Cranial Nerves Flashcards
Which cranial nerve innervates muscles derived from the first pharyngeal arch?
Trigeminal (V3- Mandibular)
Which cranial nerve innervates muscles derived from the second pharyngeal arch?
Facial (CN VII)
Which cranial nerve innervates muscles derived from the third pharyngeal arch?
Glossopharyngeal (CN IX)
Which cranial nerve innervates muscles derived from the fourth pharyngeal arch?
Sup laryngeal branch of vagus (CN X)
Which cranial nerve innervates muscles derived from the sixth pharyngeal arch?
Recurrent laryngeal branch of vagus (CN X)
Which pharyngeal arch never develops?
5th
Where does CN I enter the skull?
Foreamina of the Cribiform plate in ethmoid bone
What is the embryological origin of CN I?
Embryonic nasal placode
What nuclei are associated with CN I?
Olfactory bulbs (ant cranial fossa)
What is olfactory mucosa?
Made of olfactory epithelium and underlying lamina propria (connective tissue with BV’s). The mucus protects epithelium and allows odours to dissolve for detection
What is the origin of CN II?
Ganglion cells in retina
Where does CN II exit the skull?
Through optic canal (into middle cranial fossa)
Describe the course of CN II
Ganglion cells > optic canal > optic chiasm > optic tract > LGN > visual cortex
Where is the termination of CN II?
Lateral geniculate nucleus (in thalamus)
What tests can be done to test CN II?
Visual acuity (Snellen) Assess visual fields (Move wagging finger) Asses pupillary light reflex- both should constrict when one eye stimulated
What are the efferent muscles supplied by CN III?
Med/ Sup/ Inf Rectus
Inf oblique
Levator palpebrae superioris
What autonomic supply is provided by CN III?
Sphincter pupillae
Cilliary muscles
(Both PNS- Ciliary ganglion)
Where does CN III originate?
Ant surface brainstem (between mid brain and pons)
What nuclei are associated with CN III?
Occulomotor nucleus
Eidinger-westphal nucleus
Where does CN III exit the skull?
Superior orbital fissue
What are the two divisions of CN III, where do they split?
Superior: Sup rectus and LPS
Inferior: Med/ inf rectus + inf oblique + ciliary muscles + sphincter pupillae
What is the course of CN III?
From midbrain, along lateral wall of cavernosus sinus, into orbit through SOF (then splits into sup and inf divisions)
How do you test CN III?
Draw H with finger, check P can follow Check accommodation (pupils constrict) Test pupil constriction
What is controlled by CN IV?
Superior oblique muscle
Where does CN IV originate?
From post brainstem (just below inf colliculus)
ONLY CN TO EMERGE POST
Where does CN IV leave the skull?
Sup orbital fissure
What nucleus is associated with CN IV?
Trochlear
How do you test CN IV?
Ask P to look out and down
Ask if experiencing diplopia
What is the course of CN IV?
Passes round to ant brainstem, goes along inf surface of tentorium cerebeli (seperates cerebellum and occipital lobe), then along lateral wall of cavernous sinus
What are the afferent components of CN V?
Sensory from face, mouth, nasal cavity, dura mater, part of EAM
Sensation (not taste) from ant 2/3 tongue
What are the efferent components of CN V?
Mastication (temporalis, massester, med/ lat pterygoid)
Tensory tympani and tensor veli palatini
Ant belly diagastric
Mylohyoid
What are the autonomic components of CN V?
Lacrimal gland (from opthalmic V1 branch)
Where does CN V originate?
From ant/ lat surface of pons
Large sensory root, small motor root
What are the three branches of CN V?
VI- Opthalmic (sensory)
V2- Maxillry (sensory)
V3- Mandibular (sensory and motor)
Where do each of the CN V branches exit the skull?
V1- Opthalmic (Sup orbital fissure)
V2- Maxillary (Foreamen rotundum)
V3- Mandibular (Foreamen ovale)
What ganglion is associated with CN V?
Trigeminal ganglion in trigeminal depression (petrous part of temporal bone)
What tests could be done for CN V?
Test sensation in all three (V1/2/3) areas of the face
Test muscles of mastication
What are the three branches of the opthalmic (V1) nerve?
Frontal- skin of forehead/ upper eyelid/ frontal sinus
Lacrimal- to lacrimal gland
Nasociliary- Ciliary muscles and cornea
(ALL SENSORY)
What is supplied by CN VI?
Lateral rectus
What is the origin and nucleus of CN VI?
Ant brain stem at pontomedullary junction
Abducens nucleus
Where does CN VI exit the skull?
Superior orbital fissure
What tests could be done for CN VI?
Test lateral gaze
Ask if P experienced diplopia
What is the course of CN VI?
From ant brainstem, pierces dura covering the clivus, travels up in dural canal, crosses petrous temporal bone and cavernosus sinus into SOF
What is the afferent component of CN VII?
Taste from ant 2/3 tongue
Sensation from posterior external ear
What is the efferent component of CN VII?
Muscles of face
Stapedis, post belly diagastric and stylohyoid
What are the autonomic components of CN VII?
PNS to lacriaml gland, submandibular and sublingual glands, mucous membranes of nasal cavity and hard + soft palate
Where is the origin of CN VII?
Lateral brainstem at pontomedullary junction
What nuclei are associated with CN VII?
Facial motor
Trigeminal (for general sensation)
Solitary nucleus (for taste sensation)
What is the course of CN VII?
Internal acoustic meatus, enlarges into the geniculate ganglion, splits into it’s branches in the parotid gland and leaves skull through stylomastoid foreamen
How could you test CN VII?
Taste on ant 2/3 tongue
Saliva and tear production
Facial expression (raise eyebrows, scrunch eyes, blow out cheeks, purse lips, smile and show teeth)
What are the three intercranial branches of CN VII?
Greater petrosal- PNS to nasal/ palatine/ lacrimal glands
Nerve to stapedius- Motor to stapedius
Chorda tympani- Taste ant 2/3 tongue + PNS to submandibular/ sublingual glands
What are the extracranial branches of CN VII?
Temporal, zygomatic, buccal, mandibular, cervical
What are the components of CN VIII?
Balance and hearing
Where is the origin of CN VIII?
Lateral brainstem at pontomedullary junction
What is the course of CN VIII?
Crosses post cranial fossa and two divisions join in the petrous part of the temporal bone then leave skull through IAM
Where does CN VIII exit the skull?
Internal acoustic meatus
What is the embryological origin of CN VIII?
Otic placode
What nuclei are associated with CN VIII?
Vestibular- Balance
Cochlear- Hearing
What ganglia are associated with CN VIII?
Spiral (cochlear) ganglion in central axis of cochlear
What tests could be done to assess CN VIII?
Hearing test (Whisper in ear 66/99)
Weber and rinne
Walk on spot with eyes closed (vestibular)
What are the afferent components of CN IX?
Sensory from carotid, oropharynx, palatine tonsils, middle ear and pharyngotympanic tube
Taste from post 1/3 of tongue
What are the efferent components of CN IX?
Stylopharyngeus muscle
Where does CN IX originate?
Several rootlets on ant/ lat medulla (rootlets merge in jugular foreamen)
Where does CN IX exit the skull?
Jugular foreamen
How could you test CN IX?
Taste on post 1/3 of tongue
Test gag reflex
Ask about dry mouth (saliva production)
What are the afferent components of CN X?
Larynx/ laryngopharynx/ oesophagus/ epiglottis
Aortic chemo/ baroreceptors
Lungs/ heart/ abdo viscera
What are the efferent components of CN X?
Palatoglossus (tongue) Soft palate (except tensor veli palatini) Larynx and pharynx (except stylopharyngeus)
What are the autonomic components of CN X?
PNS to pharynx/ larynx
PNS to thoracic/ abdo viscera
Where does CN X originate?
Rootlets on ant/ lat medulla (Just inf to those of CN IX)
Where does CN X exit the skull?
Jugular foreamen
Which two branches of CN X supply areas in the pharynx?
Sup laryngeal (internal laryngeal branch)- Above vocal cords Sup laryngeal (external laryngeal branch)- Vocal chords Recurrrent laryngeal- All intrinsic larynx muscles
What is the course of the recurrent laryngeal nerve?
Split from CN X at aortic arch
L goes under arch and up
R goes straight back up
How could you test CN X?
Assess speech/ cough
Assess swallowing/ uvula deviation
Assess gag relex
Ask about heart/ GI symptoms
What is supplied by CN XI?
Sternocleidomastoid and trapezius
What is the origin of CN XI?
C1-C5
technically its a spinal accessory nerve
What is the course of CN XI?
Enters skull through foreamen magnum
Goes through post cranial fossa
Leaves skull again through jugular foreamen
What nuclei are assocaited with CN XI?
Spinal accesory nucleus
Nucleus ambiguens
What tests can be done for CN XI?
SCM- Turn head against pressure
Trapezius- Shrug shoulders against pressure
What happens to the cranial component of CN XI?
It joins the vagus nerve (CN X)
What is supplied by CN XII?
All intrinsic (sup/ inf longitudinal + transversus + verticalis) and most extrinsic (genioglossus/ styloglossus/ hyoglossus) muscles of tongue
Which is the only tongue muscle not supplied by CN XII?
Palatoglossus (done by CN X)
What is the origin of CN XII?
Rootlets on ant surface of medulla
Where does CN XII leave the skull?
Hypoglossal canal in occipital bone
What nucleus is associated with CN XII?
Hypoglosal nucleus
How can you test CN XII?
Test tongue movements
Press tongue on inside of cheek against resistance
Which nerve does taste innervation of the post 1/3 of the tongue?
Glossopharyngeal (CN IX)
Which nerve does taste innervation on the ant 2/3 of the tongue?
Facial (CN VII)
Which nerve does general sensation (not taste) from the ant 2/3 tongue?
Trigeminal (CN V)
Which nerve does general sensation from the post 1/3 tongue?
Glossopharyngeal (CN IX)
Which cranial nerves have autonomic components?
1973 (Vagus, Glossopharynheal, Facial and Occulomotor)
What pneumonic aids in remembering whether CN’s are sensory or motor?
Some say marry money but my brother says big boobs matter more
Which cranial nerve supplies the muscles of mastication?
Trigeminal (V3- Mandibular)
Which cranial nerve supplies the mylohyoid muscle?
Trigeminal (V3- Mandibular)
Which is the only branch of the trigeminal nerve with motor component?
V3- Mandibular
Which cranial nerve supplies the stapedius muscle?
Facial (CN VII)
Which cranial nerve supplies the stylohyoid muscle?
Facial (CN VII)
Which cranial nerve supplies post belly diagastric?
Facial (CN VII)
Which cranial nerve supplies the parotid gland?
Glossopharyngeal (CN IX)
PNS
Which cranial nerve supplies stylopharyngeus?
Glossopharyngeal (CN IX)
What are the autonomic components of CN IX?
PNS to parotid gland
Which cranial nerve supplies PNS innervation to the pharynx and larynx?
Vagus (CN X)
Which cranial nerve provides sensory info from the larynx?
Vagus (CN X)
Which cranial nerve supplies palatoglossus?
Vagus (CN X)
Which cranial nerve supplies all the larynx and pharynx? (Except stylopharyngeus)
Vagus (CN X)
Which cranial nerve supplies the muscles of the soft palate (except tensor veli palatini)?
Vagus (CN X)
Which cranial nerve provides sensory info from the mouth?
Trigeminal (CN V)
Which cranial nerve provides sensory info from the dura mater?
Trigeminal (CN V)
Which cranial nerve provides sensory info from the oropharynx?
Glossopharyngeal (CN IX)
Which cranial nerve provides sensory info from the middle ear and eustacian tube?
Glossopharyngeal (CN IX)
Which cranial nerve provides sensory info from the oesophagus and epiglottis?
Vagus (CN X)