Cranial Nerves Flashcards
What CN are above the pons?
In the pons?
In the medulla?
What CN nuclei are medial?
I, II, III, IV
V, VI, VII, VIII
IX, X, XI, XII
III, IV, VI, XII
What CN is the olfactory N?
Fx?
What is the pathway of the olfactory N?
Where does it synapse?
What is an injury of the olfactory N called and how can it be damaged?
Do its afferent fibers go to the thalamus?
CN I; sensory
Smell (special sensory)
Cribriform plate of the ethmoid bone
Olfactory bulb -> piriform cortex
Anosmia; trauma, skull fracture infections, tumors
No
What CN is the optic N?
Fx?
What is the pathway of the optic N?
Arises from what?
CN II; sensory
Sight (special sensory)
Optic canal of sphenoid bone
Diencephalon
What are the three cranial nerves that innervate the ocular muscles?
What hole do these three nerves travel through?
Oculomotor N (CN III)
Trochlear N (CN IV)
Abducent N (CN VI)
Superior orbital fissure
Name the muscle with the somatic motor (efferent fiber) fx of the eye:
Moves eye up
Moves eye medial
Moves eye inferior
Moves eye superior rotation
Elevates eyelid
These fx are innervated by the _____. What CN is this?
Superior rectus m
Medial rectus m
Inferior rectus m
Inferior oblique m
Levator palpebrae
Nucleus of oculomotor N; CN III; motor
The ____ nucleus is responsible for the parasympathetic motor (visceral efferent) innervation of the oculomotor nerve. What are its two fx?
Visceral oculomotor nucleus
Sphincter pupillae -> pupillary constriction
Ciliary M -> near vision
In oculomotor N (CN III) palsy causes a ____ and ____ gaze, ____ pupil, and eyelid has to be ____ due to ptosis.
Downward and outward; dilated; manually elevated
What CN is the trochlear N?
What is its fx?
What muscle does it innervate and what is the fx of this muscle?
What does trochlear N palsy cause?
CN IV; motor
Eye movement (somatic motor)
Superior oblique m; turned eye down/in (read/stairs)
Strabismus (crossed eye), diplopia (double vision), eye tilted outward, unable to look down/in therefore the head is tilted away from the affected side to compensate
What CN is the abducens?
What is the fx?
And what muscle does it innervate?
What does abducens palsy cause?
CN VI; motor
Eye movement (somatic motor)
Lateral rectus m
Diplopia, can’t laterally move (look out) of affected eye
What CN is the trigeminal N?
What are the three divisions and what ganglion do they arise from?
What is the sensory fx and what division?
What is the motor fx and what division?
What reflex is the trigeminal N a part of and what division supplies this sensory input?
CN V; both sensory and motor
Ophthalmic (V1), maxillary (V2), mandibular (V3); trigeminal ganglion
Touch/pain/temperature to face -> V1, V2, V3
Muscles of mastication -> V3
Corneal reflex; V1
The ophthalmic (V1) division of the trigeminal N has what four branches?
What are smaller branches off two of the original branches?
Lacrimal
Frontal: supratrochlear, supraorbital N from frontal air sinus
Nasociliary: long and short ciliary, infratrochlear, ethmoidal (anterior with internal and external nasal), posterior
Meningeal branch: from tentorium cerebelli
What openings do the branches of the maxillary (V2) division of the trigeminal nerve enter and exit?
What are the six branches of the maxillary division?
Enter through foramen rotundum and exit through infraorbital foramen into maxillary region
Zygomatic: zygomaticotemporal, zygomaticofacial
Infraorbital: external nasal, superior labial
Superior alveolar: anterior, middle, posterior
Nasociliary
Palatine: orbital, greater and lesser palatine, posterior superior nasal, pharyngeal
Meningeal: anterior cranial fossa, middle cranial fossa
What are the sensory branches of the mandibular (V3) division of the trigeminal N?
Motor branches?
Buccal Lingual Inferior alveolar Auriculotemporal Meningeal
Medial ptergoid Lateral pterygoid Masseteric Deep temporal Mylohyoid
What does trigeminal palsy cause?
What are the symptoms of trigeminal neuralgia?
Numb face (sensory), weak jaw (motor) -> deviates to AFFECTED side (unopposed action of normal side)
Recurrent sudden sharp pain, tic douloureux (painful tic), wincing
What nerves induces the corneal reflex?
Input of senses by ____ nerve, transmitted to ____ nerve causing ____.
V1 of CN V
VII (bilaterally)
Eyes to blink
What CN is the facial N?
What is its fx?
What does it innervate?
CN VII; both sensory and motor
Motor, sensory
Muscles of facial expression, taste (anterior 2/3 tongue), salivation (all salivary glands except parotid), lacrimation, ear muscle (stapedius)
What are six branches of the facial N?
Posterior auricular N
Temporal N
Zygomatic N
Buccal N
Mandibular N
Cervical N
What is facial nerve dual innervation?
Upper face receives innervation form ____ sides of brain.
Lower face receives innervation from the _____ side of the brain.
Both
Opposite
Stroke on L brain, R upper face muscles work (innervation from both sides of brain), R lower face muscles do not work (innervation from opposite side of brain).
Problem with R facial nerve, R upper and lower face muscles don’t work (Bell’s Palsy).
Facial palsy is loss of the ____ reflex (motor output).
Loss of taste on _____ part of tongue.
Hyperacusis (stapedius paralysis) in which pt cannot tolerate _____.
Corneal
Anterior 2/3
Sounds
What is Bell’s Palsy?
What nerve is injured and what does it cause?
Idiopathic mononeuropathy of CN VII
Sudden onset of facial paralysis (eye and mouth)
Usually resolves in weeks to months
What CN is the vestibulocochlear N?
Fx?
What are its two parts and their fx? What does a lesion in the individual parts cause?
CN VIII; sensory
Hearing, balance, equilibrium
Chochelar: hearing; lesion causes loss of hearing, tinnitus
Vestibular: equilibrium, compensatory eye movement; lesions cause vertigo, nystagmus, vomiting, nausea
What CN is the glossopharyngeal?
Fx?
What muscle does it innervate?
CN IX; both sensory and motor
Motor and sensory: taste/sensation on posterior 1/3 of tongue, salivation (parotid gland), carotid body and sinus (chemo/baroreceptor)
Stylopharyngeus m: elevates pharynx for swallowing/gagging
Glossopharyngeal N palsy causes loss of what?
What are the hemodynamics effects?
Loss of gag reflex, taste on posterior 1/3 of tongue, sensation of upper pharynx
Innervates carotid sinus -> loss of CN IX tricks body into thinking there is low BP -> body responds by increasing BP through vasoconstriction -> increases BP
What CN is the vagus N?
Fx?
What is the autonomic fx?
CN X; both sensory and motor
Motor and sensory: taste in supra-epiglottic region; swallowing (genioglossus m); elevates palate; midline uvula; talking (muscles of speech); coughing
Parasympathetic innervation to the thoracoabdominal visceral smooth muscle; acts as a chemo/baroreceptor in the aortic arch
What are the vagal nuclei and what CN do they innervate?
Nucleus solitarius: VII, IX, X
Nucleus ambiguus: IX, X, XI
Dorsal motor nucleus: X
What is the fx of the three vagal nuclei?
Nucleus solitarius: visceral sensory info (taste, baroreceptors, gut distention)
Nucleus ambiguus: motor innervation of pharynx, larynx, upper esophagus (swallowing, palate elevation)
Dorsal motor nucleus: sends autonomic fibers to heart, lungs, upper GI
What are five symptoms of vagus N palsy?
What are the hemodynamics effects?
Hoarseness, dysphasia, dysarthria
Loss of gag reflex
Loss of sensation of pharynx and larynx
Weak side of palate collapse (lower)
Uvula deviates AWAY from affected side
Unopposed sympathetic stimulation of heart -> increase HR
What is the most common cause of syncope?
This is caused by trigger to the ____ nerve -> increases parasympathetic outflow -> _____ HR, decrease BP -> faint
Caused by what?
Vasovagal syncope
Vagus N; decreases
Hot weather, prolonged standing, pain, sight of blood
What CN is the accessory N?
What is its fx?
What opening does this nerve travel through?
What does accessory N palsy cause?
CN XI; motor
Motor: turns head to opposite side; innervates SCM and trapezius
Jugular foramen
Difficulty turning head to the unaffected side (SCM), shoulder droops on affected side
What CN is the hypoglossal N?
Fx?
What opening does it exit from?
Palsy of this nerve causes what?
CN XII; motor
Motor: tongue movement; innervate all tongue muscles except genioglossus/palatoglossus m (CN X)
Hypoglossal canal
Protrusion of tongue TOWARD affected side because opposite side pushes tongue away unopposed
Describe the innervation of the tongue:
Motor
Taste
General sensory
What separates anterior 2/3 of tongue from posterior 1/3?
MOTOR
Hypoglossal N; vagus N innervate palatoglossus m
TASTE
Anterior 2/3: CN VII
Posterior 1/3: CN IX
Tongue root, larynx, upper esophagus: CN X
SENSORY
Anterior 2/3: CN V3
Posterior 1/3: CN IX
Tongue root: CN X
Terminal sulcus
What are the five cranial nerve reflexes?
What nerve senses these reflexes and what nerve causes the action of the reflex?
Does a damaged V1 affect the lacrimation reflex?
Corneal: sensed by V1 of CN V -> output CN VII (blinking)
Lacrimation: sensed by V1 -> output CN VII (tearing)
Gag: sensed by CN IX -> output by CN X (gaging)
Jaw jerk: sensed by V3 of CN V -> output by V3 (trigeminal reflex)
Pupillary: sensed by CN II -> output by CN III (constrict pupil)
Damaged V1: no reflex tears, but still can have emotional tears
The only ocular muscles not innervate by the CN III are _____ innervated by CN IV and ______ innervated by CN VI.
Superior oblique
Lateral rectus
Name the nerves/structures that go through each opening in the skull:
- Cribriform plate
- Optic canal
- Superior orbital tissue
- Foramen rotundum
- Foramen ovale
- Foramen spinosum
- Internal auditory meatus
- Jugular foramen
- Hypoglossal canal
- Foramen magnum
- CN I
- CN II, ophthalmic A
- CN III, IV, VI, V1
- CN V2
- CN V3
- Middle meningeal A
- CN VII, VIII
- CN IX, X, XI, jugular vein
- CN XII
- Brainstem, spinal root of CN XI, vertebral A
