Exam #4 Info Flashcards
There are __ pairs of cranial nerves. Explain where they exit relative to the brainstem
Twelve11 exit anterior1 exits posterior
What areas of the body do the cranial nerves innervate?
HeadNeckThoraxUpper abdomen
What are the three basic functions of cranial nerves?
Motor innervationSomatosensory and special sensory innervationParasympathetic innervation
Cranial N I Name, Related function, and Connection to brain
OlfactoryFunction: smellConnection to brain: inferior frontal lobe
Cranial N IIName, Related function, and Connection to brain
OpticFunction: visionConnection to brain: diencephalon
Cranial N IIIName, Related function, and Connection to brain
OculomotorFunction: Moves eye up and down, medially; raises upper eyelid; constricts pupil; adjusts the shape of the lens of the eyeConnection to brain: midbrain (anterior)
Cranial N IVName, Related function, and Connection to brain
TrochlearFunction: moves eye medially and downConnection to brain: midbrain (posterior)
Cranial N VName, Related function, and Connection to brain
TrigeminalFunction: facial sensation, chewing, sensation from TMJConnection to brain: pons (lateral)
Cranial N VIName, Related function, and Connection to brain
AbducensFunction: abducts the eyeConnection to brain: between pons and medulla
Cranial N VIIName, Related function, and Connection to brain
FacialFunction: facial expression, closes eye, tears, salivation, tasteConnection to brain: between pons and medulla
Cranial N VIIIName, Related function, and Connection to brain
VestibulocochlearFunction: sensation of head position relative to gravity and head movement; hearingConnection to brain: between pons and medulla
Cranial N IXName, Related function, and Connection to brain
GlossopharyngealFunction: swallowing, salvation and tasteConnection to brain: medulla
Cranial N XName, Related function, and Connection to brain
VagusFunction: regulates viscera, swallowing, speech, tasteConnection to brain: medulla
Cranial N XIName, Related function, and Connection to brain
AccessoryFunction: Elevates shoulders, turns headConnection to brain: spinal cord and medulla
Cranial N XIIName, Related function, and Connection to brain
HypoglossalFunction: moves tongueConnection to brain: medulla
Cranial N I: OlfactoryNormal function
Sensory
Olfactory Nerve
From nasal chemoreceptors to olfactory bulbIn roof of the sinus in porous bone
Olfactory tract
Is what’s seen on gross brain dissectionCarries the smell message to the frontal lobe
Cranial N I: OlfactoryDysfunction
Damage with TBICannot smellLink with Parkinson’s and Alzheimer’s
Cranial N II: OpticNormal function
SensoryConscious vision: Optic tract –> Occipital cortexReflex response: Optic tract –> Midbrain nuclei (superior colliculus)
Optic chiasm
Next location in visual pathway after optic NWhere half of the axons from each retina cross the midline
Optic tract
Connects the axons to the thalamus
Corticobulbar Tract
Cranial Nn cortical tractCortical control over some cranial Nn from the cortex
Cranial nerves are a type of __ nerve
Peripheral
All sensory pathways connect through the ___.
Thalamus
Cranial N II: OpticDysfunction
BlindnessLose depth perceptionDisruption of pupillary light reflex
Cranial Nn III, IV, and VI: oculomotor, trochlear and abducensNormal function
Motor control of six extra ocular musclesParasympathetic innervation of the eyePupillary Light ReflexConsensual Light ReflexAccommodation Reflex
CN III controls which extraocular muscles? What eye movements does it result in?
Medial rectusSuperior rectusInferior rectusInferior obliqueAdducts, elevates and depresses the eye
CN IV controls which extraocular muscles? What eye movements does it result in?
Superior obliqueLook in toward the tip of the nose
CN VI controls which extraocular muscles? What eye movements does it result in?
Lateral rectusMoves the eye laterally
Medial Longitudinal Fasciculus
Wiring bundle that interconnects all CN on both sides of the brainstem and integrates that with the inner ear
What CN does the parasympathetic innervation of the eye travel with?
CN III
What affect does the parasympathetic innervation of the eye have?
Constricts pupil (via pupillary sphincter)Increases curvature of lens for near vision (via ciliary muscle)
Pupillary Light Reflex
Constricts the pupil in the same eye to lightReflex onlyOptic (afferent)Oculomotor (efferent)
Consensual Light Reflex
Constricts the opposite pupil to lightReflex onlyOptic (afferent)Oculomotor (efferent)
Accommodation Reflex
Compensations to focus in near visionDriven by conscious visionPupils constrictEyes converge (adduct)Lens becomes more convex
Cranial N III: OculomotorDysfunction
PtosisAffected eye looks down and outDiplopiaDifficulty moving eye medially, downward and upwardDilation of pupilLoss of pupillary light reflex and consensual light reflexLoss of constriction of pupil for focus on near object
Cranial N IV: TrochlearDysfunction
Cannot look down and inExtorsion
Cranial N VI: AbducensDysfunction
Inability to abduct eyeResting position of eye drifts medially
Cranial N V: TrigeminalNormal function
Mixed sensory and motor3 branchesAfferent pathwaysEfferent pathwaysReflexes
Name the three branches of the trigeminal N
Ophtalmic: of the eyeMaxillary: top of the jawMandibular: bottom of the jaw
Describe the 4 afferent pathways of the trigeminal N.
Discriminitive touch (face, eye, tongue): sensory receptor –> somatosensory cortexProprioception: sensory receptor –> reticular formationNociception (fast pain): nociceptor –> somatosensory cortexNociception (slow pain): nociceptor –> limbic system and cortex
Describe the efferent pathway of the trigeminal N
Muscles of mastication
Describe the two reflexes of the trigeminal N
Blink reflex: input CN V, output CN VIIJaw jerk reflex: input CN V, output CN VII
Cranial N V: TrigeminalDysfunction
Loss of touch, pain, temperature on facePossible loss of blink reflexPossible loss of jaw jerk reflex (jaw deviates toward involved side with active opening)Trigeminal Neuralgia
Trigeminal Neuralgia
Trigeminal N painAllodyniaHyperalgesia
Cranial N VII: FacialNormal Function
Motor function: facial expression musclesParasympathetic: salivary, nasal and lacriminal glandsSensory: taste sensation from anterior 2/3 of tongue
Cranial N VII: FacialDysfunction
Paralysis or paresis of all ipsilateral muscles of facial expression (Bell’s Palsy)
Is Bell’s Palsy a result of UMN or LMN damage?
LMN
Cranial N VIII: VestibulocochlearNormal Function
SensoryTransduction of soundFrequency codingAuditory function within the CNS
Name the two divisions of Cranial N VIII: Vestibulocochlear
Vestibular divisionCochlear division
Explain the transduction of sound.
Air waves are converted to water waves which bend hair cells to create APDifferent set of hair cells for each frequency you hear
Frequency Coding
Different part of the cochlea for every frequency you hear
Name the 3 auditory functions of the vestibulocochlear nerve within the CNS
1) Orientation of head and eyes toward sound (inf colliculus helps localize)2) Increase arousal within CNS (reticular formation)3) Conscious awareness and recognition of sounds (thalamus to auditory cortex)
Cranial N VIII: VestibulocochlearDysfunction
Dizziness/dysequilibriumHearing Loss Difficulty locating sounds in spaceTinitus
Name the two types of hearing loss associated with Vestibulocochlear N Dysfunction
Conductive hearing lossSensorineural hearing loss
Describe conductive hearing loss
Cannot convert air waves to water wavesExcessive wax: prevents the eardrum from moving so air waves cannot get to the middle earOtitis media: air waves reach the middle ear but do not change into water waves
Otitis media
Middle ear infection or fullness/inflammation
Describe sensorineural hearing loss
Problem in sensation or nervous system pathwayHair cells that create AP can become damaged or dieDamage to receptor cells or cochlear nerve
Causes of sensorineural hearing loss
Peripheral nerve (CN VIII)Acoustic neuromaTinnitusCochlear Nuclei/central pathways (i.e. brainstem stroke)
Acoustic neuroma
Tumor that compresses CN VIII almost exclusively so that the AP can never get in to the brainstem
Tinnitus
Ringing in the earSign of damage to the hearing pathway in the ear
Cranial N IX: GlossopharyngealNormal function
Mixed sensory, motor, and autonomic
The sensory component of the glossopharyngeal nerve consists of ___.
Somatosensation from posterior tongue, soft palate and pharynx (sensory part of the gag and swallow reflexes)Taste sensation from the posterior tongue (bitter taste)
Cranial N IX: GlossopharyngealDysfunction
Loss of afferent gag reflexLoss of afferent swallow reflexDecrease salivation
What is a consequence of the loss of a swallow reflex?
Aspiration
Cranial N X: VagusNormal function
Mixed sensory, motor and autonomic
The sensory component of the Vagus N goes to __.
LarynxPharynxViscera
The motor component of the Vagus N goes to __.
LarynxPharynx
The autonomic component of the Vagus N goes to __.
LarynxPharynxTracheaLungsHeartUpper GIPancreasGall bladderLiver
Cranial N X: VagusDysfunction
Difficulty speakingHoarse voiceDifficulty swallowingAssymetric elevation of soft palateLoss of efferent gag reflexLoss of efferent swallow reflexPoor digestion
Cranial N XI: AccessoryNormal function
Motor: trapezius and sternocleidomastoid
Cranial N XI: AccessoryDysfunction of LOWER motor neuron
“Flaccid” paralysis of ipsilateral upper trapezius and sternocleidomastoid
Cranial N XI: AccessoryDysfunction of UPPER motor neuron
“Spastic” paresis of contralateral upper trapezius and sternocleidomastoid
Cranial N XII: HypoglossalNormal Function
Motor: intrinsic and extrinsic muscles of the tongue
Cranial N XII: HypoglossalDysfunction
Atrophy of ipsilateral tongueTongue drifts toward side of lesion when “stuck out”Difficulty speaking and swallowing
Name the three stages of swallowing
Oral stageLaryngeal/Pharyngeal stageEsophageal stage
Which cranial nerves are involved in the oral stage of swallowing and what is their function?
V: moves the jawVII: keeps the mouth closedXII: tongue moves food back and forth to be chewed up and then to the throat for swallowing
Which cranial nerves are involved in the laryngeal/pharyngeal stage of swallowing and what is their function?
IX: sense the presence of foodX: starts the swallow when the context is right
Which cranial nerves are involved in the esophageal stage of swallowing and what is their function?
X: closes the windpipe and squeezes the food down the esophagus
What structures are involved in speaking and which cranial nerve corresponds with that part?
Larynx: CN XSoft palate: CN XLips: CN VIIJaw: CN VTongue: CN XII
Any cranial nerve that has ____ function and innervates ___ is a ___ motor neuron.
SomatomotorSkeletal/striated muscles in the head or neckLower
Name the three systems controlling cranial nerve lower motor neurons.
Corticobulbar Tract (upper motor neurons)Descending limbic pathwaysSensory input (reflexes)
Three inferior to superior divisions of the brainstem and their cranial nerves
Medulla: CN IX, X, XI, XIIPons: CN V, VI, VII, VIIIMidbrain: CN III, IV
Three anterior to posterior divisions of the brainstem
Base (basilar): motorTegmentum: sensoryTectum: eye movements and movements of the head
Describe the pyramids of the medulla
VentralWhite matterCorticospinal tract Voluntary motor
The dorsal medulla contains __ tracts
Sensory tracts of touch and proprioception
The basilar portion of the medulla contains __. (2)
Corticospinal tractsMedial lemniscus
The tegmentum portion of the medulla contains __.
Spinothalamic tractsTigeminothalamic tractsReticular formationAutonomic “control” nucleiCranial nerve nuclei IX, X, XII
The ventral pons contains __.
“Bulge” of pontine nuclei and pontocerebellar fibersCranial nerve roots V, VI, VII, VIII
The dorsal pons contains __.
Cerebellar peduncles
The basilar portion of the pons contains __.
Corticospinal tractPontine nuclei (origin of pontocerebellar fibers)Corticobrainstem tract
The tegmentum portion of the pons contains __.
Medial lemniscus (touch and proprioception)Spinothalamic tractsTrigeminothalamic tractsReticular formationAutonomic “control” nucleiCranial nerve nuclei (V, VI, VII, VIII)
The ventral midbrain contains ___.
Cerebral pedunclesCranial nerve root (III)
The dorsal midbrain contains __.
Superior colliculiInferior colliculiCranial nerve root (IV)
The basilar portion of the midbrain contains __.
Cerebral pedunclesSubstantia nigra
The tegmentum portion of the midbrain contains __.
Red nucleusPedunculopontine nucleusOculomotor complex (CN III, IV)Periaqueductal gray
The tectum portion of the midbrain contains __.
Superior colliculiInferior colliculi
3 functions of the reticular formation
Integrates sensory and cortical information: helps with motor planning and regulating moodRegulates somatic motor activity, autonomic function and consciousnessModulates nociceptive/pain information
What other area of the brain does the reticular formation work with to make the motor plan?
Basal ganglia
2 main functions of the cerebellum
Coordination of movement (gross and fine)Motor planning
Segmental damage in the brainstem
Cranial nerve damageEX: Cranial N VIILower motor neuron damage”All of one side” of the face is paralyzedBell’s palsy
Vertical tract damage in the brainstem
Cortex or corticobrainstem damageUpper motor neuron damage”Lower half of one side” of face paralyzed
If you cannot move the upper OR lower part of the face, what kind of damage to the brainstem is it? (3 terms)
SegmentalCranial N VII damageLower motor neuron damage
If you can move the eye but NOT the mouth on one side of the face, what kind of damage to the brainstem is it? (3 terms)
Vertical tractCortex or corticobrainstem damageUpper motor neuron damage
What 3 tracts and/or nerves will damage to the anteromedial medulla affect?
Corticospinal tractMedial LemniscusHypoglossal N
What affect will damage to the corticospinal tract in the anteromedial medulla result in?
Paralysis of the arm/trunk/legContralateral
What affect will damage to the medial lemniscus tract in the anteromedial medulla result in?
Loss of touch from the bodyContralateral
What affect will damage to the hypoglossal N in the anteromedial medulla result in?
Paralysis of the tongueIpsilateralLower motor neuron damageAtrophy of denervation
In 99% of the brainstem, one sided damage will yield __.
Vertical tract damage = contralateral signs and symptoms (UMN damage)-Dorsal column medial lemniscus-Spinothalamic-CorticospinalCranial N nuclei damage = ipsilateral signs and symptoms (LMN damage)
How can brainstem region damage affect vital function?
Can also damage the cardiovascular and respiratory control centers int he medullaAutonomic signs are ipsilateral with one sided damage to the pons and/or medulla
Name the 4 D’s of Brainstem Region Dysfunction
DysphagiaDysarthriaDiplopiaDysmetria
Dysphagia:DefinitionCranial N InvolvementArea of brain affected
Difficulty swallowingCranial Nerves IX, XProblem of the medulla because that is where CN IX, X are
Dysarthria:DefinitionCranial N InvolvementArea of brain affected
Difficulty in the mechanical production of speechCranial Nerves V, VII, X, XIIEspecially with damage to the pons and medulla
Diplopia:DefinitionCranial N InvolvementArea of brain affected
Double visionCranial Nerves III, IV, VIDamage to the midbrain and top of medulla
Dysmetria:DefinitionTract InvolvementArea of brain affected
Cannot accurately hit a targetSpinocerebellar tract (or bottom of brainstem)Cerebellum-knows what you want to do but not what you are really doing
2 functions of the vestibular system
Keep us visually and physically steady in the worldMaintenance of balance and EQ
2 components of the vestibular system
Peripheral (inner ear and CN VIII)Central (pathway in brainstem and brain)
Semicircular canals
Almost circles off the base of the vestibular apparatus can sense any direction your head moves
Direction of the 3 semicircular canals on each side of the head
Anterior: 45 degrees out toward the frontPosterior: 45 degrees toward the backHorizontal: tipped up 30 degrees