?
Motor function to the SCM and terapzeius
What is the clinical relevance of the spinal accessory nerve?
Damage can lead to muscle wasting. Can test by getting someone to hold their shoulder up whilst you press down on them.
What is the origin of the hypoglossal nerve (CN XII)?
Medulla
What is the exit of the hypoglossal nerve (CN XII)?
Hypoglossal canal
What is the function of the hypoglossal nerve (CN XII)?
Motor function - innervating all intrinsic and extrinsic muscles of the tongue (except the palatoglossus)
What’s the clinical relevance of the hypoglossal nerve (CN XII)?
It’s uncommon but would be seen by a deviation of the tongue toward the lesion
How to tell if someone has a facial nerve palsy opposed to a stroke?
Whistle or purse lips = issues or asymmetrical smile when smiling wide. Can tell it is not a stroke as a stroke spares the forehead.