Cranial Nerves, Vison, Audition, and Equilibrium Flashcards
Cranial Nerve I
Name, Type, and Function
- Olfactory
- sensory
- conveys sense of smell
- Damage = distortion to smell and taste
Cranial Nerve II
Name, Type, and Function
- Optic
- Sensory
- vision
- Damage = various vision impairments
Cranial Nerve III
Name, Type, and Function
- Oculomotor
- Motor
- Moves 4/6 extraocular nerves
- Parasympathetic NS
- Accomodation of the lens
- Pupillary constriction
- eyeball convergence
- Damage = diplopia, strabismus (incoordination of eyes), ptosis (eyelid drooping) and mydriasis (pupil dilation), inability to open eye, copensatory head tilting
Cranial Nerve IV
Name, Type, and Function
- Trochlear
- Motor
- moves superior oblique extraocular muscle
- Damage = diplopia
- affected eye adducted and elevated
- eye cannot move downwards properly
Cranial Nerve V
Name, Type, and Function
- Trigeminal nerve (three parts)
- Sensory
- brings in sensory information from the face and jaw
- Motor
- moves the muscles of mastication (masseter)
- Damage = trigeminal neuralgia (pain), cluster headache, trigeminal zoster
Cranial Nerve VI
Name, Type, and Function
- Abducens nerve
- Motor
- moves the lateral rectus extraocular muscle
- Damage = diplopia
- eye is pulled towards the nose
Cranial Nerve VII
Name, Type, and Function
- Facial nerve
- Sensory
- taste from anterior 2/3 of tongue
- Motor
- moves all muscles of facial expression
- Parasympathetic NS
- stimulates salivation and lacrimal glands
- Damage = facial palsy, Bell’s palsy
- drooping of affected side of face
Cranial Nerve VIII
Name, Type, and Function
- Vestibulocochlear
- Sensory
- brings auditory (hearing) information from the cochlea
- Brings in angular acceleration (balance) info from semicircular canals
- Brings in static acceleration (balance) info from vestibule
- Damage = sensation of spinning, loss of hearing
Cranial Nerve IX
Name, Type, and Function
- Glossopharyngeal nerve
- Sensory
- taste in the posterior 1/3 of the tongue
- Motor
- stimulates skeletal muscle in pharynx ad larynx for swallowing
- Parasympathetic NS
- Brings in cardiovascular sensory info from carotid sinus
- [blood pressure (baroreceptors) and blood chemistry chemoreceptors)}
- Stimulates salivation of the parotid salivation gland
- Damage = absence of gag reflex, deviation of uvula
Cranial Nerve X
Name, Type, and Function
- Vagus Nerve
- Sensory
- brings in taste from the base of the tongue and oropharynx
- Motor
- stimulates skeletal muscles in the pharynx and larynx in swallowing
- Parasympathetic NS
- sensory and motor for most of the viscera; control stopes at the level of the colon
- Damage = increase BP, increase HR, difficulties in swallowing
Cranial Nerve XI
Name, Type, and Function
- Accessory
- Motor
- stimulates skeletal muscle in the pharynx and larynx for swallowing
- Stimulates the sternocleidomastoid muscle
- Stimulates the trapezius muscle
- Damage = ipsilateral weakness of the trapezius, inability to raise the scapula, weakness of sternocleidomastoid muscle
Cranial Nerve XII
Name, Type, and Function
- Hypoglossal
- Motor
- stimulates the tongue
- Damage = tongue deviates to the side of damage
Nerves that control eye movement
CN III - oculomotor -
CN IV - trochlear -
CN VI - abducens -
Nerves that control taste
- VII - facial - anterior 2/3
- IX - glossopharyngeal - posterior 1/3
- X - vagus - base/oropharynx
Nerves that control salivation
- VII - (facial) sublingual, submandibular
- IX - (Glossopharyngeal) parotid
Nerves that control swallowing
- involuntary phase
- IX - glossopharyngeal
- X - vagus
- XI - accesory
- voluntary phase
- XII - hypoglossal
Nerves that control the parasympathetic NS
- III - occularmotor - close vision
- VII - facial - salivation; lacrimal
- IX - glossopharyngeal - sensory in: CV pressure/chemistry salivation
- X - vagus - rest and digest
Exteroreceptors
- by which one perceives the outside world
- skin, mucus membranes, special senses
Interoreceptors
- by which one perceives pain, hunger, etc., and the movement of internal organs
- Proprioceptors in muscle spindles, golgi tendon organ, joint capsules, and inner ear
- Visceroceptors (in organs or passageways): baroreceptors, stretch receptors, chemoreceptors
The attributs of sensation are
- Modality
- Quality of the modality
- Quantity
- Localization of projection
Modality is
the type of sensory information, including exteroceptive, proprioceptive or visceroceptive
Quality of modality refers to
the exact kind and depth of modality
i.e. with touch it can be temperature, light touch, deep pressure, vibration.
Quality is carried to the brain on a specific tract called labeled line coding.
The sensation attribute of quantity is
the intensity of a threshold potential as coded by frequency of the action potentials; either by population coding or labeled line coding
The attribute of sensation, localization of projection is
- the stimulus affects a receptive field.
- Info from the receptive field is then carried to a specific region of the primary sensory area of the parietal lobe in the brain (post central gyrus) providing awareness of stimulation
What is the law of specific nerve energies
- All receptors will respond to a very strong stimulus
- regardless of type or strength of stimulaus to a given receptor, the receptor will always respond the same.
- eg: application of pressure to the eyeball will result in a visual sensation event of “seeing light”
The Law of adequate stimulus
aka optimal stimulus, unique stimulus to which a particular receptor responds and is most sensitive
eg: light is the most optimal stimulus for the retina
Generator potential
- In response to the stimulus, the receptor undergoes transduction; the process of converting the mechanical stimulus into an action potential
- A receptor, which are specialized dendrites, cannot conduct an action potential. Instead, they open channels or release neurotransmitters causing depolarization and an action potential to begin along the ason of a sensory neuron.
Pacinian corpuscle receives info on
deep pressure and vibration
Meissner’s corpuscles receive info on
light touch
The neural pathway of olfaction
- Receptor: olfactory receptor cells
- Transduction
- gas binds to receptors
- Na+ channels open and begins depolarization
- Neurotransmitter is dumped into mitral cells of olfactory bulb releasing AP
- Sensory neuron : AP carried via olfactory tract (CN I)
- CNS Area
- CN I
- Thalamus
- Olfactory complex in Temporal lobe
- Limbic system: analyze emotional aspects
Neural pathways of Taste
- Receptors: gustatory or taste cells of taste buds
- Transduction
- Saliva dissolves food
- Molecule binds to microvilli
- Chemical channels open
- Taste cell dups NT onto dendrite of sensory neuron
- Sensory Neurons
- VII (facial)
- IX (glossopharyngeal
- X (Vagus)
- CNS area
- Gustatory cortex in parietal lobe
- Hypothalamus and limbic system, appreciate the taste
General structure and function of auditory system
- Outer ear
- pinna
- external auditory cana
- Middle ear
- malleus, incus, stapes
- Eustachian tube
- Inner ear
- Cochlea
- semicirucular canals
- vestibule
Overall Pathway of auditory signals
- External auditory canal
- Typmanic membrane
- malleus
- incus
- stapes
- oval window
- cochlea
Transduction of auditory signals in the cochlea
- vibration caused by movement of the stapes in the oval window causes fluid movement
- Fluid movement causes the basilar membrane, and thus the organ of corti to move
- Hair cells on the organ of corti bend as they strike the tectorial membrane
- Ca+ channels open and depolarize hair cells
- NT dumped onto dendrites of CN VIII
Detection of sound frequency in the cochlea
- Fibers near the apex (beginning) are floppy; sense 20 Hz, low pitch
- Fibers near the base (end) are short and stiff; sense 20,000 Hz high pitch
Intensity of auditory signals are measured in ______. They are coded by ________.
- decibels
- frequency of APs
Auditory nerve pathways
- CN VIII
- sensory info is duplicated
- sent to both sides of the brainstem upon entering
- Inferior colliculus
- Medial geniculate body of thalamus
- Auditory cortex in temporal lobe
The organs that sense static equilibrium are
- Otolithiic organs in the vestibule
- Utricle
- Saccule
The Utricle senses
- Linear acceleration in the horizontal plane
The Saccule senses
- Linear acceleration in the verticle plane
The receptors in the utricle and saccule are ________.
They consist of _______ and _________.embedded in the overlying membrane.
- macula
- stereocilia
- kinoclium
With linear movement head movement, ______ and membrane move.
This causes the ______ to bend
- otoliths
- kinocilia
When stereocilia bend toward the kinocilium, ________ occurs.
depolarization
When steriocilia bend away from kinocilium, ________ occurs
hyperpolarization
When you accelerate (spin) towards the left the fluid moves _______.
Depolarization occurs in the ____________.
Hyperpolarization occurs in the ___________.
While spinning, nystagmus has a horizontal fast component to the ______ and a slow component to the ______.
- fluid moves to the right
- Depolarization occurs in the left lateral canal
- Hyperpolarization occurs in the right lateral canal
- Left toward the direction of spin
- Right opposite of the direction of spin
- **IF the direction of spin were oppoite, the above directions would as well.
While spinning, nystagmus has a horizontal fast component to the ______ and a slow component to the ______.
- direction of spin
- opposite of spin
After stopping spinning, nystagmus has a horizontal fast component to the ______ and a slow component to the ______.
- opposite direction of spin
- toward the direction of spin
The vestibular apparatus includes
- The semicircular canals
- the vestibule
- utricle
- saccule
The Equilibrium pathway to the brain
- Hair cells in the vestibular apparatus activate the vestibular nerve
- impulses travel to either
- cerebellum, then/or
- vestibular nuclei (in brain stem)
- There, the info is integrated and sent to
- CN III
- CN IV
- CN VI
- CN XI
Dynamic Equilibrium is detected by the
- semicircular canals
- they detect angular acceleration in three planes
The ciliary muscle is controlled by the CN ____
CN III
The point of maximal visual acuity is the _________
fovea centralis
The blind spot in the eye is the
optic disc
Explain dynamic equilibrium
- Receptor: Cristae ampullaris
- found in semicircular canals
2.
- found in semicircular canals
What forms the floow of the scala media (cochlear duct); part of the organ of Corti?
The basilar membrane
Hair cells near the _____ are maximally stimulated by 20,000 Hz sound
Hair cells near the base of the cochlea
Hair cells near the _____ of the cochlea are maximally stimulated by 4,000 Hz sound
Hair cells near the apex of the cochlea
Within the cochlea, the structure has within it embedded hairs
Tectorial membrane
This membrane forms the roof of the scala media (cochlear duct)
Vestibular media
So that the tympanic membrane can vibrate normally, the ________ allows air pressure to become equal on either side.
eustachian tube
The primary function of the stapes is to
to transmit vibratory motion of the eardrum to the oval window.
Interpreting sound intensity (loudness) involves the
organ of Corti
Multple choice…The organ of Corti is
- A. located in the scala media
- B. responsible for hearing
- C. responsible for equilibrium
- D. located in the scala tympani
- E. two of the proceeding
- E. two of the proceeding
- A. located in the scala media
- B. responsible for hearing
In which component of the cochlea do sounds cause waves at a specific location (having the peak amplitude of a specific tone/frequency)
The basilar membrane
Nerves that contain parasympathetic fibers
- Brain stem
- CN III - occulomotor
- CN VII - facial
- CN IX - glossophryngeal
- CN X - vagus
- SC
- S2-S4
Nerves that contain preganglionic sympathetic fibers
- T1-L2
