Week 8 - Eyelids and extraocular muscles

Which CN innervates the LR muscle?

CN VI - Abducens

Which CN innervates the SO muscle?

CNIV - trochlear

Where does the Inferior oblique muscle arise from?

Floor of orbit - orbital plate of maxilla

What is an entropion eyelid movement?

INward turning of eyelid margins

What are the functions of the tarsal plate?

Maintains shape and rigidity of eyelid, embedded with Meibomian glands, anchor for palpebral ligaments and LPS tendon

Name: Slow eye movements for gaze tracking to maintain foveation on object of interest

Pursuits

Name: Lies between orbicularis muscle and tarsal plate. Visible 'grey line' between anterior and posterior lid structures.

Submuscular areolar layer

For EOMs, venous return is done by which veins?

Superior and inferior ophthalmic veins

In the centre of the eyelid the orbital septum thickens and forms the what?

Tarsal plate

Which nerve innervates the eyebrows?

4 muscles of CNVII - Frontalis, orbicularis oculi, corrugator and procerus

What nerves innervate the sensory component of the eyelids?

5 branches of CN V: lacrimal, supraorbital, infratrochlear, supratrochlear and infraorbital

Hint to remember secondary and tertiary actions of EOMs

oB-liques = aBduct S-uperiors IN-tort (sin to forget it)

What are the functions of the upper and lower Muller muscles? Where is each derived from?

Upper - assist LPS in lid elevation, derived from LPS. Lower - lowers lower eyelid, derived from inferior rectus muscle

Name: Above optic foramen, also called the Tendon of Lockwood, attached to body of sphenoid, bridges over SOF

Upper portion of AOZ

Name at least 3 functions of the eyelids

- Protection (light/trauma) - Sensory function (lashes) - Maintains globe position in orbit - Tear distribution/drainage - Tear production (oil, lacrimal secretion, mucin) - Blink (tear renewal)

All EOMs are supplied by the muscular branches of the ophthalmic artery, which EOMs do the following branches supply? - Lateral branch - Medial Branch - Lacrimal Artery - Infraorbital Artery The arteries to rectus muscles in turn give rise to what arteries?

- Lateral branch: LR, SR and SO - Medial Branch: IR, MR and IO - Lacrimal Artery: LR - Infraorbital Artery: IO Anterior ciliary arteries

Name: eye movements involving one eye - name the following movements: Outward from nose Inward toward nose Elevation Depression Rotation around Z-axis

Abduction - Outward from nose Adduction - Inward toward nose Supraduction - Elevation Infraduction - Depression Cyclo-duction (torsion) - Rotation around Z-axis

Diagram of EOMs arising from Annulus of Zinn

Arise from tendinous ring at apex of orbit (Annulus of Zinn), AOZ overlies optic foramen and medial part of SOF

What does the Muscle of Muller do? How is it innervated? What effect does Horner's Syndrom have in regards to this muscle?

Assists in lid position and upper lid elevation, sympathetic response - elevates eyelid in fight/flight response. Horner's syndrom causes partial ptosis

Fill in: Vergence (binocular and disjunctive movements) - "?" - bilateral nasal movement "?" - bilateral temporal movement "?" - nasal clockwise rotation "?" - temporal counterclockwise rotation

Convergence - bilateral nasal movement Divergence - bilateral temporal movement Incyclovergence - nasal clockwise rotation Excyclovergence - temporal counterclockwise rotation

Fill in: Version (binocular and conjunctive movements) - "?" - to the right "?" - to the left "?" - up "?" - down

Dextroversion - to the right Laevoversion - to the left Supraversion - up Infraversion - down

In regards to it's effect on the LPS, CNIII lesions/palsy can cause what symptom?

Full ptosis

Which rectus muscles originate from upper portion of AOZ?

Gives rise to SR and parts of MR and LR

Fill in: Skin of eyelids - Glands of "?" (sebaceous) open into lash follicles. Glands of "?" (sweat) open onto lid surface. "?" gland orifices border skin and conjunctiva.

Glands of Zeis Glands of Moll Meibomian gland

What is a blepharospasm?

Involuntary/prolonged contraction of eyelid muscles

Equation for EOM innervation?

LR6(SO4)3

Venous drainage of the eyelids: the medial and temporal aspect each drain into what veins?

Medial - ophthalmic and angular veins Temporal - superficial temporal vein

Palpebral Lymphatic drainage diagram

Medial aspect - submandibular nodes Lateral aspect - Superficial parotid nodes

Name: smooth muscle, receives sympathetic innervation, attached to tarsal plate

Muller's muscle

EOMs muscle insertion diagram

Muscles do not insert symmetrically - spiral of Tillaux

What is an ectropion eyelid movement?

OUTward turning of eyelid margins

What are the 3 muscles located in the eyelid? Which nerves innervate these?

Orbicularis oculi (temporal and zygomatic branches of CNVII), Muscle of Muller (sympathetic NS - superior cervical sympathetic ganglion), LPS (superior division of CNIII)

What are the 3 striated muscles of the eyelids?

Orbicularis oculi, Muscle of Riolan and Levator Palpebrae Superioris

Name: membranous sheet that separates the eyelid from the content of the orbital cavity such as orbital fat

Orbital septum

Palpebral vasculature diagram

Originate from ophthalmic artery, each artery divides into 2 branches and 2 arches in each lid

What are the 3 sections of the orbicularis oculi?

Palpebral part (gentle closure), Orbital part (forceful closure) and Muscle of Riolan (lid margin)

What is the centre of rotation of the eye?

Point around which eye rotates

What is the primary, secondary and tertiary actions of the lateral rectus?

Primary and only action is Abduction

What is the primary, secondary and tertiary actions of the Medial rectus?

Primary and only action is Adduction

What is the primary, secondary and tertiary actions of the inferior rectus?

Primary: Depression Secondary: Extorsion Tertiary: Adduction

What is the primary, secondary and tertiary actions of the superior rectus?

Primary: Elevation Secondary: Intorsion Tertiary: Adduction

What is the primary, secondary and tertiary actions of the inferior oblique?

Primary: Extorsion Secondary: Elevation Tertiary: Abduction

What is the primary, secondary and tertiary actions of the superior oblique?

Primary: Intorsion Secondary: Depression Tertiary: Abduction

What are the 3 types of blinking?

Reflex (threat/noise), voluntary, involuntary (sneezing)

What is the Vestibulo-ocular Reflex (VOR)?

Reflex eye movement, designed to stabilise retinal images during head movements. Eyes move in direction opposite to head movement.

What is the Optokinetic Nystagmus (OKN)?

Reflex eye movement, driven by visual detection, direction and velocity of retinal image. Eyes follow to limit of movement, then flick back

Which EOMs are innervated by CNIII?

SR, IR, MR, IO and LPS in eyelid

Name: Fast bilateral eye movements from one fixation point to another

Saccades

Fill in: The superior oblique muscle arises from the body of the "?". The SO tendon runs through a fibrocartilage loop (called the "?"), attached to the "?" at the superomedial margin of the orbit.

Sphenoid bone, trochlea, trochlear fossa

EOMs Clinical Q answer - Brown's Syndrome

Uneven elevation and adduction

Which of the following glands is not present within the eyelid: Select one: a. Gland of Manz b. Gland of Zeis c. Gland of Moll d. All of these e. Meibomian gland

a

Which of the following statements is incorrect: Select one: a. The speed of the eye movement is constant throughout optokinetic nystagmus b. The 'double H' clinical test is used in the assessment of ocular motility c. Left lateral rectus and right medial rectus are the yoke muscles in left gaze d. Brown's syndrome affects the tendon of the superior oblique muscle as it moves in the trochlea e. Torticollis may be acquired by patients with muscle palsies to compensate for the perceived subjective diplopia

a

Bell's Palsy... Select one: a. Never occurs in children below puberty age b. Sufferers may require topical lubrication and lid taping to protect the ocular surface from desiccation c. Can only be diagnosed with a positive antibody blood test d. Only occurs in immuno-compromised patients e. Is associated with interruption to cranial nerve III (oculomotor)

b

The Annulus of Zinn... Select one: a. Gives rise to six extraocular muscles b. Is a tendinous ring at the apex of the orbit c. Is located inferior to the optic foramen d. Contains the suspensory ligament of Lockwood and tendon of Zinn e. Refers to a network of blood vessels supplying the optic nerve

b

Trichiasis refers to... Select one: a. Loss of eyelashes from the eyelid margin b. Bacterial infection of the Meibomian glands c. Droop of the upper eyelid d. Abnormal misdirection of eyelashes towards the globe e. Laxness of muscle tone at the margin of the orbit

d

Which of the following is not a function of the eyelids: Select one: a. Tear film distribution b. Protection of the globe c. Maintenance of ocular surface intergrity d. Assistance with ocular movement e. Maintenance of globe's position within the orbital cavity

d

Which of the following statements is correct: Select one: a. Trauma or loss of innervation to the Muller's muscle of the eyelid will cause a complete ptosis (droop) of the lid b. None of these c. Orbicularis oculi and levator palpebrae superioris muscle are innervated by the same neural pathway d. Mechanical trauma to the eyelid may cause oedema in the submuscular areolar layer e. Orbital septum separates the eyelid from the globe

d

Which of the following statements is incorrect: Select one: a. One action of the superior oblique muscle is abduction b. Inferior rectus depresses, adducts and extorts the eye c. Lesion of Cranial Nerve I would have no effect on eye movements d. All rectus muscles attach to 23 degree relative to the visual axis e. Lateral rectus only has one action (abduction)

d

Which of the following statements about cranial nerves is correct: Select one: a. Cranial nerve VII (facial) innervates the lateral rectus muscle b. Cranial nerve I is responsible for vision c. There are 10 pairs of cranial nerves d. Cranial nerve V (trigeminal) is involved in eye movement e. Cranial nerve III (oculomotor) innervates the superior rectus muscle

e

Which of the following statements about eye movements is correct: Select one: a. The four rectus muscles insert equidistant to the limbus b. None of these c. Saccade and pursuit movements occur at the same speed d. Terms: duction, version and vergence refer to movements of both eyes e. Both oblique muscles insert posterior to the equator

e

External image of eye

space between two eyelids is called palpebral fissure