Cranial Nerves Flashcards
Associated cranial foramen for CN I
Cribiform plate
Associated cranial foramen for CN II
Optic canal
Associated cranial foramen for CN III, IV, V1, VI
Superior orbital fissure. Note: all of these nerves pass through the cavernous sinus as well.
Associated cranial foramen for CN V2
Foramen Rotundum
Associated cranial foramen for CN V3
Foramen Ovale (for divisions of the trigeminal nerve think “S tanding R oom O nly”)
Associated cranial foramen for CN VII, VIII
Internal acoustic meatus
Associated cranial foramen for CN IX, X, XI
Jugular foramen
Associated cranial foramen for CN XII
Hypoglossal canal
Function of CN I: olfactory
Smell
Function of CN II: optic
Vision
Function of CN III: oculomotor
- Eye movement
- “Parasympathetic” ciliary and pupillary sphincter mm
Note: mm is used as the abbreviation for “muscles”.
Function of CN IV: trochlear
Contraction of superior oblique muscle
Function of CN V1: trigeminal—ophthalmic branch
Sensation from nose to forehead
Function of CN V2: trigeminal—maxillary branch
Sensation from lateral nose, upper lip, superior buccal area
Function of CN V3: trigeminal—mandibular branch
- Sensation from areas of the lower face not covered by V1 and V2
- Movement of the Muscles of Mastication (Masseter, teMporalis, Medial, and lateral pterygoids), tensor veli palatini, and tensor tympani
Function of CN VI: abducens
Contraction of lateral rectus muscle
Function of CN VII: facial
- Parasympathetic—lacrimal, submandibular, and sublingual glands
- Mm of facial expression, stapedius, stylohyoid, and the posterior belly of the digastric muscle
- Taste—anterior two-thirds of tongue
- Sensation—skin of external ear
Function of CN VIII: vestibulocochlear
Hearing and sense of balance
Function of CN IX: glossopharyngeal
- Parasympathetic—parotid gland
- Motor—stylopharyngeus mm
- Taste—posterior one-third tongue
- Sensation—parotid gland, carotid body and sinus, pharynx, and middle ear
- Cutaneous sensation—external ear canal
Function of CN X: vagus
- Parasympathetic—trachea, bronchi, heart, GI tract
- Contraction of laryngeal, pharyngeal, and esophageal striated mm
- Taste—epiglottis and palate
- Sensation—trachea, GI tract
- Cutaneous sensation—external ear
Function of CN XI: accessory
Movement of sternocleidomastoid and trapezius muscles
Function of CN XII: hypoglossal
Contraction of muscles of tongue
Which three cranial nerves are purely sensory nerves?
- CN I
- CN II
- CN VIII
Which five cranial nerves are purely motor nerves?
- CNIII
- CNIV
- CNVI
- CNXI
- CNXII
Which four cranial nerves have both motor and sensory components?
- CNV
- CNVII
- CNIX
- CNX
Which two cranial nerves are rostral to the midbrain?
- CNI
- CNII
Which two cranial nerve nuclei are located in the midbrain?
- CNIII
- CNIV
Which four cranial nerves have at least a portion of their nuclei in the pons?
- CNV
- CNVI
- CNVII
- CNVIII
Which seven cranial nerves have at least a portion of their nuclei in the medulla?
- CN V
- CN VI
- CN VII
- CNVIII
- CN IX
- CNX
- CNXII
Name the only cranial nerve that crosses the midline and exits the brainstem posterior to the ventricular system:
CN IV—exits the brainstem posteriorly and crosses the midline after exiting the caudal midbrain
What nucleus serves as the origin of preganglionic parasympathetic fibers projecting to the ciliary ganglion?
Edinger-Westphal nucleus of CN III
What visceral sensory nucleus, located in the medulla, is a relay center for taste, sensory input from the carotid sinus, carotid body, and the vagus nerve?
Nucleus Solitarius
What visceral motor nucleus, located in the medulla, is involved in coordinating swallowing and speech?
Nucleus aMbiguus
Which are the afferent and efferent limbs of the corneal reflex?
CN V1 and CN VII
Which are the afferent and efferent limbs of the pupillary light reflex?
CN II and CN III
Which are the afferent and efferent limbs of the gag reflex?
CN IX and CN X
What lesion causes Ipsilateral blindness
Transection of the optic nerve
What lesion causes Binasal hemianopia
Bilateral lateral compression of optic chiasm
What lesion causes Bitemporal hemianopia
Midsagittal transection or midline pressure on the optic chiasm (often caused by a pituitary tumor)
What lesion causes Right hemianopia without macular sparing
Transection of the left optic radiation
What lesion causes Right upper quadrantanopia
Transection of the lower division of the left optic radiation
What lesion causes Right lower quadrantanopia
Transection of the upper division of the left optic radiation
What lesion causes Right hemianopia with macular sparing
Destruction of the left visual cortex
What are five key structures of the pupillary light reflex pathway?
- Ganglion cells of the retina
- Pretectal nucleus of the midbrain
- Edinger-Westphal nucleus
- Ciliary ganglion
- Postganglionic parasympathetic fibers of CN III
What are four key structures of the pupillary dilation pathway?
- Paraventricular nucleus of the hypothalamus
- Ciliospinal center of Budge at the level of T1 to T2
- Superior cervical ganglion
- Postganglionic sympathetic fibers traveling along the internal carotid artery and its branches to the eye
What part of the cortex is responsible for voluntary eye movements?
Frontal eye field (Brodmann area 8)
What side will a patient’s eyes deviate toward if there is a lesion of the right frontal eye field?
Right side (“Look toward the lesion of frontal eye fields”)
What structure connects the nucleus of CN VI and the nucleus of CN III?
Medial longitudinal fasciculus (MLF)
What type of lesion will result in medial rectus palsy (inability to adduct the eye) on attempted lateral gaze but normal adduction on accommodation?
Intranuclear ophthalmoplegia (a lesion of the MLF)
What classic idiopathic lesion is characterized by ptosis, miosis, and anhydrosis?
Horner syndrome
Name the condition characterized by a pupil that will accommodate but cannot react to light:
Argyll-Robertson pupil (associated with tertiary syphilis, lupus, and diabetes mellitus)
Name the condition caused by a lesion in the afferent fibers of the light reflex pathway:
Marcus Gunn pupil
What are the primary sensory receptors of the auditory pathway?
Inner hair cells of the organ of Corti
Where does the auditory pathway terminate?
Bilateral input from both auditory tracts terminates in primary auditory cortex in superior temporal gyrus (Brodmann areas 41 and 42)
What type of cells are responsible for relaying auditory stimuli from the organ of Corti to the cochlear nuclei?
Bipolar cells of the spiral or cochlearganglion
What thalamic nucleus plays a key role in relay of impulses from the cochlear nuclei to higher cortical centers?
Medial geniculate body of the thalamus
What pontine nucleus plays a key role in sound localization?
Superior olivary nucleus
What are key structures of the hearing pathway?
Cochlear → cochlear nucleus → decussating fibers in Trapezoid body → superior olivary nucleus → lateral lemniscus → inferior colliculi → medial geniculate nucleus → primary auditory cortex
Conduction deafness is caused by a lesion of which components of the auditory system?
External auditory canal, tympanic membrane, or the middle ear
Sensorineural deafness is caused by a lesion of which components of the auditory system?
Cochlea, cochlear nerve, or the cochlear nuclei
Patients with presbycusis have trouble hearing what types of sounds?
High-frequency sounds
Which cells of the vestibular system respond to angular acceleration and deceleration?
The hair cells of the three semicircular canals
What structures of the vestibular system respond to linear acceleration and deceleration?
The hair cells of the utricle
What type of cells are responsible for relaying vestibular stimuli from the hair cells to the vestibular nuclei?
Bipolar cells of the vestibular ganglion
What structures provide input to the vestibular nuclei?
Hair cells of the semicircular canal, hair cells of the utricle, and the flocculonodular lobe of the cerebellum
What structures receive signals from the vestibular nuclei?
The thalamus, spinal cord, cerebellum, and CNs III, IV, and VI
