Ocular Neurology 1,2&3 Flashcards
(26 cards)
What cranial nerve controls most of the eye’s movement?
Cranial Nerve III (Oculomotor nerve) controls most of the eye’s movement, including the superior rectus, medial rectus, inferior rectus, inferior oblique, and levator palpebrae superioris.
What are the key functions of Cranial Nerve III (Oculomotor nerve)?
Controls eye movements (medial rectus, superior rectus, inferior rectus, inferior oblique).
Controls pupil constriction (via parasympathetic fibers).
Lid elevation (via levator palpebrae superioris).
What are the symptoms of Oculomotor nerve (CN III) damage?
Ptosis (drooping eyelid) due to paralysis of levator palpebrae superioris.
Mydriasis (dilated pupil) due to loss of parasympathetic control.
Exotropia and hypotropia (eye turning outward and downward).
Difficulty with upward and downward gaze.
What cranial nerve controls the Superior Oblique muscle?
Cranial Nerve IV (Trochlear nerve) controls the Superior Oblique muscle, which is responsible for intorsion, depression, and abduction.
What is the result of damage to Trochlear nerve (CN IV)?
Damage to Trochlear nerve (CN IV) leads to vertical diplopia (double vision) and hypertropia (the affected eye being elevated), especially when the patient looks down.
What cranial nerve controls the Lateral Rectus muscle?
Cranial Nerve VI (Abducens nerve) controls the Lateral Rectus muscle, which is responsible for abduction (moving the eye outward).
What are the clinical signs of damage to Abducens nerve (CN VI)?
Eso tropia (eye turning inward) due to the loss of lateral rectus function.
Limited abduction: The affected eye cannot move laterally, causing horizontal diplopia (double vision when looking to the side).
What is the role of the Vestibulo-Ocular Reflex (VOR)?
The VOR helps stabilize vision by causing the eyes to move in the opposite direction of head movements, maintaining the foveal focus on objects even when the head is in motion.
How does VOR assist in vision during head movement?
The VOR maintains stable retinal images during head movement by generating compensatory eye movements in the opposite direction, ensuring steady vision even when the head turns.
What are the functions of the Frontal Eye Field (FEF)?
The Frontal Eye Field (FEF) controls saccadic eye movements (rapid shifts of focus between points), coordinating voluntary and reflexive eye movements, especially for attention and visual scanning.
What is the role of the Superior Colliculus in ocular movements?
The Superior Colliculus, located in the midbrain, is involved in initiating reflexive eye movements toward visual stimuli, particularly in the dorsal visual pathway.
What is Internuclear Ophthalmoplegia (INO), and what causes it?
Internuclear Ophthalmoplegia (INO) is a condition caused by damage to the Medial Longitudinal Fasciculus (MLF), resulting in impaired adduction (the ability of one eye to move towards the nose) in horizontal gaze.
What is nystagmus, and what are its types?
Nystagmus is an involuntary rhythmic oscillation of the eyes, classified into two types:
Pendular nystagmus: Symmetric eye movements.
Jerk nystagmus: One slow phase followed by a fast phase. It is often associated with gaze instability and visual disorders.
What is Bell’s Palsy, and how does it affect eye movements?
Bell’s Palsy is a condition where the facial nerve (CN VII) is paralyzed, causing ptosis, ectropion (lower eyelid turning outward), and inability to close the eyelid properly, which can lead to dry eyes or corneal damage.
How does Horner’s Syndrome affect the eye?
Horner’s Syndrome results from damage to the sympathetic pathway and is characterized by ptosis, miosis (constricted pupil), anhidrosis (lack of sweating), and enophthalmos (sunken eyeball).
What is the pathway of the Pupillary Light Reflex?
Afferent pathway: Light enters the eye, travels through the retina, optic nerve, and pretectal nucleus in the midbrain.
Efferent pathway: The Edinger-Westphal nucleus sends parasympathetic fibers via Cranial Nerve III to constrict the sphincter pupillae.
What is the function of the Medial Longitudinal Fasciculus (MLF)?
The MLF is a neural tract connecting the brainstem nuclei controlling the extraocular muscles, facilitating coordinated eye movements, particularly during conjugate eye movements.
How does Wernicke’s Hemianopic Pupil occur?
Wernicke’s Hemianopic Pupil occurs when there is damage to the optic tract, resulting in pupillary dysfunction where the light reflex is absent in one eye despite visual input.
What are the signs of Ocular Motor Nerve (CN III) palsy?
Oculomotor nerve (CN III) palsy results in ptosis, mydriasis (dilated pupil), and loss of eye movements (e.g., inability to move the eye upwards or inwards).
What are the roles of the Occipital Eye Field (OEF)?
The Occipital Eye Field (OEF) is responsible for smooth pursuit movements, allowing the eyes to follow a moving object smoothly and continuously.
What is conjugate gaze, and how is it controlled?
Conjugate gaze refers to the coordinated movement of both eyes in the same direction. It is controlled by the Frontal Eye Fields (FEF), Superior Colliculus, and brainstem nuclei.
How does Herpes Zoster Ophthalmicus affect ocular function?
Herpes Zoster Ophthalmicus results from the reactivation of the varicella-zoster virus in the ophthalmic division of the trigeminal nerve (CN V), leading to painful vesicular eruptions along the forehead and eyelid, affecting the cornea and eyelids.
What are the common causes of double vision (diplopia)?
Common causes of diplopia include:
Cranial nerve palsies (III, IV, VI).
Strabismus (misalignment of the eyes).
Internuclear ophthalmoplegia (INO).
Myasthenia Gravis (neuromuscular junction disorder).
: What are the common ocular manifestations of Multiple Sclerosis (MS)?
Multiple Sclerosis (MS) can cause optic neuritis, internuclear ophthalmoplegia (INO), and nystagmus due to demyelination of the optic nerve and brainstem pathways.
