Important Reflexes of the Orbital Region

Question 1

Opthalmic nerve

Answer 1

CN V1 -
upper eyelid
cornea
conjunctiva
skin of the root/bridge/tip of the nose

Question 2

Maxillary Nerve

Answer 2

CN V2 -
skin of lower eyelid
skin over the maxilla
skin of the alla of the nose
skin/mucosa of the upper lip

Question 3

Mandibular nerve

Answer 3

CN V3 -
Skin over the mandible and temperomandibular joint
angle of mandible supplied by C2,3 spinal nerves

Question 4

Blink (corneal) reflex

Answer 4

Sensory @ CNV1 @ cornea > trigeminal ganglion > CNV > Pons > CNVII > motor function (eyelid part of orbicularis oculi)

Question 5

Route of sympathetic axons

Answer 5

passes down spinal cord
Exits @ T1-L2 spinal nerves
Passes into spinal nerves (anterior and posterior rami)
Passes into splanchnic nerves to supply organs

Question 6

Parasympathetic outlfow

Answer 6

CN III, VII, IX + X

Sacral Spinal Nerves

Question 7

Parasympathetic innervation of eye

Answer 7

Iris + ciliary muscles

Lacrimal Gland

Question 8

Occulomotor nerve supplies somatic motor to:

Answer 8

CNIII
Superior, Medial + Inferior Rectus
Inferior Oblique
Levator Palpebrae Superioris

Question 9

Occulomotor Nerve supplies presynaptic parasympathetic axons to ….

Answer 9

ciliary ganglion

Question 10

Ciliary ganglion

Answer 10

branches into ciliary nerves that supply autonomic axons to control diameter of iris and refractive shape of lens

Question 11

Fight or flight

Answer 11

maximal eyelid elevation/ wide eye opening

Question 12

Light reflex

Answer 12

Pupillary dilation/ constriction adjusting light entry

Question 13

Accomodation reflex

Answer 13

focussing lens for far and near vision

Question 14

Vestibulo-ocular reflex

Answer 14

Turns eye in opposite direction of head movement.

CNVIII [balance] and CNs III, IV + VI

Question 15

Oculocardiac reflex

Answer 15

reflex bradycardia in response to tension on extraocular muscles or pressur eon eye (CNV1 + CNX)

Question 16

Sympathetic function of eye

Answer 16

Open eyes wider
more light into eyes
focus on distant objects
emotional lacrimation

Question 17

Parasympathetic function of eye

Answer 17

allow orbicularis to work
get less light into eye
focus on near objects
reflex lacrimation (wash away stimulant/ clean the cornea)

Question 18

levator palpebrae superioris

Answer 18

located in upper eyelid
contains both skeletal and smooth muscle.
So open wide in fight or flight

Question 19

Drugs that induce dilation of pupil

Answer 19

mydriatic

Question 20

sympathetics do what to the pupil?

Answer 20

dilate (e.g. dim light, fight or flight)

Question 21

Parasympathetics do what to the pupil?

Answer 21

constrict the pupil (e.g. bright light, ‘rest & digest’)

Question 22

radially arranged fibres for pupillary dilatation

Answer 22

dilator pupillae

Question 23

fibres that encircle pupil for constriction

Answer 23

sphincter pupillae

Question 24

In far vision what does the ciliary muscle do?

Answer 24

it relaxes - ligaments tighten so lens flattens

Question 25

In near vision what does the ciliary muscle do?

Answer 25

it contracts - lens becomes squeezed into spherical shape

Question 26

Symptoms of Horners Syndrome

Answer 26

Miosis (constriction of pupil) Ptosis (drooping of upper eyelid) Reduced Sweating Increased warmth and redness

Question 27

Cause of Horner's Syndrome

Answer 27

Compression of cervical parts of the sympathetic trunk