Anatomy and Physiology XXVII Flashcards
To test the function of the inferior rectus muscle, how do you direct the patient to move his/her eye?
Have the patient try to look down from the abducted position (p.440)
To test the function of the medial rectus muscle, how do you direct the patient to move his/her eye?
Have the patient try to look medially (nasally) (p.440)
To test the function of the lateral rectus muscle, how do you direct the patient to move his/her eye?
Have the patient try to look laterally (temporally) (p.440)
To test the function of the superior oblique muscle, how do you direct the patient to move his/her eye?
Have the patient try to look down from the adducted position (p.440)
To test the function of the inferior oblique muscle, how do you direct the patient to move his/her eye?
Have the patient try to look upwards from adducted position (p.440)
Generally, in which direction do the oblique muscles of the eye move the eye?
In the opposite direction (i.e. Superior moves eye downwards; inferior moves eye upwards) (p.440)
How is miosis innervated?
Parasympathetic innervation (p.440)
Describe the path of the first neuron involved in control of miosis.
CN III travels from the Edinger-Westphal nucleus to the ciliary ganglion (p.440)
Describe the path of the second neuron involved in control of miosis.
Short ciliary nerves to pupillary sphincter muscles (p.440)
How is mydriasis innervated?
Sympathetic innervation (p.440)
Describe the path of the first neuron involved in control of mydriasis.
Hypothalamus –> ciliospinal centre of Budge C8-T2 (p.440)
Describe the path of the second neuron involved in control of mydriasis.
Exit at T1 to superior cervical ganglion (which travels along the cervical sympathetic chain near the lung apex and subclavian vessels) (p.440)
Describe the path of the third neuron involved in control of mydriasis.
Plexus along the internal carotid travels through the cavernous sinus and enters the orbit as the long ciliary nerve to pupillary dilator muscles (p.440)
Describe the pathway by which the pupillary light reflex functions.
Light in either retina sends a signal via CN II to the pretectal nuclei in the midbrain that activates bilateral Edinger-Westphal nuclei. Pupils contract bilaterally via consentual reflex (p.440)
What is the result of an intact pupillary light reflex?
Illumination of one eye results in bilateral pupillary constriction (p.440)
What is a Marcus Gunn pupil?
An afferent pupillary defect results in decreased bilateral pupillary constriction when light is shone in affected eye relative to the unaffected eye (p.440)
How do you test for a Marcus Gunn pupil?
Swinging flashlight test (p.440)
Name two possible causes of an afferent pupillary defect.
Optic nerve damage, retinal detachment (p.440)
Which component of CN III is primarily affected by vascular disease?
Motor component (p.441)
How does vascular disease affecte the motor component of CN III?
Due to decreased diffusion of oxygen and nutrients to the interior fibers from compromised vasculature (p.441)
What are signs of vascular disease induced impairments to CN III?
Motor impairment- down and out gaze (p.441)
Where is the motor component of CN III in relation to the parasympathetic component?
Motor component is central; parasympathetic component is peripheral (p.441)
What affects the parasympathetic component of CN III?
Compression (ex. Posterior communicating artery aneurysm, uncal herniation) (p.441)
What are signs of compression induced impairments to CN III?
Diminished or absent pupillary light reflex (blown pupil) (p.441)
What is retinal detachment?
Separation of the neurosensory layer of the retina (photoreceptor layer with rods and cones) from the outermost pigmented epithelium which normally shields excess light and supports the retina (p.441)
