Vision
What is convergence insufficency
the eyes fail to turn inward properly when focusing on a close object, causing one or both eyes to drift outward
These descending motor pathways carry vestibular information from the brainstem to the spinal cord, helping maintain upright posture and adjust muscle activity in response to head movement.
What are vestibulospinal pathways?
This term describes the illusion of movement of oneself or the environment, and is a symptom rather than a diagnosis.
What is vertigo?
A lesion here, before the optic chiasm, causes monocular vision loss in one eye.
What is the optic nerve?
A person with this type of vision loss may repeatedly miss objects located on one side of space, distinct from unilateral neglect.
What is homonymous hemianopia (or visual field loss)?
Demonstration
Demonstration
Sacades, smooth pursuits, convergence/divergance,
This clinical test uses specific head positioning to help identify positional vertigo or BPPV.
What is the Dix-Hallpike test
The illusion that the visual environment is moving or bouncing.
May occur when vestibular dysfunction prevents adequate compensatory eye
movements during head movement
What is Oscillopsia
This type of visual field loss results from a lesion at the optic chiasm affecting the crossing nasal retinal fibers.
What is bitemporal hemianopia?
This type of vision supports safe mobility by detecting movement and providing awareness of the surrounding environment.
What is peripheral vision?
This neural pathway starts at vestibular receptors, travels through the vestibular branch of CN VIII to the vestibular nuclei, then connects to the nuclei of CN III, IV, and VI to produce compensatory eye movement.
What is the neural pathway underlying the vestibulo-ocular reflex (VOR)?
This treatment maneuver uses a sequence of head and body positions to guide displaced otoconia out of a semicircular canal and back toward the utricle.
What is the Epley maneuver?
This symptom describes ringing, buzzing, or another perceived sound with no external source, and appears alongside vertigo and hearing loss in one specific peripheral vestibular disorder.
What is tinnitus (seen in Ménière disease)?
This type of vision provides fine detail, supports reading and facial recognition, and relies on the central retina.
What is central vision?
What three sensory systems must work together for the CNS to maintain balance, none of which can do the job alone?
Vision, vestibular input, and somatosensation
Which cranial nerves control each of the six extraocular muscles, and which muscles does each one innervate?
CN III (medial rectus, superior rectus, inferior rectus, inferior oblique), CN IV (superior oblique), and CN VI (lateral rectus).
What is the Endolymph and what does it do?
During head rotation, this inner-ear fluid lags behind due to inertia, causing the cupula to bend and changing vestibular nerve firing.
Image 2
Image 2
The left visual field ultimately projects to this cerebral hemisphere.
What is the right hemisphere?
A patient with vestibular dysfunction has trouble reading street signs while walking and turning their head during mobility. This functional complaint stems from failure of this reflex.
What is the vestibulo-ocular reflex (VOR)?
Beyond the primary visual pathway to the cortex, optic tract fibers branch to three other structures for automatic visual responses. Name all three and what each one controls.
What are the pretectum (pupillary light reflex), the superior colliculus (reflexive orientation of eyes and head toward visual stimuli), and the hypothalamus/suprachiasmatic nucleus (circadian rhythm regulation in response to light)?
What do the Utricle and Saccule do respectfully?
Utricle
• Oriented primarily horizontally when upright
• Especially responsive to horizontal linear acceleration & head tilt
Saccule
• Oriented primarily vertically when upright
• Especially responsive to vertical linear acceleration
Image 1
Image 1
Image 3
Image 3
A patient shows increased unsteadiness only when their eyes are closed. Explain what this Romberg finding suggests, and name one system it could point to.
What is increased reliance on vision to compensate for another impaired sensory system, which could point to either proprioceptive/sensory or vestibular impairment?