Week 1 - D - Anatomy - Orbital Autonomics

Question 1

If sustaining a fracture to the inferiorlateral margin of the orbit, what bone is this? What can happen due to this?

Answer 1

Zygomatic bone Can cause trapping of the inferior rectus muscle - eye is unable to move superiorly and cause vertical diplopia

Question 2

What nerve goes through the inferior orbital fissure and then travels along the infraorbital canal of the maxillary bone? What is the nerve known as before it exits the orbit via the infraorbital foramen?

Answer 2

Maxillary nerve enters orbit via the inferior orbital fissure Exits the orbit via the infraorbital foramen where it is known as the infraorbital nerve

Question 3

In a zygomatic bone fracture, this can impede on the NVB in the infraborital canal, damaging the nerve What can the damaging of this nerve result in?

Answer 3

Can result in general sensory deficit of the facial skin in the maxillary region

Question 4

CNV1 – ophthalmic division of trigeminal nerve – supplies the whole forehead What else does it supply with general sensory innervation?

Answer 4

The upper eyelid, the cornea, the conjuctivae (bulbar and palpebrae) and the bridge/tip of the nose

Question 5

What nerve from the ophthalmic division of the supplies the lacrimal gland with sensory information?

Answer 5

The lacrimal nerve - when something touches the cornea/conjunctivae

Question 6

CN V3 (mandibular nerve) supplies: - the skin over the mandible and temporomandibular joint Which part of the mandible does the sCN V3 not supply and what supplies it?

Answer 6

C 2 and 3 spinal nerves supply the angle of the mandible

Question 7

How does the nose have a dual nerve innervation for sensory innervation?

Answer 7

CN V1 innervates the bridge and tip of the nose CN V2 inneravates the ala of the nose (the nostrils)

Question 8

What is the corneal reflex better known as and what nerves are involved?

Answer 8

Better knwon as the blink reflex The opthalmic division of the trigeminal nerve (sensory to cornea) and the facial nerve (CN VII)

Question 9

The afferent (sensory) limb of the corneal reflex is what nerve? Where does this nerve converge with its other branches?

Answer 9

The afferent limb is the opthalmic nerve (CN V1) Converges at the trigeminal ganglion

Question 10

When the trigeminal nerve is about to give off its divisions at the trigeminal ganglion, which foramen do each of the divisions go through?

Answer 10

CN V1 - superior orbital fissure CN V2 - foramen rotundum CN V3 - foramen ovale

Question 11

The large sensory root of the trigeminal nerve arises at which structure of the brain?

Answer 11

Arises in the pons

Question 12

In the brain there are connections between the trigeminal and facial nerve so the facial nerve is the motor nerve to facial expression The facial nerve is the efferent (motor) limb of the corneal reflex What muslce does the facial nerve innervate to cause blinking?

Answer 12

Innervates the orbicularis oculi (specifically the palpebral part for blinking)

Question 13

Where does the sympethetic chain extend from?

Answer 13

Extends from spinal nerves T1 to L2

Question 14

For sympethetic axons from the CNS, where do the ganglion exist? What is the presynaptic neurotransmitter?

Answer 14

The ganglion exist in the sympathetic chain and the presynaptic neurotransmitter is acetylcholine (ACh)

Question 15

the presynaptic axon releases acetylcholine at the synapse to stimulate the cell body of the postsynaptic axon What is the postsynaptic sympathetic neurotrasmitter?

Answer 15

This is noradrenaline - this stimulates an organ response

Question 16

regarding innervation of the eye, what level of the spinal nerves do the sympathetic presynaptic axons arise? What are the three ganglia that then synapse?

Answer 16

Arise at T1 and synapse at the superior, middle and inferiror cervical sympathetic ganglia

Question 17

Is sympathetic innervation thoracolumbar or craniosacral?

Answer 17

It is thoracolumbar

Question 18

Where do the postsynaptic sympathetic axons form a plexus around from T1?

Answer 18

Form a plexus around the internal and external carotid arteries (ICA and ECA)

Question 19

The postynaptic ganglions then hitch a ride along side the arteries on the way to supply the orbit in this case What branch of the internal carotid artery does the sympathetic axons travel along?

Answer 19

Travel along the ophthalmic artery which supplies the orbit

Question 20

What can the inferior cervical ganglion and the 1st thoracic ganglion fuse to form?

Answer 20

Can fuse to form the stellate ganglion

Question 21

Presynaptic sympathetic axons have a short presynaptic (ACh) and longer postsynaptic (noradrenaline) The ganglion is located on the sympathetic chain How does sympathetic differ from parasympathetic?

Answer 21

Parasympathetic has a long presynaptic with the ganglion being located in the organs There is therefore a very short postsynaptic axon Both the pre and post synaptic axons are acetylcholine in parasympathetic

Question 22

all presynaptic parasympathetic axons leave the CNS in cranial nerves or sacrospinal nerves What are the parasympathetic cranial nerves?

Answer 22

Oculomotor (CN III) Facial (CN VII Glossopharyngeal (IX) Vagus (X)

Question 23

What type of tissue does parasympathetic and sympathetic axons work on?

Answer 23

Works on smooth muscle and glandular secretions

Question 24

Ganglia of head are associated with branches of CN V. T/F?

Answer 24

true even though parasympathetic ganglia of head are formed from CN III, CN VII, or CN IX, they are associated with branches of CN V thus parasympathetic postganglionic fibers reach their targets via trigeminal nerve (CN V)

Question 25

What is the branch of the mandibular division of the trigeminl nerve that the glossopharyngeal nerve suses to reach its target that is the parotid gland?

Answer 25

The auriculotemporal branch

Question 26

State the ganglion of the CN III, VII and IX?

Answer 26

CN III - oculomotor nerve - ciliary ganglion CN VII - facial nerve - pterygopalatine ganglion and submandibular ganglion CN IX - otic ganglion

Question 27

Why is it the sympathetic and parasympathetic (both part of autonomic nervous system) control smooth muscle and glandular secretions and not skeletal muscle?

Answer 27

Supplies smooth muscle and glandular secretions as you don’t have active control over smooth tissue You do have active control over your smooth muscle so this is under control from the CNS

Question 28

Where does the oculomotor nerve connect with the CNS? What extraocular muscles does it supply?

Answer 28

Connects with CNS near the midline at the junction between the midbrain and the pons Motor innervation to superior rectus. inferior rectus, medial rectus and inferior oblique

Question 29

Once leaving the brain the CN III has to leave the cranial cavity via the superior orbital fissure Also cranial nerve IV, VI and V1 leave via the superior orbital fissure They then spread and supply different things including the muscles surrounding the eye attaching to the eyelid and sclera of eyeball

Answer 29

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Question 30

There are six autonomic reflexes of the eye Maximal eyelid elevation during fight or flight is one of them Try name the other five?

Answer 30

The (pupillary) light reflex The accomodation reflex The reflex tear prodcution (lacrimation) The vestibulo-ocular reflex The oculocardiac reflex

Question 31

Before tackling the main reflexes that alter the amount of vision entering the eye and tears How does the vestibulo-ocular reflex work?

Answer 31

The eyes moe in the opposite direction of head movement in order to keep the eyes focused in the center

Question 32

What are the cranial nerves that are involved in the vestibulo-ocular reflex? Think, balance and muscles to move the eye

Answer 32

CN VIII - vestibular nerve of CN VIII CN III - extraocular eye muscles CN IV - lateral rectus extraocular muscle CN VI - superior oblique extraocular muscle

Question 33

CNS connections between CN V1 & CN X control the oculocardiac reflex How does this work?

Answer 33

There is reflex bradycardia in response to tension (traction) on the extra-ocular eye muscles or pressure on the eye CNV1 is afferent pathway CN X is efferent pathway

Question 34

What is given to treat the bradycardia caused by the oculocardiac reflex during eg traction in surgery?

Answer 34

Give atropine - antimuscarinic that inhibits the parasympathetic nervous system therefore causing vasoconstriction

Question 35

How does the sympathetic system allow for the opening of the eyes wider?

Answer 35

Causes the dilator pupillae of the iris to pull the pupil open allowing more light in

Question 36

Sympathetic functions cause emotional lacrimation When else does the sympathetics cause the eyes to widen?

Answer 36

When it is dark or when a person is in fight or flight

Question 37

The levator palpebrae superioris contains both skeletal and smooth muscle How is it in horner’s that the drooping of the eyelid occurs? (ptosis)

Answer 37

In horner’s when the sympathetic ganglion is damaged The sympathetic innervation to the smooth muscle in the levator palpabrae superioris is damaged and therefore lid retraction is not as good causing drooping

Question 38

What arises from the superior cervical ganglion that ends up with the branching out to supply orbital structures with sympathetic innervation?

Answer 38

The internal carotid nerve arises forming the internal carotid plexus on the internal carotid artery This then travels along the ophthalmic artery to give branches

Question 39

What other muscle that causes lid retraction of the eyelid can be affected due to damage to the sympathetic ganglion?

Answer 39

The superior tarsal muscle (Muller’s muscle) also causes lid retraction and is innervated by postganglionic sympathetic fibres

Question 40

In dim light or fight/flight, what causes dilation of the pupil?

Answer 40

The sympathetics cause dilation of the pupil

Question 41

The dilator pupillae have a mobile insertion of the radially arranged fibres around the inernal circumference of the iris (the internal circumference is formed by the sphincter pupillae muscles) Where is the insertion of fixed pupillae fibres?

Answer 41

Inserts on the external circumference of the iris In between the green and yellow lines is the iris

Question 42

A mitoic pupil is a non-physiologically constricted pupil (heroin can cause this) What is the opposite of this and name a substance that can cause this?

Answer 42

a non-physiologically enlarged pupil is a mydriatic pupil Cocaine and marijuana can cause this

Question 43

A fixed pin point pupil showing no response to light is often a serious pathological problem What type of substance can be expected?

Answer 43

Opiate drugs (search for needle wounds)

Question 44

parasympathetics constrict the pupil (in bright light and “rest & digest”) a non-physiologically constricted pupil is a miotic pupil (not meiotic) What syndrome can this arise in and why?

Answer 44

Can arise in Horner’s syndrome as there is no sympathetic supply to dilate the pupil

Question 45

What nerve should you be at worry for in fixed dilated pupil, which shows no response to light?

Answer 45

Worry for CN III, as there will therefore be no parasympathetic supply to dilator pupillae

Question 46

The pupillary reflex when exposed to light casuses constriction of both pupils The eye the light is shone into is the direct light reflex What is the eye on the contralateral side that constricts knwon as?

Answer 46

Known as the consensual light reflex

Question 47

the (special) sensory (afferent) limb of the pupillary reflex is the ipsilateral CN II (the optic nerve) What is the motor limb of the pupillary reflex in response to light?

Answer 47

This is the oculomotor nerve (CN III) - the motor reflex is bilateral hence the consticted pupils inboth the direct and consensual eye

Question 48

The pupillary light reflex is a 4 neurone chain It begins with the sensory of the bright light This is located on the retinal ganglion cells and then travel where?

Answer 48

Travel on the ipsilateral optic nerve to intersect at the optic chiasm on rout to the midbrain

Question 49

Where in the midbrain do the optic nerve axons synapse?

Answer 49

In the pretectal nucleus

Question 50

2nd neurones (bilateral) = located entirely within the midbrain & connect the pretectal nucleus to the next synapse in the Edinger Westphal nucleus What is located in the edinger westphal nucleus?

Answer 50

The cell bodies f the parasympathetic axons of CN III

Question 51

Where do the cell bodies from the edinger westphal nucleus travel to, to synapse?

Answer 51

They travel to the ciliary ganglion where they then become postsynaptic neurotransmissions

Question 52

Once synapsed in the ciliary ganglion, the axons travel in the short ciliary nerves to where to have their effect?

Answer 52

Travel to the sphincter pupillae muscles

Question 53

Describe the pupillary reflex stages

Answer 53

1. The retinal ganglion cells detect lie in the nasal retina (temporal visual field) and travel back to synapse in the prectectal nucleus in the midbrain 2. The axons then travel from pretectal nucleus to edinger westphal nucleus in the midbrain to synapse where the cell bodies of parasympathetic fibres of CN III are located 3. Neurones pass from EW via CNII to the ciliary ganglion where they synapsein the ciliary ganglion 4. The short ciliary nerve travels to the sphincter pupillae to cause contraction

Question 54

To control the refractive shape of the lens the ciliary muscles contract or relax Bigger lens = bigger refraction = seeing closer object Flatter lens = smaller refraction = seeing far object What happens when the ciliary muscle relax?

Answer 54

When they relax, the supsensory ligament attaching to the lens tightens causing the lens to flatten and therefore you cans see further opposite for when the ciliary muscles contract

Question 55

Do sympathetics play a role in seeing further or closer?

Answer 55

As the ciliary muscles are under parasympathetic control from the CN III they contract when parasympathetic axons are present and relax when not so the sympathetic axons do not play a role

Question 56

There are three components of the accomodation reflex for light Need to make sure can the light doesnt diverge when hitting the reina causing a blurred image, that the eyes can see the close object in midline and the lens is the correct size for a close up image What three things happen?

Answer 56

Bilateral pupil constriction - stops the blurry image from diverging light Bilateral medial rotation of the eyes - Bilateral contraction of the ciliary muscles to cause relaxed enlarged lens

Question 57

Tears occur due to basal tears, reflex tears and emotional tears Basal tears are important in corneal health What are the nerve impulses for reflex tears?

Answer 57

If something touches the corneea The afferent limb is the CN V1 which innervates the cornea and conjunctivae, once stimulated axons travel along to the trigeminal nerve and then CN V and CN VII CNS connections cause an efferent response from CN VII Parasympathetic axons originate from CN VII and travel to cause lacrimation

Question 58

What branch of the facial nerve supplies the parasympathetic supply to the lacrimal gland causing lacrimation?

Answer 58

The greater petrosal nerve - eventally hijacks a ride on the lacrimal nerve branch of the opthalmic division to reach the lacrimal gland