Reflex and nerve anatomy

Question 1

What does the opthalmic nerve CNVI supply?

Answer 1

upper eyelid
cornea
conjunctiva
skin of root/bridge/tip of nose

Question 2

What does the maxillary nerve CN V2 supply?

Answer 2

lower eyelid
maxilla
ala of nose
mucosa of lip

Question 3

What is the affernt nerve for the blink reflex?

Answer 3

opthalmic nerve CNVI to trigeminal ganglion CNV to the pons

Question 4

What is the efferent nerve for the blink reflex?

Answer 4

CNVII facial nerve

Question 5

What is the pathway of the oculomotor nerve?

Answer 5

connects with the CNS at the junction between the midline and pons

Question 6

What is the role of the ciliary nerves?

Answer 6

control the diameter of the iris and refractive shape of the lens
in far vision - ciliary body relaxes - lens flattens
in near vision - ciliary body contracts - lens spherical

Question 7

What supplys the long cillary nerves?

Answer 7

sympathetic and somatic sensory

Question 8

What supplys the short cillary nerves?

Answer 8

sympathetic and parasympathetic

Question 9

What is the vestibo-ocular reflex?

Answer 9

turns eye in the opposite direction to head movement

Question 10

What is teh oculocardiac reflex?

Answer 10

reflex bradycardia in response to tension on extraocular muscles or pressure in the eyes

Question 11

What are the sympathetic responses from eyes?

Answer 11

eyes wider
dilate pupil
more light into the eyes
focus on far objects
emotional lacrimation

Question 12

What are the parasympathetic responses from the eyes?

Answer 12

eyes narrower
pupil constricts
focus on close up objects
reflex lacrimation

Question 13

How does the levator palpebrae superioris open the eyes wider?

Answer 13

post synaptic sympathetic fibres

Question 14

What is a mydriatic pupil?

Answer 14

non physiologically enlarged pupil e.g. due to drugs

Question 15

What is a miotic pupil?

Answer 15

non physiologically constricted pupil (opiates)

Question 16

What does a fixed pupil indicate?

Answer 16

CN II pathology - optic nerve

Question 17

What are the two types of dilator pupil fibres?

Answer 17

fixed - originate around the external circumferance of the iris
mobile - insert around internal circumference

Question 18

What are the afferent signals for the eye?

Answer 18

optic nerve CNII

Question 19

What are the efferent signals for the eye?

Answer 19

oculomotor nerve CN III

Question 20

What are the 3 components of the accomodation reflex?

Answer 20

bilateral pupillary constriction
bilateral convergance - medial rotation of both eyes
bilateral relaxation of the lens - spherical

ALL DONE BY CNIII

Question 21

What are the 3 types of lacrimation tears?

Answer 21

basal
reflex
emotional

Question 22

What are basal tears?

Answer 22

contain lysozomes - enzymes that hydrolyse the bacteria wall - nourish the cornea

Question 23

What are reflex tears?

Answer 23

released in response to mechanical or chemical stimulation
afferent - CN VI
efferent - CN VII

Question 24

What are emotional tears?

Answer 24

in response to happy, sad, frightened

Question 25

What happens to the zonules when ciliary bodies relax?

Answer 25

zonules contract, lens becomes flat

Question 26

What happens to the zonules when ciliary bodies contract?

Answer 26

zonules relax, lens becomes spherical, increases refractory power for close up reading

Question 27

What happens to the lens at the age of 40?

Answer 27

becomes harder so it struggles to become spherical

Question 28

What happens to the lens at the age of 40?

Answer 28

becomes harder so it struggles to become spherical

Question 29

What is horners syndrome?

Answer 29

impaired sympathetic innervation to the head and neck due to: root of neck trauma, carotid dissection, internal jugular vein engorgement, deep cervical node metastases, pancoast tumour - apex of the lung