Cranial Nerves and Cranial Autonomics Flashcards
Mnemonic for Cranial Nerves:
Oh - Olfactory (CN I) Once - Optic (CN II) One - Oculomotor (CN III) Takes - Trochlear (CN IV) The - Trigeminal (CN V) Anatomy - Abducens (CN VI) Final - Facial (CN VII) Very - Vestibulocochlear (CN VIII) Good - Glossopharyngeal (CN IX) Vacations - Vagus (CN X) Are - Accessory (CN XI) Heavenly - Hypoglossal (CN XII)
What cranial nerve exits the Cribriform plate?
CN I (Olfactory N.)
What cranial nerve exits the optic canal?
CN II (Optic N.)
What cranial nerve exits the superior orbital fissure?
CN III, IV, V1 branch of the trigeminal nerve and CN VI (Oculomotor, Trochlear, V1 branch, Abducens N.)»_space;> going to the eye
What cranial nerve exits the foramen rotundum?
V2 branch of the trigeminal nerve
What exits the foramen ovale?
V3 branch of the trigeminal nerve
What exits the internal auditory meatus?
CN VII and VIIII (Facial, Vestibulocochlear)
What exits the jugular foramen?
CN IX, X, XI (Glossopharyngeal, Vagus, Accessory)
What exits the foramen magnum?
CN XI (Accessory)
What exits the hypoglossal canal?
CN XII (Hypoglossal N.)
What are the functions of CN I, II and III
I - Olfactory N. - smell
II - Optic N. - vision
III - Oculomotor N. - All eye muscles except the superior, oblique, lateral rectus
What are the functions of CN IV, V, VI?
IV - Trochlear N. - superior oblique muscle (an EOM)
V - Mastication (chewing) and facial sensation
VI - Lateral rectus (an EOM)
What are the functions of CN VII, VIII and IX?
VII - Facial N - Facial movement and taste in anterior 2/3 of tongue
VIII - Vestibulocochlear N - hearing and balance
IX - Glossopharyngeal N. - Salivation, swallowing, cardiopulm
What are the functions of CN X, XI, XII?
X - Vagus N. - gut motor, swallowing, cardiopulm
XI - Accessory N. - head turn
XII - Hypoglossal N. - tongue movement
Significance of the branchial (pharyngeal) arches:
Develops into most of the structures of the face
Arch innervations 1st 2nd 3rd 4th and 6th
Trigeminal nerve
Facial
Glossopharyngeal
Superior laryngeal and recurrent laryngeal branch of vagus
First three (preotic) somites are associated with …
CN III, IV, VI
Last three (Postotic) somites are associated with
CN IX
All sympathetic fibers arise from?
What is the only named sympathetic post ganglionic nerve?
Cervical ganglion of the sympathetic trunk (already synapsed here) and jump on to blood vessels to get to their place of innervation
Deep Petrosal nerve is the only named postganglionic sympathetic nerve
Preganglionic parasympathetic fibers arise from …
Carried by which CNs?
- nuclei in the brainstem and synapse at 4 ganglia in the head (cilliary pterygopalatine, otic and submandibular)
- III, VII, IX, X
All post ganglionic fibers travel on?
branch of CN V that arrive at the structure they innervate
CN V is the highway
Olfactory N
Course: originates in the nasal cavity > through the cribiform plate > synapse in olfactory bulbs
Lesion: can’t smell
Optic N:
Course: Originates in the retina and terminates in the visual cortex
Optic chiasm = crossing over, lesions at different parts of the tract cause different vision patterns, and you can tell where the lesions are
Lesion: Anopesia (visual defects)
Ocular muscle nerves:
CN III, IV, VI
*Oculomotor:
Course: Oculomotor and Edinger Westphal nuclei
Provides innervation to most of the eye muscles, mostly raising eye and turning it inward
Lesion: Ptosis (eyelid droop), EOM paralysis, strabismus (eyes not parallel), diplopia, difficulty focusing
*Trochlear N.
Course: trochlear nucleus > through the superior orbital fissure to the superior oblique muscle
Supplies the superior oblique muscle, basically moving the eye down
Lesion: superior oblique paralysis, leading to strabismus (deviated eyes), diplopia
*Abducens N.
Course: Pontine/abducens nucleus in the pons > superior orbital fissure to lateral rectus muscle, basically moving the eye laterally
Abducts the eye
Lesion: paralysis of lateral rectus, no abudction/lateral eye movement
Right oculomotor nerve palsy
Cause
Clinical
Paralysis of the right oculomotor n.
Can’t gaze up and in, so gaze is down and out. Dilated pupil
Left abducent nerve palsy:
Cause
Clinical
Abducent nerve paralysis.
Can’t move eye laterally, so gaze is stuck medially
Trigeminal Nerve overall functions
Muscles of mastication, tensors, mylohyoid and anterior belly of the digastric
Sensory of most of the face and scalp (all over the place, not just the skin)
Trigeminal Nerve:
Course: From pons > branches in v1, v2, v3 > through the respective foramina and terminal innervations
Lesions: Trigeminal neuralgia = intense pulsating pain lasting for minutes to hours
Shingles and trigeminal nerve
Virus can follow the CN V tracts. Tingling and rash following the innervation maps of the branches
Facial N.
Course:
Nuclei within the pons > internal acoustic meatus > branches into 5
Lesion: decreased tearing and salivation, loss of taste at anterior 2/3, Bell’s Palsy (paralyzed facial muscles, eyelid drop, sagging of mouth)
*Describe the visceral motor (parasympathetic pathway) to the lacrimal gland:
Greater petrosal N. (from CN VII) > through middle cranial fossa > joins the Deep petrosal N. (sympathetic) = nerve of pterygoid canal > through the pterygopalatine fossa > parasympathetic fibers synapse to pterygopalatine ganglion > post synaptic parasympathetic fibers innervate the lacrimal gland via zygomatic branch and lacrimal nerve
*Describe the visceral motor (parasympathetic pathway) to the submandibular and sublingual glands
CN VII > chorda tympani > petrotympanic fissure > joins lingual N. (CN V3) in infratemporal fossa > parasympathetic fibers synapse in submandibular ganglion > post synaptic fibers follow arteries to glands and synapse there
Vestibulocochlear N.
Course: Vestibular branch originates at vestibule of inner ear while cochlear branch originates in cochlea of inner ear > internal auditory meatus
Lesion: loss of balance, n,v and dizziness for vestibular branch, loss of hearing for the cochlear branch
Glossopharyngeal N.
Taste and sensory in posterior 1/3 of tongue, chemoreceptor fibers to the carotid bodies, innervates stylopharyngeus m. (pharynx muscle) and parotid salivary gland (parasympathetic)
Lesion: reduced salivary secretion, loss of taste sensations in posterior tongue
*Describe the parasympathetic innervation of the parotid gland through CN IX
CN IX > tympanic N. > jugular foramen > enters middle ear > forms the tympanic plexus > Lesser petrosal nerve arises from the tympanic plexus > lesser petrosal nerve enters the middle cranial fossa > leaves cranium through the foramen ovale > parasympathetic fibers synapse at otic ganglion > postsynaptic fibers innervate parotid gland via auriculotemporal n.
Vagus N.
Parasympathetic: innervates visceral smooth muscle, cardiac muscle, glands of heart, throat and abdomen
Motor: pharynx and larynx muscles
Visceral sensory : throat, heart, lungs, abdomen organs
General sensory: external auditory canal, eardrum and pharynx
Lesion in Vagus causes….
Larynx problems, difficulty swallowing or impaired GI mobility
Spinal Accessory N.
Innervates SCM and trapezius
Lesion: paralysis of trapezius and SCM, causing difficulty elevating shoulder (traps) or turning head opposite side (SCM)
Hypoglossal N:
Intrinsic and extrinsic tongue muscles
Lesion: swallowing and speech difficulties due to impaired tongue movement. One sided lesion causes deviation of tongue to side of damage
Which nerves are SSA (special sensory Afferent modalities)
II, VIII
Which nerves are SVE (Special Visceral Afferent, Branchial)
V, VII, IX, X
Which nerves are SVA (Special Visceral Afferent) ?
I, VII, IX, X
Which nerves are GSA (General Sensory Afferent)?
V, VII, IX, X
Which nerves are GVE (General Visceral Efferent)?
III, VII, IX, X
Which nerves are GVA (General Visceral Afferent) ?
VII, IX, X
Which nerves are General Sensory Efferent)?
III, IV, VI, XI, XII
