Flashcards in this deck (162)

• Which structures form the otolith organs and semicircular canals of the vestibular apparatus?

  • Utricle
  • Saccule
  • Semicircular canals (anterior, lateral, posterior)
• What cellular elements transduce head motion in the vestibular system and how are they arranged?

  • Hair cells with stereocilia and a kinocilium that bend against supporting structures (cupula or otolithic membrane)
• How does directional deflection of hair cell stereocilia affect afferent firing?

  • Deflection toward kinocilium excites (increases firing); away from kinocilium inhibits (decreases firing)
• What are typical vestibular afferent spike rates for excitation, resting, and inhibition as shown?

  • Excitation: 160 spikes/sec
  • Resting: 90 spikes/sec
  • Inhibition: 20 spikes/sec
• Which vestibulospinal tracts mediate posture and what are their primary target levels?

  • Lateral vestibulospinal tract: all spinal levels (posture)
  • Medial vestibulospinal tract: cervical levels (head/neck posture)
• Name the three main postural balance strategies listed for maintaining balance.

  • Ankle strategy
  • Hip strategy
  • Stepping strategy
• Which cerebellar subdivision is specifically associated with vestibular function?

  • Vestibulocerebellum
• Which structures make up the main sensory organs of the inner ear for vestibular function?

  • Semicircular canals (SCC)
  • Utricle
  • Saccule
• What is the core mechanism by which vestibular hair cells convey head motion to the brain?

  Hair cell deflection leads to receptor transduction that alters afferent firing rate
• What is the vestibulo-ocular reflex (VOR) key pathway and its ideal gain?

  • 3-neuron pathway
  • Gain = 1
• Name the vestibulospinal pathways involved in postural control.

  • Vestibulospinal reflex (VSR)
  • Vestibulocollic reflex (VCR)
• How does the cerebellum contribute to vestibular function?

  By mediating adaptation and sensory reweighting
• What is the difference between feedforward and feedback control of balance?

  • Feedforward (anticipatory): prepares movements before disturbance
  • Feedback (reactive): responds to disturbance after it occurs
• What two basic questions does the vestibular system ask?

  • Which way is up?
  • Where am I?
• What are the main functions of the vestibular system?

  • Postural Control
  • Gaze Stabilization
  • Head Position
  • Perception of self motion
  • Spatial Orientation
• Which structure is not considered part of the vestibular apparatus?

  • Cochlear
• What are the main components of the vestibular system?

  • Peripheral Sensors
  • Central Processors
  • Motor Output
• What are the three main anatomical divisions of the ear?

  • Outer ear
  • Middle ear
  • Inner ear
• Which three small bones (ossicles) are listed in the middle ear?

  • Malleus
  • Incus
  • Stapes
• Which inner ear sensory structures are named in the diagram?

  • Cochlear
  • Semicircular canals
• Which nerves are labeled near the ear in the diagram?

  • Vestibular nerve
  • Facial nerve
  • Auditory nerve
• What type of receptors are found in the semicircular canals and where are they located?

  • Mechanoreceptors
  • Ampulla
• Where are the semicircular ducts located?

  Inside the semicircular canals
• Name the three semicircular canals.

  • Anterior
  • Posterior
  • Lateral
• Where are the cristae ampullares located?

  In the membranous ampullae
• Where is the utricle located?

  In the vestibule
• Where is the saccule located?

  In the vestibule
• What structure occupies the oval window?

  The stapes
• Which nerves are listed alongside the temporal bone?

  • Facial nerve
  • Vestibular nerve
  • Cochlear nerve
• Where is the cochlear duct located and what organ does it contain?

  The cochlear duct is in the cochlea and contains the spiral organ (of Corti)
• What are the vestibular ganglia named in the list?

  • Superior vestibular ganglion
  • Inferior vestibular ganglion
• How is the membranous labyrinth positioned relative to the bony labyrinth?

  The membranous labyrinth is contained within the bony labyrinth
• Which window of the inner ear is named besides the oval window?

  The round window
• What sensory epithelia are named that detect linear acceleration and head position?

  The maculae
• What do the semicircular canals detect in the vestibular system?

  Angular acceleration
• What do the otolith organs detect in the vestibular system?

  • Linear acceleration
  • Gravitational pull
• How many semicircular canals (SCC) are there and what are their names?

  • Three
  • Anterior
  • Posterior
  • Horizontal (lateral)
• What is the spatial arrangement of the three semicircular canals?

  The three canals are at right angles to each other.
• What sensory modality do the semicircular canals detect?

  They detect angular head movements.
• How do the semicircular canals function in pairs and what are their motor outputs?

  Canals function in coplanar pairs (push/pull); motor outputs generate compensatory eye movements and postural movements.
• Name the three semicircular ducts of the inner ear.

  • Anterior
  • Lateral
  • Posterior
• List key structures found in a semicircular ampulla.

  • Cupula
  • Hair cells
  • Supporting cells
  • Sensory nerve fibers
  • Crista ampullaris
• During head rotation, why does endolymph produce a force on the cupula?

  Endolymph lags behind due to inertia, producing relative fluid motion that pushes on the cupula.
• What is the immediate effect of the cupula being pushed over?

  The cupula is pushed over and stimulates the hair cells.
• How does cupula displacement change hair cell activity?

  Displacement of the cupula deflects the hair bundles (stereocilia) in the direction of the relative fluid motion in the canal.
• How many stereocilia are typically found on a hair cell?

  40 to 70
• What morphological feature do stereocilia provide to a hair cell?

  They give each hair cell a morphological axis of polarity
• What main categories of ion channels are listed for hair cells?

  • Leakage
  • Gated
• Which gated channel types are listed for hair cells?

  • Mechanical
  • Ligand (NT)
  • Voltage-gated
• How many kinocilia are indicated on a hair cell?

  A single kinocilium
• Which ion is mentioned in the notes related to hair cell function?

  Ca+
• What are the two channel states shown in the diagram of stereocilia?

  • Open
  • Close
• What is produced in hair cells when stereocilia are bent?

  • Local or graded potential
• Which neurotransmitters are listed in the notes?

  • Aspartate
  • Glutamate
• What firing rates (spikes/sec) are shown in the diagram?

  • 160 spikes/sec
  • 90 spikes/sec
  • 20 spikes/sec
• What are vestibular otoliths?

  • Membranous sacs that house equilibrium receptors (maculae)
• What static function do otoliths perform?

  • Respond to gravity and changes in head position (static equilibrium)
• What dynamic function do otoliths perform?

  • Detect linear acceleration (dynamic equilibrium)
• What crystals are contained in the otoliths?

  • Calcium carbonate crystals
• Which otolith detects horizontal acceleration and which detects vertical?

  • Utricle: detects horizontal acceleration
  • Saccule: detects vertical acceleration
• Which vestibular organs are responsible for perception of linear acceleration and head position?

  • Utricle
  • Saccule
• Name the main anatomical components shown in a macula of the otolith organs.

  • Macula utriculi / Macula sacculi
  • Hair cell
  • Supporting cell
  • Otoliths
  • Otolithic membrane
  • Vestibular nerve
• What mechanically causes stereocilia of hair cells in the macula to bend?

  • Gravitational force causes the otolithic membrane to sag, which bends the stereocilia of hair cells
• Which inner ear structures contain a macula?

  • Utricle
  • Saccule
• What are otolith (ear stone) crystals composed of?

  • Calcium carbonate
• Which sensory cells transduce movement of the otoliths?

  • Hair cells
• Which two movements can vestibular otoliths not differentiate between?

  • Forward head tilt
  • Linear acceleration
• What is the primary function of the Vestibular Ocular Reflex (VOR)?

  • Maintains stable vision during head movements
• What does the Vestibular Spinal Reflex (VSR) do?

  • Group of reflexes that stabilize the body
• What is the action of the Vestibulocollic Reflex (VCR)?

  • Acts on neck musculature to stabilize the head
• Which neural structure carries vestibular sensory input from the inner ear?

  • Vestibular branch of vestibulocochlear (VIII) nerve
• Name the labelled pathway that connects vestibular outputs to the spinal cord for postural control.

  • Vestibulospinal tract (labelled B - VSR) connects to the spinal cord
• What is the vestibular ocular reflex (VOR) primarily stimulated by?

  Head movement
• What primary function does the VOR serve?

  Maintaining focus on a target during head movement (gaze stability)
• How do VOR-induced eye movements relate to head movements in direction and magnitude?

  Eye movements are equal in magnitude/speed but opposite in direction to head movements
• What is the VOR gain and give the numeric example provided?

  Gain = 1 (eye speed/head speed); example: \(120/120=1\)
• In the horizontal semicircular canal, what does 'ampullo-petal' fluid flow mean for hair cell response?

  Ampullo-petal (towards the ampulla) causes excitation of the hair cells
• What effect does 'ampullo-fugal' (away from the ampulla) fluid flow have on hair cell firing?

  Ampullo-fugal (away from the ampulla) causes inhibition and a decrease in firing
• According to the diagram, which response is shown for the left and right horizontal semicircular canals?

  • Left horizontal SCC: ampullo-petal → excitation
  • Right horizontal SCC: ampullo-fugal → inhibition
• How many neurons are in the basic Vestibulo-Ocular Reflex (VOR) neural pathway?

  • 3 neurons
• Describe the three sequential connections in the VOR pathway.

  • 1. Inner ear to vestibular nuclei
  • 2. Vestibular nuclei to extraocular nuclei
  • 3. Extraocular nuclei to effector muscle
• During a head turn to the left, what is happening at the right horizontal canal?

  • Endolymph flows right in the right horizontal canal
• Where are the vestibular nuclei located?

  • Pons-medullary junction
• What color is used to represent motor (descending/efferent) pathways in the diagram?

  • Red
• Which tracts are listed under pyramidal (motor) tracts?

  • Lateral corticospinal tract
  • Anterior corticospinal tract
• Which tracts are listed under extrapyramidal (motor) tracts?

  • Rubrospinal tract
  • Reticulospinal tracts
  • Olivospinal tract
  • Vestibulospinal tract
• Which fiber bundles compose the Dorsal Column Medial Lemniscus system?

  • Gracile fasciculus
  • Cuneate fasciculus
• What tracts make up the Anterolateral System and the Spinocerebellar Tracts?

  • Anterolateral System: Lateral spinothalamic tract, Anterior spinothalamic tract, Spino-olivary fibers
  • Spinocerebellar Tracts: Posterior spinocerebellar tract, Anterior spinocerebellar tract
• Which afferent inputs contribute to the Vestibular Spinal Reflex (VSR)?

  • Otoliths
  • Semicircular canals (SCC) (to a lesser degree)
• Through which tract do vestibular afferents generate postural responses?

  • Lateral Vestibular Spinal Tract
• What are the primary output targets of the Vestibular Spinal Reflex?

  • Lower extremity (LE) skeletal muscles
  • Trunk muscles
• What is the pattern of muscle activity produced by the VSR?

  • Complex pattern of excitation and inhibition
• What object is described in the provided description?

  • A wooden baseball bat with black grip and knob, resting on a white surface
• Which cranial nerves are listed as involved in the vestibular ocular reflex?

  • Cranial nerve 8 (vestibulocochlear n)\n- Cranial nerve 11 (accessory n)
• Which sensory organ is listed as controlling the vestibular ocular reflex?

  • **The otoliths
• What primary function of the vestibular ocular reflex is described regarding gaze?

  • **Keeps your gaze stable when you are in motion
• What is the role of the medial vestibulospinal tract in the vestibulocollic reflex (VCR)?

  • Coordinates head position with the position of the body in space
  • Mediates the vestibulocollic reflex
• Which muscles does the motor arm of the vestibulocollic reflex activate?

  • Postural muscles (via anterior horn cells)
• What is the primary function of the vestibular nucleus?

  • The vestibular nucleus is the primary processor that implements fast direct connections
• What role does the cerebellum play in vestibular processing?

  • The cerebellum is an adaptive processor that monitors vestibular performance and readjusts if necessary
• What are the major projection targets of the vestibular nuclei?

  • Extraocular muscles via the medial longitudinal fasciculus (MLF)
  • Vestibulospinal tracts
  • Vestibulothalamocortical pathway
  • Vestibulocerebellar pathways
  • Vestibuloreticular pathways
• Name the four main vestibular nuclei.

  • Lateral Vestibular Nucleus (Dieter's nucleus)
  • Superior Vestibular Nucleus
  • Inferior Vestibular Nucleus
  • Medial Vestibular Nucleus
• What is another name for the Lateral Vestibular Nucleus?

  • Dieter's nucleus
• Which three reflex/pathway abbreviations are associated with the vestibular nuclei?

  • VSR
  • VOR
  • VCR
• Where do the vestibular nuclei project for feedback control?

  • To the cerebellum for feedback
• To which system do the vestibular nuclei project for arousal and autonomic functions?

  • To the reticular formation for arousal and ANS
• Which inner ear receptors are listed for the semicircular canals, utricle, and saccule?

  • Semicircular canals: ampullae
  • Utricle: maculae
  • Saccule: maculae
• Name the four vestibular nuclei abbreviations shown.

  • SVN
  • LVN
  • IVN
  • MVN
• What key connection is noted for the vestibulo-ocular reflex (VOR)?

  • VOR: contralateral CN 6 via ascending MLF fibers
• What is the origin and laterality of the lateral vestibulospinal tract (VSR)?

  • Origin: lateral vestibular nucleus (VSR)
  • Laterality: unilateral (lateral VST)
• What is the origin and laterality of the medial vestibulospinal tract (VCR)?

  • Origin: medial vestibular nucleus (VCR)
  • Laterality: bilateral (medial VST)
• Where do MLF descending fibers project for head position adjustment?

  • MLF descending fibers: to cervical spinal cord for adjustment of head position
• Which two central structures receive vestibular projections as labeled?

  • Thalamus
  • Cerebellum
• Which cerebellar areas were listed as options for involvement in postural control and eye stabilization?

  • Cerebrocerebellum (lateral hemispheres)
  • Intermediate hemispheres of Spinocerebellum
  • Inferior cerebellar peduncles
  • Flocculonodular lobe
• What is one primary role of the cerebellum in posture?

  • Balance/Postural control
• What cerebellar function supports smooth execution of movement?

  • Coordination of movement
• How does the cerebellum modulate the vestibulo-ocular reflex (VOR)?

  • Recalibrates neural firing rate
• What is the cerebellum's role in motor adaptation or motor learning?

  • Compensates for errors by comparing intention with performance (error detector)
• What are the three functional divisions of the cerebellum and their main functions?

  • Spinocerebellum: Execution - motor
  • Cerebrocerebellum: Planning - motor
  • Vestibulocerebellum: Balance
• What are the primary inputs to the vestibular nuclei?

  • Labyrinth (inner ear) input
  • Cerebellum
• Which cranial nerve division provides vestibular afferents to the vestibular nuclei?

  • Vestibular division of cranial nerve VIII
• Through which pathway do the vestibular nuclei connect to cranial nerves III, IV, and VI?

  • Medial longitudinal fasciculus (MLF)
• What vestibular tract connects the vestibular nuclei to the spinal cord at all levels and is associated with posture?

  • Lateral vestibulospinal tract (all levels; posture)
• Which vestibulospinal tract targets cervical levels and is associated with posture?

  • Medial vestibulospinal tract (cervical levels = posture)
• What higher pathways do vestibular nuclei use to reach conscious perception?

  • Thalamus to cerebral cortex
• What is orientation in postural control?

  Positioning of body segments with respect to one another and environment (Verticality).
• What is stability in postural control?

  Active resistance to external forces acting on the body.
• How should the shoulders be positioned for mirror-image bifunctionality?

  • Even, rolled back
• How should the hips be positioned for mirror-image bifunctionality?

  • Level and untilted
• How should the knees and feet be aligned in the body schema diagram?

  • Painting straight ahead
• Which directions are indicated for load bearing in the body schema balance?

  • Back
  • Forward
• What relationship indicates mechanical stability in a standing body?

  Center of mass positioned over the base of support
• Balance emerges from the interaction of which three elements?

  • Individual
  • Postural Tasks
  • Environment
• What is steady state postural control?

  Maintaining balance when sitting, kneeling, or standing quietly.
• What is anticipatory (proactive) postural control?

  When the CNS forms a representation of the actions needed to accomplish a task.
• What is reactive postural control?

  Movement strategies used to recover stability from an unexpected perturbation.
• What effect can voluntary movements have on posture and equilibrium?

  Voluntary movements can destabilize postural orientation and equilibrium.
• How does the nervous system maintain postural alignment when planning voluntary movement?

  The nervous system has advanced knowledge of movement effects on posture and activates anticipatory postural adjustments to preserve alignment and stability.
• What are the main inner ear structures involved in vestibular sensing?

  • Semicircular canals (SCC)
  • Utricle
  • Saccule
• How do vestibular hair cells convert head movement into neural signals?

  • Hair cell transduction converts mechanical deflection into changes in afferent firing
• What is the basic organization of the vestibulo-ocular reflex (VOR)?

  • VOR is a 3-neuron pathway with a gain of 1
• Which descending tracts mediate vestibular control of posture?

  • Vestibulospinal tracts: vestibulospinal reflex (VSR) and vestibulocollic reflex (VCR)
• What roles do the cerebellum play in vestibular function?

  • Cerebellar adaptation and sensory reweighting
• What are the two main strategies for postural control?

  • Anticipatory strategies
  • Reactive strategies
• What does the provided diagram illustrate about anticipatory muscle activity?

  • A person holding a handle against a wall with EMG traces showing anticipatory activation of biceps and gastrocnemius
• What are reactive balance strategies?

  • In-place strategies (ankle & hip)
  • Change of base of support (stepping)
• What are in-place strategies for reactive balance?

  • Ankle strategy
  • Hip strategy
• What is the change of base of support reactive strategy?

  • Stepping strategy
• Why are multiple senses required for accurate body position (postural) control?

  Because sensory information can be redundant and a single modality may be ambiguous, so multiple senses provide complementary information.
• What is a limitation of vision for sensing body movement?

  Vision cannot differentiate between endogenic (self-generated) and exogenic (external) movement.
• What ambiguity exists in vestibular sensory information about head/body orientation?

  The vestibular system cannot differentiate between a forward head tilt and the entire body tilted forward.
• What is 'Sensory Integration'?

  The process of integrating sensory modalities to form an internal representation of the body.
• What is 'Sensory Reweighting'?

  The CNS's ability to modify how it uses sensory information.
• When does sensory reweighting occur?

  During the process of learning new motor skills.
• What does it mean that balance control is a 'whole-brain phenomenon'?

  • Balance control involves multiple brain regions working together rather than a single area
• What postural control roles are attributed to the brainstem?

  • Regulate reactive postural synergies
  • Regulate anticipatory postural control
  • Process vestibular inputs for postural control
• What is the role of the basal ganglia in postural control?

  • Quickly control muscle patterns in response to changing task and environment
• How does the cerebellum contribute to postural control?

  • Modify postural muscle response amplitudes based on experience (example: car brakes)
• What role of the cerebral cortex is explicitly mentioned in the notes?

  • Attention
• What is dual-task interference as defined in the notes?

  Competition for available attentional resources that may cause decreased performance in one or both tasks
• Which brain system is linked to emotions in the notes?

  • Limbic system
• What is described as key in life?

  • Balance