Orbit and Contents

Question 1

what is the function of the lacrimal gland and nasolacrimal duct?

Answer 1

lacrimal gland–allows tears to be secreted into the conjunctival sac
nasolacrimal duct–passage for tears that opens into the nasal cavity

Question 2

what is the function of the superior tarsal muscle?

Answer 2

an involuntary, smooth muscle responsible for the “tone” of the eyelid

Question 3

what is the innervation of the superior tarsal muscle? what can defect this muscle?

Answer 3

sympathetic fibers; damage to the superior cervical ganglion (horner’s)

Question 4

what is the function of the tarsal gland?

Answer 4

secrete fatty substance keeping the lids from sticking together when closed

Question 5

what is a sty?

Answer 5

blocked ciliary gland

Question 6

list the innervation of all the extraocular muscles

Answer 6

lacteral rectus–CN VI; superior oblique–CN IV; all others are innervated by CN III

Question 7

describe the action of the medial rectus, lateral rectus, inferior and superior rectus on the direction of the iris.

Answer 7

medial–adduction
lateral–abduction
inferior–medially and downward
superior–medially and upward

Question 8

describe the action of the superior and inferior oblique on the direction of the iris.

Answer 8

superior– laterally and downward

inferior–laterally and upward

Question 9

how would you specifically test each extraocular muscle for integrity?

Answer 9

Ask the patient (while gazing in the visual axis) to look in the directions of their actions.
LR--abduction
MR--adduction
SR--medially and upward
IR--medially and downward
SO--laterally and downward
IO--laterally and upward

Question 10

How would a lesion of CN VI appear?

Answer 10

paralysis of LR and the inability to abduct the eye

Question 11

How would a lesion of CN IV appear?

Answer 11

IO unopposed; intortion not possible, so eyeball is extorted, which results in diplopia (double vision)

Question 12

How would a lesion of CN III appear?

Answer 12

No adduction is possible among other movements

Question 13

What is extorsion and intorsion? what is the function of these movements?

Answer 13

movements involving rotation of the eye ball around its visual axis (with eyeball not in its LOP); to keep image viewed level regardless of the angle of tilt of the head

Question 14

Describe extorsion and list the muscle that is responsible for this movement

Answer 14

rotation toward nose from below–IO

Question 15

Describe intorsion and list the muscle that is responsible for this movement.

Answer 15

rotation toward nose from above–SO

Question 16

which layer of the eye contains the photoreceptor cells?

Answer 16

retinal layer

Question 17

what is the optic disc?

Answer 17

blind spot; circular area posteriorly where the optic nerve exits the eye

Question 18

why would you stay away from the fovea centralis when using a laser to reattach the retina?

Answer 18

its is the most acute area of vision

Question 19

what is glaucoma? what is the anatomical development of this disorder?

Answer 19

an increase in pressure of the aqueous humor in the ANTERIOR chamber of the eye; AH is constantly produced in the ciliary body. it cannot be drained into the venous sinus at the iridial angle due to the compression of these thin-walled vessels as a result of the increased pressure exerted by the high amount of AH in the chamber.

Question 20

how does the mechanism of accommodation work? near and distant vision?

Answer 20

the ciliary m. contracts circularly. for close vision, the lens must be thicker to allow greater refraction of light required for viewing close objects. parasympathetic innervation constricts the pupil for close vision via CN III. As the iris constricts, the ciliary bodies come closer together allowing the suspensory ligaments of the lens to become lax. This allows the lens to bugle outward and thicken. distant vision is the opposite–pupil dilates, ciliary bodies become farther apart, lens thins out.