Week 3 Flashcards
What are the 2 otolith organs?
- Utricle
2. Saccule
What are the names of the 3 semi-circular canals
- Horizontal (Lateral)
- Anterior (Superior)
- Posterior
Semi-Circular Canals sense what type of acceleration?
Angular Acceleration - moving head to side to side
Otolith Organs sense what type of acceleration? Give 2 examples
Linear acceleration
- Changing head position from laying to standing
- Gravity change, riding on elevator
What are the two structures inside the SCC?
Ampula and Cupula
What structure contains the hair cells?
Cupula
What is present in the utricle and saccule that contain crystals and allow one to judge gravity?
Macula
WIT: A swelling at the entrance of each Semi-circular canal? What does it contain?
Ampula, contains a cupula
What specific feature causes the SCCs to only be responsive to angular acceleration?
The cupula and endolymph are the same density
Stimulation from sterocilia to kinocilia = ?
Excitatory,
- depolarization causing increased firing of VN
Stimulation from kinocilia to sterocilia = ?
inhibitory
-hyperpolarization, decreased firing of CN
What is the 3 neuron arc for horizontal VOR?
- SCC
- Vestibular Nuclei
- OMN (abducens + oculomoter)
The head velocity signal is generated by what?
SCC
What are the neural integrators for horizontal conjugate eye movements?
MCN
NPH
The utricle presents on what plane?
Horizontal Plane
The saccule presents on what plane?
Vertical Plane
The presence of what increases the density of the gelatinous material of the macula, allowing for gravitational changes to be sensed?
Calcium Carbonate Crystals (called Otoconia)
Translational VOR is induced when stimulated by what otolith?
Utricle
Ocular Counter-Rolling is indiced by the stimulation by which otolith?
Saccule
What specific sensory structures are being activated when riding in an elevator?
t-VOR, utricle
What is themost common cause of dizziness? What is this called?
When calcium carbonate crystals from utricle migrate into the posterior SCC
BPPV = Benign Paroxysmal Positional Vertigo
Kinocilia of the Utricle are oriented where?
Towards the striola in the center
Kinocilia of the Saccule are oriented where?
Away from the striola/center,
What are the 3 parts of the 8th cranial nerve?
- Cochlear
- Inferior vestibular
- Superior vestibular
The inferior vestibular portion of the 8th CN contains what 2 things?
Saccule
Posterior SCC
The superior vestibular portion of the 8th CN contains what 3 things?
Utricle
Horizontal and Anterior SCC
What are the 4 subdivisions of the vestibular nuclei?
- Medial
- Lateral
- Descending/Inferior
- Superior
Intrinsic connections within the vestibular nuclei are connections between subdivisions. They do not cross the ____.
midline
Commissural connections within the VN do cross the ___
midline
This is the largest vestibular nucleus. Large concentration of vestibular ocular neurons.
Medial vestibular nucleus.
This vestibular nucleus contains incoming projections from the vestibular nerve.
Lateral VN
This VN contains commissural fiber connections through the midline of the structure. It also has vestibular ocular projections.
Superior VN
This VN has fiber bundles from the cerebellum of the inferior olive
Descending/inferior VN
Who’s law: head motion in one direction causes endolymph in the SCC to move in the opposite direction
Ewalds Second Law
What type of head movement dominates head velocity?
VOR dominant primary
Postural control need what 3 things?
- Vestibular
- Visual
- Somatosensory (info coming from bottom of feet)
What are the 3 major functions of the vestibulospinal reflexes?
- Maintain posture
- Produce kinetic contractions of muscles
- Maintain muscular tone
What are the 3 vestibular nuclei of the spinal tract?
- Medial VS Tract
- Lateral VS Tract
- Reticulospinal Tract
The pyramidal system of the cerebral Cortex does what 3 things?
- Fine motor skills
- Volitional movements
- Control over upper extremities more than lower
The extrapyramidal system of the cerebral Cortex does what 2 things?
- Large reflexive movements
2. Postural adjustments.
The purpose of the myotic reflex system is to regulate muscle force and to maintain stability around a joint. It’s triggered by external stimuli. Shows fixed behavior. What controls this reflex?
Spinal Cord
The functional stretch response coordinates limb and trunk movements around a joint; balances the 1st line of defense; Highly adaptable. What controls this response?
Brainstem and (sub)cortical
Volitional movements are self generated, learned, purposeful movements. What controls this movement ?
Cortical.
- also has contributions from the vestibular, visual, and somatosensory systems
Where do mossy fibers arise from?
From brainstem and spinal cord
Where do climbing fibers arise from? What do they create?
Arise from inferior olive
Creates powerful excitatory response from purkinje cells
The flocculonodular system is part of the cerebellum. What is its function?
Helps in recovery and compensation
