Anatomy Flashcards by Kieran Ruthven

What are the bones of the orbit? (7)

Frontal, Zygomatic, Maxilla, Nasal, Sphenoid, Ethmoid, Lacrimal

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Label the structures (bones and any landmarks seen)

A: Maxilla (infraorbital foramen)

B: Ethmoid

C: Frontal (supraorbital notch on right)

D: Sphenoid (optic canal)

E: Sphenoid (superior orbital fissure)

F: Lacrimal

G: Nasal

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In orbital blowout fracture, which bone tends to be ruptured?

Zygoma

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Which muscle is this? What are the parts (A and B)?

Orbicularis oculi (CN VII)

A: Orbital part

B: Palpebral part

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List the parts of the orbital fascia

A: Levator palpebrae superoris tendon

B: Superior tarsus

C: Medial palpebral ligament

D: Inferior tarsus

E: Orbital septum

F: Lateral palpebral ligament

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What kind of substance do the tarsal glands secrete?

Lipid

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Label the surface anatomy of the eye

A: Iris

B: Conjunctival blood vessel

C: Lacrimal lake

D: Inferior lacrimal papilla & punctum

E: Lower eyelid lined by palpebral conjunctiva (central part = bulbous conjunctiva)

F: Conjunctival fornix

G: Sclera

H: Limbus (corneo-scleral junction)

I: Location of the lacrimal gland

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Which innervation produces lacrimal fluid?

CN VII parasympathetic

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Where do the tears drain in the eye? Where do they drain to in the nose?

Drain to lacrimal puncta, eventually reach inferior meatus in the nasal cavity (through the nasolacrimal duct)

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What are the 3 layers of the eye?

Fibrous (outer layer containing sclera and cornea)

Uvea (vascular middle layer containing the iris, ciliary body and choroid)

Retina (inner photosensitive layer containing the photoreceptors)

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The ciliary body is located in which layer of the eye?

Uvea/ vascular layer

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What are the 2 parts of the eye? List any sub-parts?

Anterior and posterior segment.

Anterior segment is in front of lens. Divided into anterior (between cornea and iris) and posterior (between iris and suspensory ligaments) chambers.

The posterior segment is everything behind the lens

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Which humours are present in each part of the eye?

Anterior segment = aqueous

Posterior segment = vitreous

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Where is 2/3rds of the refractive power of the eye held?

Cornea

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Floaters are located within which part of the eye??

Posterior segment (within the vitreous humour)

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What is the iridocorneal angle?

Angle between the iris and cornea

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Describe the circulation of aqueous humour (4)

1) Produced in the ciliary body
2) Circulates within the posterior chamber to nourish the lens
3) Passes through pupil into anterior chamber and nourishes cornea
4) Is reabsorbed into the scleral venous sinus (at the Canal of Schlemm located at the iridicorneal angle)

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The opthalmic artery is a branch of which artery?

Internal carotid

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List the parts of the dural venous sinus

A: Internal carotid artery

B: Cavernous sinus

C: Ophthalmic artery (coming off the internal carotid)

D: Pituitary

E: CN II (optic)

F: CN III (oculomotor)

G: CN IV (trochlear)

H: CN V1 (opthalmic division)

I: CN V2 (maxillary division)

J: CN VI (Abduscens)

K: Sphenoidal Sinus

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The opthalmic artery enters the eye within CN II, true or false?

False - it’s the central artery of the retina (which is a branch of the ophthalmic artery)

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T/F: The retina has 2 veins draining it.

False - only 1 (central vein of the retina).

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Which structures drain the orbit? (venous)

Superior and inferior ophthalmic vein

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Where do the opthalmic veins drain to?

Cavernous sinus (through the superior orbital fissure)

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Where does CN II present in the fundus of the eyeball?

Optic disc (blind spot)

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What is the macula? Are any structures contained within it?

Macula is the area with the greatest density of cones. It has a fovea in its centre which is the area of most acute vision.

What are the 3 layers of the retina (from posterior to anterior)

1) The photoreceptors 2) Ganglion cells (anterior to 1) 3) Axons of the ganglons (anterior to 2)

Why is the blind spot in the optic disc a blind-spot?

There are no photoreceptors here

The macula is always where relative to the optic disc?

Lateral

Light from objects in the right visual field is processed where in the brain?

Left primary visual cortext

Light from objects in the lower visual field is processed where?

Upper part of the primary visual cortex

Label these muscles of the right eye

A: Lateral rectus B: Inferior rectus C: Medial rectus D: Superior rectus E: LPS (CN III) F: Superior Oblique G: Inferior Oblique H: CN II

Where do all the rectus muscles originate from? Where do they insert onto?

Originate from common tendinous ring. All insert onto sclera.

What's the rule for remembering somatic motor innervation of the extraocular muscles?

LR6, SO4, AO3

What are the movements of the eye?

Vertical - abduction/adduction Transverse: Elevation/depression Anterioposterior: Intorsion/ Extorsion

What are the only extraocular muscles which do not have secondary movements?

Medial and lateral rectus

Describe which muscles are tested through the eye movements listed

A: Superior rectus B: Inferior rectus C: Superior oblique D: Inferior oblique E: Medial rectus F: Lateral rectus

The superior rectus and inferior oblique oppose which eye motion?

Rotation

The superior oblique and inferior rectus oppose which eye movements

Adductors / abductors

Do all patients with raised ICP have visual symptoms?

No, though most do - 65-75% report they do

Symptoms of raised ICP

Transient blurry vision, diplopia, loss of vision, pupil changes

Does raised IOP have to be bilateral?

Can be bilateral or unilateral

What are the 3 layers of the meninges from outside to innermost?

- Dura - Arachnoid - Pia

What layer of the meninges contains the venous sinuses?

Dura mater

What layer of meninges does the CSF circulate in?

Subarachnoid space

How many mL of CSF is produced per day (total)

400-500mL

What layer does the spinal cord end at? Where are LPs performed?

End = L2 LPs = L3/L4

T/F: CN III carries motor and sensory fibres

False - only motor

How does the eye move in a CN IV nerve palsy?

Up and to the right

Where will the eye move in a CN VI palsy?

Towards the median side

Which nerve supplies sensory supply to the conjunctiva, cornea and tip of nose?

Ophthalmic nerve of CN V

Which nerve supplies sensory supply to rhe skin over the lower eyelid, maxilla, and wings of nose?

Maxillary nerve of CN V

Which nerve supplies sensory information over the mandible?

Mandibular nerve (CN V3)

Which nerve emerges through the supraorbital foramen of the frontal bone?

Supraorbital nerve (a branch of CN V1)

Which nerve emerges through the infraorbital foramen on the maxilla?

Infraorbital nerve (CN V2)

Which nerves are involved in the blink reflex?

CN V1 (sensing) CN V CN VII (efferent motor)

Sympathetic nerves emerge between which levels

T1-L2

Where does the cervical part of the sympathetic trunk emerge (vertebral level)?

T/F: Sympathetic trunk is carried only on the internal cartoid artery.

False - internal and external

Which artery does sympathetic innervation travel along to the eye?

Ophthalmic artery

What nerves do the parasympathetic fibres emerge from (4)

- CN III - CN VII - CN IX - CN X

T/F: Parasympathetic fibres travel along the body wall.

False - they travel straight to the organs (unlike sympathetic trunks)

The long ciliary nerves contain which type of nerve fibres

Sympathetic, somatic sensory

The short ciliary nerves contain which type of fibres

Sympathetic, parasympathetic

Label the structures

A: Long ciliary nerve B: Short ciliary nerve C: CN V1 D: Ciliary ganglion

Which nerve is responsible for the FIRST part of the blink reflex?

Long ciliary nerve

What reflex is this: "Turns the eyes in the opposite direction to a head movement"

Vestibulo-ocular reflex

What reflex is this: "Reflex bradycardia in response to tension on extraocular muscles or pressure on eye"

Oculocardiac reflex | (Requires functional CN V1 & CN X)

What does sympathetic stimulation do to the pupil?

Opens wide

Sympathetic function is essential for near/far vision?

Far vision

The LPS muscle contains only smooth muscle, T/F?

False - contains skeletal PLUS smooth muscle

A fixed dilated pupil is indicative of which nerve pathology?

CN III (loss of parasympathetic stimulation which normally closes the pupil)

The pupil in Horner's syndrome is enlarged/pinpoint?

Pinpoint (loss of sympathetic stimulation)

Which nerve is involved in the afferent portion of the pupillary light reflex? What about the efferent motor reflex?

CN II afferent CN III efferent

Where is the Edinger-Westphal nucleus?

2nd order neurone

In far vision, the ciliary muscles relax due to what...

Lack of parasympathetic innervation

When the ciliary muscle contracts, the lens becomes which shape? What vision is this useful in?

Spherical. Focuses on near objects

In far vision, what happens to the lens?

Flattens to focus on FAR vision objects

What are the 3 parts of the accomodation reflex?

1) Bilateral pupillary constriction 2) Bilateral convergence of both eyes to the midline 3) Bilateral relaxation of the lens (contracted ciliary muscles due to parasympathetic innervation from CN III)

Reflex tears are produced by parsympathetic fibres from which nerve?

CN VII

Where does CN VII exit the petrous part of the temporal bone? Which foramen does it exit from?

Stylomastoid foramen Internal Acoustic Meatus

Which nerves are involved in carrying CN VII fibres to the lacrimal glands?

V2 (maxillary nerve) then V1 (ophthalmic nerve)

What is the underlying pathology of Horner's Syndrome?

Compression of the cervical parts of the sympathetic trunk (can be due to pancost tumour, carotid dissection, root of neck trauma)

Clinical signs of Horner's Syndrome (4)

1) Miosis (constricted pupil = unopposed parsympathetic activity) 2) Ptosis (no more innervation to a tarsal muscle, not LPS) 3) Reduced sweating 4) Increased warmth and redness

Which muscles open the eye? What CN innervates them?

Levator Palpebrae Superoris & Muller's Muscle CN III

Which muscle closes the eyelid? What CN is it controlled by?

Orbicularis oculi. Controlled by CN VII

What part of the orbicularis oculi closes the eye tightly? What part is normal blinking?

Tight = orbital part Blinking = Palpebral part

What nerve must be intact for a reflex tear production?

Trigeminal

What nerve "feels" the eye needs tears? What nerve produces tears?

CN V CN VII parsympathetic fibres

The eyeball is lined by what kind of conjunctiva?

Bulbar