anatomy

Question 1

action + innervation of lateral rectus muscle

Answer 1

ONLY aBduct eyeball

CN VI (abducent)

–> brings line of gaze into same plane as superior rectus + inferior rectus

Question 2

action + innervation of superior rectus muscle

Answer 2

when in aBduction, can ONLY elevate

CN III (oculomotor)

Question 3

action + innervation of inferior rectus

Answer 3

when in abduction, can ONLY depress

CN III (oculomotor)

Question 4

action + innervation of medial rectus muscle

Answer 4

aDduct only

CN III (oculomotor)

–> same plane as superior + inferior obliques

Question 5

action + innervation of internal oblique muscle

Answer 5

when in aDduction can only elevate

CN III (oculomotor)

Question 6

action + innervation of superior oblique

Answer 6

when in aDduction, only depress

CN IV (trochlear)

Question 7

innervation of the extraocular muscles

Answer 7

LR6 SO4 AO3

lateral rectus CNVI (abducent)
superior oblique CNIV (trochlear)
all others CNIII (oculomotor)

Question 8

sympathetic reflexes of the eye

Answer 8

opens eyes wider - more light
focus on far objects
emotional lacrimation

Question 9

parasympathetic reflexes of the eye

Answer 9

less light in
focus on near objects

reflex lacrmation - wash away stimulant foreign body

Question 10

sensory + motor limbs of the corneal reflex (blink)

Answer 10

sensory = CNV1 (cornea, V1, trigeminal ganglion, pons)

motor = CN VII (facial –> orbicularis oculi)

Question 11

which nerves are being tested in the corneal reflex (blink)

Answer 11

facial + trigeminal (ophthalimic)

V1 = sensory/afferent
facial = mottor/efferent

Question 12

what muscle is responsible for opening eyes wider? how is this innervated?

Answer 12

levator palpebrae superioris
skeletal muscle PLUS smooth muscle (Muellers muscle)

SYMMPATHETIC innervation

Question 13

the tendon of which extraocularmuscle passes through the trochlea?

Answer 13

superior oblique

Question 14

what is the somatic motor innervation of the lateral rectus muscle?

Answer 14

abducens

Question 15

what is the action of the levator palpebrae superioris?

Answer 15

elevate upper eyelid

Question 16

where to sympathetics leave spinal cord

Answer 16

T1-L2`

Question 17

postsynaptic sympathetic fibres reach the orbit by travelling on the surface of which artery?

Answer 17

ophthalamic

Question 18

a parasympathetic ganglia thats associated with the eyeball

Answer 18

cilliary

Question 19

the ciliary ganglion is associated with which cranial nerve?

Answer 19

CN III oculomotor

Question 20

what muscle is responsible for parasympathetic response of constricting pupil?

Answer 20

sphincter pupillae

dilator pupillae (radially arranged) pulls on sphincter pupillae to stretch + widen pupil

Question 21

class of drugs used to induce pupil dilation

Answer 21

mydriatic

Question 22

special sensory + motor CNs responsible for the pupillary light reflex

Answer 22

special sensory (afferent) = ipsilateral CN II

motor (efferent) = CN III

Question 23

normal response to pupillary light reflex

Answer 23

constriction in stimulated eye (direct)

a consensual constriction will also occur in non stimulated eye

Question 24

location of cell bodies of parasympathetic axons of CN III

Answer 24

Edinger-Westphal (EW) nucleus

involved in the pupillary light reflex pathway, synapses with ciliary ganglion via CN III

Question 25

which muscle controls the shape of the lens?

Answer 25

ciliary muscle
smooth muscle like a sphincter around circumference
muscular and vascular

Question 26

what effect does relaxation of the ciliary muscle have on the vision of the eye? shape of the lens?

Answer 26

ciliary muscle relaxes in “far vision”
–> ligament TIGHTENS + lens FLATTENS to focus on object in distance

NO parasympathetics

Question 27

what effect does contraction of the ciliary muscle have on the vision of the eye? shape of the lens?

Answer 27

ciliary muscle contracts in “near vision”
–> ligament contracts+ lens becomes MORE SPHERICAL to focus on near objects

PARASYMPATHETIC

Question 28

when is the lens accommodation reflex used?

Answer 28

in response to “near”

Question 29

3 components of the lens accommodation reflex?

Answer 29

1. bilateral pupilllary constriction - parasympathetic constriction of sphincter pupillae
2. convergence of both eyes towards midline - medial rectus
3. bilateral relaxation of lens - contraction of ciliary muscles (more spherical)

Question 30

CN responsible for lens accommodation reflex

Answer 30

CN III

Question 31

3 reflexes of lacrimation

Answer 31

basal tears - corneal health

reflex tears - mechanical or chemical stimulation

emotional tears

Question 32

enzyme contained in basal tears

Answer 32

lysozyme - hydrolyses bacterial cell walls

Question 33

CN involved in reflex tears

Answer 33

afferent = CN V1 from cornea/conjunctiva

efferent = parasympathetic axons originating from CN VII

Question 34

splanchnic nerves

Answer 34

supplies sympathetic innervation to organs

Question 35

pathways of presynaptic SYMPATHETIC axons from CNS to head + neck

Answer 35

exit spinl cord in T1
ascend within sympathetic chain
synapse in SUPERIOR CERVICAL SYMPATHETIC GANGLION

Question 36

pathway of postsynaptic sympathetic axons of head + neck

Answer 36

enter internal + external carotid nerves
travel to organs on surface of internal + external carotid arteries

(ophthalmic artery carries sympathetic axons into orbit)

Question 37

which CN do parasympathetics axons leave the CNS via?

Answer 37

ALL PARAsympathetic axons leave CNS via -
III, VII, IX + X

+ sacral spinal nerves

Question 38

which muscles of the eye have secondary movement?

Answer 38

all bar medial + lateral rectus