Cranial Nerves Flashcards
What type of nerve fibers convey impusles from the skin and skeletal muscle spindles?
General somatic afferents (somatic sensation aka general sensory)
[GSA]
What type of nerve fibers convey impulses from the viscera and blood vessels?
General visceral afferents (visceral sensation)
[GVA]
What type of nerve fibers innervate the smooth muscle of the viscera, intraocular mm, heart, salivary glands, etc.?
General visceral efferents (visceromotor function)
[GVE]
What type of nerve fibers innervate skeletal muscles?
General somatic efferents (somatomotor function)
[GSE]
What special type of nerve fibers conduct impulses from the retina and from the auditory and vestibular apparatus?
Special somatic afferents
What special type of nerve fibers conduct impulses from the taste buds of the tongue and from the olfactory mucosa?
Special visceral afferents (special sensory)
[SSA]
What special type of nerve fibers innervate skeletal muscles derived from the branchial arches?
Special visceral efferents (branchial motor)
[SVE]
4 cranial nerves are located ______ the pons, including I, II, III, and IV.
4 cranial nerves are located in the ______, including V, VI, VII, and VIII.
4 cranial nerves are located in the ______, including IX, X, XI, and XII.
Above
Pons
Medulla
What 4 cranial nerve nuclei are located medially?
III, IV, VI, XII
Modality(-ies) and associated function of CN I
Special sensory afferent: smell
Modality(-ies) and associated function of CN II
Special sensory afferent: visual info from retina
Modality(-ies) and associated function of CN III
Somatic motor (efferent): innervates levator palpebrae superioris, superior rectus, medial rectus, inferior rectus, and inferior oblique mm.
Parasympathetic motor (visceral efferent): innervates constrictor pupillae and ciliary mm.
Modality(-ies) and associated functions of CN IV
Somatic motor (efferent): innervation of superior oblique m. of the eye
Modality(-ies) and associated function of CN VI
Somatic motor (efferent): innervates lateral rectus m. of the eye
Modality(-ies) and associated functions of CN V
General sensory (afferent): general sensation from face and anterior scalp as far posteriorly as apex of the head, conjunctivae, bulb of the eye, mucous membranes of paranasal sinsuses, and nasal and oral cavities including the tongue and teeth, part of the external aspect of the TM, and from meninges of the anterior and middle cranial fossae
Branchial motor (efferent): innervates muscles of mastication — masseter, temporalis, medial and lateral pterygoid, tensor tympani, tensores veli palatini, mylohyoid, and anterior belly of the digastric mm.
Modality(-ies) and associated functions of CN VII
General sensory (afferent): sensation from variable area of pinna/auricle, external acoustic meatus, external TM, and small area of skin behind ear
Special sensory (afferent): taste from anterior 2/3 tongue and soft palate
Branchial motor (efferent): innervates muscles of facial expression
Parasympathetic motor (visceral efferent): stimulates lacrimal, submandibular, and sublingual glands as well as oral, nasal, and pharyngeal mucosal glands
Modality(-ies) and associated functions of CN VIII
Special sensory (afferent): balance (via vestibular nucleus), hearing (via cochlear nucleus)
Modality(-ies) and associated functions of CN IX
General sensory (afferent): sensation from posterior 1/3 tongue, tonsil, soft palate, fauces, uvula, mucosa of internal TM and cavity, mastoid air cells, auditory tube, upper pharynx
Visceral sensory (afferent): subconscious sensations from carotid body and carotid sinus
Special sensory (afferent): taste from posterior 1/3 tongue
Branchial motor (efferent): innervation of stylopharyngeus m.
Parasympathetic motor (visceral efferent): innervates parotid gland, controls blood vessels in carotid body and BP in carotid sinus
Modality(-ies) and associated functions of CN X
General sensory (afferent): general sensation from posterior meninges, concha, skin at back of ear and in external acoustic meatus, part of external TM, pharynx, larynx
Visceral sensory (afferent): sensation from lower pharynx, larynx, trachea, esophagus, thoracic and abdominal viscera, stretch receptors of aortic arch, chemoreceptors in aortic bodies
Branchial motor (efferent): innervates via pharyngeal plexus the pharyngeal constrictors, levator palati, salpingopharyngeus, palatopharyngeus, palatoglossus, and intrinsic mm of larynx
Parasympathetic motor (visceral efferent): smooth muscle and glands of pharynx, thoracic and abdominal viscera, cardiac muscle, aortic bodies
Modality(-ies) and associated functions of CN XI
Branchial motor (efferent): innervate sternomastoid and upper fibers of trapezius
Modality(-ies) and associated function of CN XII
Somatic motor (efferent): innervates 3/4 extrinsic mm of the tongue: genioglossus, styloglossus, hyoglossus, and ALL intrinsic mm of the tongue
[innervation of palatoglossus is with CN X]
Primary branches of CN V
V1 = ophthalmic
V2 = maxillary
V3 = mandibular
Primary branches of V1: ophthalmic
Lacrimal
Frontal
Nasociliary
Meningeal
Primary branches of V2: maxillary
Zygomatic Infraorbital Superior alveolar Nasociliary Palatine Meningeal
Primary branches of mandibular V3
Buccal Lingual Inferior alveolar Auriculotemporal Meningeal
Which primary branch of CN V is the only one with branchial motor function? What are its sub-branches?
Mandibular (V3)
Sub-branches: Medial pterygoid Lateral pterygoid Masseteric Deep temporal Mylohyoid
Cells of origin of CN I
Olfactory bulb
Cells of origin of CN II
Retinal photoreceptors
Nuclei associated with CN III
Oculomotor nucleus (SME)
Edinger-Westphal nucleus (VME)
Nucleus associated with CN IV
Trochlear nucleus
Nucleus associated with CN VI
Abducens nucleus
Nucleus and ganglion associated with CN V in terms of general sensory afferent innervation
Trigeminal nucleus
Trigeminal ganglion
Nucleus associated with CN V in terms of branchial motor efferent innervation
Masticator nucleus
What nuclei (and their associated ganglia) are associated with CN VII
GSA: Pontine trigeminal nucleus and spinal trigeminal nucleus (pain) + Geniculate ganglion
SSA: Nucleus solitarius + geniculate ganglion (taste buds)
BME: motor nucleus of CN VII
VME: superior salivatory nucleus + pterygopalatine and submandibular ganglia
Nuclei associated with CN VIII
Vestibular nucleus + vestibular ganglion and hair cells
Cochlear nucleus + spiral ganglion + cochlear hair cells
What nuclei (and their associated ganglia) are associated with CN IX?
GSA: spinal trigeminal nucleus + superior glossopharyngeal ganglion
VSA: nucleus of tractus solitarius + inferior glossopharyngeal ganglion
SSA: nucleus of tractus solitarius + inferior glossopharyngeal ganglion (taste buds)
BME: nucleus ambiguus
VME: inferior salivatory nucleus + otic ganglion
Nucleus ambiguus
What nuclei (and their associated ganglia) are associated with CN X
GSA: spinal trigeminal nucleus + superior vagal ganglion
VSA: nucleus of tractus solitarius + inferior vagal ganglion
BME: nucleus ambiguus
VME: dorsal vagal motor nucleus, nucleus ambiguus
What nucleus is associated with CN XI?
Accessory nucleus
What nucleus is associated with CN XII?
Hypoglossal nucleus
What 4 cranial nerves have general sensory (afferent) modality?
CN V
CN VII
CN IX
CN X
[all via trigeminal nucleus]
What 2 cranial nerves have visceral sensory (afferent) modality?
CN IX
CN X
[both via nucleus solitarius]
What 4 cranial nerves have special sensory (afferent) modality?
CN I CN II CN VII CN VIII CN IX
What 4 cranial nerves have somatic motor (efferent) modality?
CN III
CN IV
CN VI
CN XII
What 5 cranial nerves have branchial motor (efferent) modality?
CN V CN VII CN IX CN X CN XI
What 4 cranial nerves have parasympathetic (visceral) motor modality?
CN III
CN VII
CN IX
CN X
Pathway of CN I
Cribriform plate of ethmoid bone, synapses in olfactor bulb —> piriform cortex
Injury to CN I may cause ____, or loss of sense of smell
Anosmia
T/F: afferent fibers of CN I travel to the thalamus
False
Pathway of CN II
Optic canal of sphenoid bone
The optic n. arises from the _____ of the brain
Diencephalon
What 3 CN’s innervate ocular muscles? These 3 nerves all pass through what hole in the skull?
CN III: oculomotor n.
CN IV: trochlear n.
CN VI: abducens n.
All pass through the superior orbital fissure
The oculomotor n. moves the eye via 4 muscles:
Superior rectus m.
Medial rectus m.
Inferior rectus m.
Inferior oblique m.
How do each of the above muscles move the eye?
Superior rectus = moves eye up
Medial rectus = moves eye medially
Inferior rectus = moves eye down
Inferior oblique = superior rotation
What muscle, innervated by the oculomotor nerve, elevates the eyelid?
Levator palpebrae m.
The oculomotor n. provides parasympathetic innervation to the sphincter pupillae m. and the ciliary m. What is the difference in function of these 2 muscles?
Sphincter pupillae = pupillary constriction
Ciliary m. = near vision
The oculomotor n. innervates the superior rectus, medial rectus, inferior rectus, and inferior oblique. The other two muscles of the eye are innervated by what 2 cranial nn?
Superior oblique = CN IV
Lateral rectus m. = CN VI
What would be the result of oculomotor nerve palsy on the right side?
Right eye would exhibit downward and outward gaze, dilated pupil, and ptosis
What is the smallest cranial n.?
Trochlear (IV)
The trochlear n (IV) innervates the superior oblique m. of the eye. What is the action of this m?
Turns eye down/in
What would be the result of CN IV palsy? How do people compensate?
Strabismus and diplopia
Eye tilted outward and unable to look down/in
Head tilts AWAY from affected side to compensate
The abducens n (VI) innervates the lateral rectus m. What would be the effect of an abducens n. palsy?
Diplopia
Inability to laterally move the affected eye
What is the largest cranial n.?
Trigeminal (V)
What would be the result of a trigeminal n. (V) palsy?
Numb face (sensory)
Weak jaw (motor) — deviates TOWARDS affected side
Clinical manifestations of trigeminal neuralgia
Recurrent, sudden sharp pains
Tic douloureux (painful tic) — pains are so intense they cause wincing
The corneal reflex can be elicited by touching the eye with a Q-tip. The input is sensed by CN ______, and is transmitted to CN ____ bilaterally
The latter is what causes you to blink
V (V1)
VII
What CN has dual upper motor neuron innervation?
Facial n.
Somatic (branchial) motor for muscles of facial expression
Visceral (parasympathetic) motor for lacrimal gland, sublingual gland, and submandibular gland
Upper part of the face receives innervation from both sides of the brain
Lower part of the face receives innervation only from contralateral side of the brain
What branches of the facial nerve contribute to the muscles of facial expression?
Temporal n. Zygomatic n. Buccal n. Mandibular n. Cervical n.
What would be the result of CN VII palsy?
Loss of corneal reflex (motor output)
Loss of taste anterior 2/3
Hyperacusis (stapedius paralysis leading to intolerance of sound)
Idiopathic mononeuropathy of CN VII leading to sudden onset of facial paralysis, usually resolving in weeks to months
Bell’s Palsy
What happens with lesions to the cochlear portion of CN VIII?
Loss of hearing, tinnitus
What happens with lesions to the vestibular portion of CN VIII?
Vertigo, nystagmus, vomiting, nausea
What are the 6 branches of the glossopharyngeal n.?
Tympanic n. Branch to carotid sinus Branch to stylopharyngeus m. Tonsillar branches Lingual branches Pharyngeal branches
The stylopharyngeus is the only striated muscle that is innervated by the glossopharyngeal n. What is the action of this m?
Elevates pharynx for swallowing/gagging
Damage to the glossopharyngeal n. may lead to CN IX palsy and/or associated hemodynamic effects. Describe these
CN IX palsy = loss of gag reflex, loss of taste in posterior 1/3 tongue, loss of sensation upper pharynx
Hemodynamic effects = tricks body into thinking BP is low, resulting in unopposed sympathetic response —> increased BP and vasoconstriction
What nerve contributes to taste in the supra-epiglottic region?
Vagus n
Someone complaining of dysphagia may have an issue with what n?
Vagus n
What are the 3 vagal nuclei and their modalities/functions?
nucleus Solitarius = visceral Sensory info (e.g., taste, baroreceptors, gut distention)
nucleus aMbiguus = Motor innervation of pharynx, larynx, upper esophagus
Dorsal motor nucleus = sends autonomic (parasympathetic) fibers to heart, lungs, upper GI
Effects of Vagus n. palsy
Hoarseness, dysphagia, dysarthria Loss of gag reflex Loss of sensation pharynx and larynx Weak side of palate collapse (lower) Uvula deviates AWAY from affected side
Hemodynamic effects of vagus n. damage
Unopposed sympathetic stimulation of the heart, resulting in increased HR, BP, etc.
What is the most common cause of syncope?
Vasovagal syncope — triggered by vagus n. —> increase parasympathetic outflow, decreasing HR and BP which leads to fainting
[many things can trigger the vagus n. into this response including hot weather, prolonged standing, pain, sight of blood, etc.]
What would be the effects of accessory n. palsy?
Difficulty turning head toward normal side (SCM) and shoulder droop (affected side)
What would be the result of hypoglossal n. palsy?
Protrusion of tongue TOWARD the affected side
The tongue receives motor, taste, and general sensory from what CNs?
Motor: hypoglossal (XII)
Taste: anterior 2/3 from facial (VII), posterior 1/3 from glossopharyngeal (IX), tongue root from vagus (X)
General sensory: anterior 2/3 from mandibular branch of trigeminal (V3), posterior 1/3 from glossopharyngeal (IX), tongue root from vagus (X)
The _____ ____ separates the innervation of the anterior 2/3 from the posterior 1/3 of the tongue
Terminal sulcus
What provides afferent and efferent output for corneal reflex?
Afferent = V1
Output = VII (blinking)
What provides afferent and efferent output for lacrimation reflex?
Afferent = V1
Efferent = VII (tearing)
What effect does a damaged V1 have on the lacrimation reflex?
No reflex tears can be produced but you can still produce emotional tears
What provides afferent and efferent output for gag reflex?
Afferent = IX
Efferent = X (gagging)
What provides afferent and efferent output for jaw jerk reflex?
Afferent = V3
Efferent = V3 (trigeminal reflex)
[place finger on pt’s chin and tap finger, jaw will jerk upwards]
What provides afferent and efferent output for pupillary reflex?
Afferent = II
Efferent = III (constrict pupil)
List all CN’s
I: Olfactory II: Optic III: Oculomotor IV: Trochlear V: Trigeminal VI: Abducens VII: Facial VIII: Vestibulocochlear IX: Glossopharyngeal X: Vagus XI: Accessory XII: Hypoglossal
List modalities of all cranial nerves in terms of sensory, motor, or both
[Some Say Marry Money But My Brother Says Big Boobs Matter Most]
I: Olfactory = Sensory II: Optic = Sensory III: Oculomotor = Motor IV: Trochlear = Motor V: Trigeminal = Both VI: Abducens = Motor VII: Facial = Both VIII: Vestibulocochlear = Sensory IX: Glossopharyngeal = Both X: Vagus = Both XI: Accessory = Motor XII: Hypoglossal = Motor
What CN(s) is/are associated with the anterior cranial fossa?
CN I
What CN(s) is/are associated with the middle cranial fossa (through sphenoid bone)?
CN II
CN III
CN IV
CN VI
CN V1
CN V2
CN V3
What CN(s) is/are associated with the posterior cranial fossa (through temporal or occipital bone)?
CN VII
CN VIII
CN IX
CN X
CN XI
CN XII
What CNs pass through the optic canal?
CN II
CN II passes through the optic canal with what vessel?
Opthalmic a.
What CN’s pass through the superior orbital fissure?
CN III
CN IV
CN VI
CN V1
What CN passes through the foramen rotundum?
CN V2
What CN passes through the foramen ovale?
CN V3
What vessel passes through the foramen spinosum?
Middle meningeal a.
What CNs pass through the internal auditory meatus?
CN VII
CN VIII
What CNs pass through the jugular foramen?
CN IX
CN X
CN XI
CN’s IX, X, and XI pass through the jugular foramen with what vessel?
Jugular v.
What CN passes through the hypoglossal canal?
CN XII
