Anatomy and Physiology XXVII

Question 1

To test the function of the inferior rectus muscle, how do you direct the patient to move his/her eye?

Answer 1

Have the patient try to look down from the abducted position (p.440)

Question 2

To test the function of the medial rectus muscle, how do you direct the patient to move his/her eye?

Answer 2

Have the patient try to look medially (nasally) (p.440)

Question 3

To test the function of the lateral rectus muscle, how do you direct the patient to move his/her eye?

Answer 3

Have the patient try to look laterally (temporally) (p.440)

Question 4

To test the function of the superior oblique muscle, how do you direct the patient to move his/her eye?

Answer 4

Have the patient try to look down from the adducted position (p.440)

Question 5

To test the function of the inferior oblique muscle, how do you direct the patient to move his/her eye?

Answer 5

Have the patient try to look upwards from adducted position (p.440)

Question 6

Generally, in which direction do the oblique muscles of the eye move the eye?

Answer 6

In the opposite direction (i.e. Superior moves eye downwards; inferior moves eye upwards) (p.440)

Question 7

How is miosis innervated?

Answer 7

Parasympathetic innervation (p.440)

Question 8

Describe the path of the first neuron involved in control of miosis.

Answer 8

CN III travels from the Edinger-Westphal nucleus to the ciliary ganglion (p.440)

Question 9

Describe the path of the second neuron involved in control of miosis.

Answer 9

Short ciliary nerves to pupillary sphincter muscles (p.440)

Question 10

How is mydriasis innervated?

Answer 10

Sympathetic innervation (p.440)

Question 11

Describe the path of the first neuron involved in control of mydriasis.

Answer 11

Hypothalamus –> ciliospinal centre of Budge C8-T2 (p.440)

Question 12

Describe the path of the second neuron involved in control of mydriasis.

Answer 12

Exit at T1 to superior cervical ganglion (which travels along the cervical sympathetic chain near the lung apex and subclavian vessels) (p.440)

Question 13

Describe the path of the third neuron involved in control of mydriasis.

Answer 13

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)

Question 14

Describe the pathway by which the pupillary light reflex functions.

Answer 14

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)

Question 15

What is the result of an intact pupillary light reflex?

Answer 15

Illumination of one eye results in bilateral pupillary constriction (p.440)

Question 16

What is a Marcus Gunn pupil?

Answer 16

An afferent pupillary defect results in decreased bilateral pupillary constriction when light is shone in affected eye relative to the unaffected eye (p.440)

Question 17

How do you test for a Marcus Gunn pupil?

Answer 17

Swinging flashlight test (p.440)

Question 18

Name two possible causes of an afferent pupillary defect.

Answer 18

Optic nerve damage, retinal detachment (p.440)

Question 19

Which component of CN III is primarily affected by vascular disease?

Answer 19

Motor component (p.441)

Question 20

How does vascular disease affecte the motor component of CN III?

Answer 20

Due to decreased diffusion of oxygen and nutrients to the interior fibers from compromised vasculature (p.441)

Question 21

What are signs of vascular disease induced impairments to CN III?

Answer 21

Motor impairment- down and out gaze (p.441)

Question 22

Where is the motor component of CN III in relation to the parasympathetic component?

Answer 22

Motor component is central; parasympathetic component is peripheral (p.441)

Question 23

What affects the parasympathetic component of CN III?

Answer 23

Compression (ex. Posterior communicating artery aneurysm, uncal herniation) (p.441)

Question 24

What are signs of compression induced impairments to CN III?

Answer 24

Diminished or absent pupillary light reflex (blown pupil) (p.441)

Question 25

What is retinal detachment?

Answer 25

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)