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Anat Block 2 > Lec 9 > Flashcards

Lec 9 Flashcards

1
Q

Describe the orbit

A

Eyeball only partially fills the orbit, remaining space occupied by nerves vessels and orbital fat. Orbital fat is metabolically spared and is last to go in starvation. Orbit is surrounded by air spaces, ethmoidal and maxillary.

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2
Q

Impacts on orbit

A

Sphere hits orbit directly = blow out fracture, orbit can be forced into maxillary sinus. Less forceful blow = Hephema = blood accumulates in anterior chamber of eye

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3
Q

General orientation of orbit

A

Pyramidal cavity with 7 bones, lateral wall is 45 degs from mid plane

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4
Q

What is the architecture of the roof

A

Frontal bone and lesser wing of sphenoid
Supra orbital notch for supraorbital artery and supraorbital nerve V1
Laterally is fossa for lacrimal gland

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5
Q

What is the architecture for medial wall

A

Ethmoid and lacrimal bone, thin and easily pierced, two foramina communicate the ant and post ethmoidal nerves = branches of nasociliary nerves

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6
Q

What is the architecture for anterior wall

A

Zygomatic and maxillary bones

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7
Q

What is the architecture for lateral wall

A

Frontal process of zygomatic and greater wing of sphenoid

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8
Q

What is the architecture for the floor

A

maxillary bone and palatine, infra orbital groove is V2 as infraorbital nerve

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9
Q

What is the architecture for apex

A

3 openings
1. Optic canal - Optic Nerve and opthalmic artery
2. Superior orbital fissue - orbit to mid cranium opening for entry of CN 3,4,6, V1
3. Inf orbital fissue - communicates with pterygopalatine fossa posteriorly and is opening for V2 at infraorbital notch.
Largelly covered by orbitalis muscle of Muller where contraction = SNS and eyes forward

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10
Q

Describe the eye

A

Observable eye is Sclera, cornea, pigment iris, pupillary aperature. Lacrimal lake in medial corner, adjacent papilla contains inferior puncta to conduct tears to nasolacrimal duct empties into inf meatus in nasal cavity

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11
Q

Describe the eyelid

A

Protect anterior aspect of the eye, palpebral fissure is bounded by up and low palpebral margins meeting medially and laterally at canthi. Upper is more mobil

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12
Q

Describe the subcutaneous tissue of the eyelids

A

very loose and can swell with fluid (puffy) or extravasated (black eye)

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13
Q

What are the structures of the eyelid

A

Contains tarsal plat of dense CT, glands, and conjunctial lining

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14
Q

What are the glands of the eye

A
  1. Meibanian gland - secrete oily component of tears, opening can be clogged leading to chalazion (tarsal cyst)
  2. small sebaceous glands of zeiss at base of hair follicles. Bacterial infections to external sty to hordeolum
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15
Q

Describe the Conjunctiva

A

Palpebral conjunctiva - CT lines inner surface of eye and is reflected onto eyeball as bulbar conjunctiva.
Fornices form where sup and inf conjunctiva meet
Palpebral conj pale = anemia
Conjunctiva is supplied by many arteries, if irritated = bloodshot = hyperemia, infected = conjunctivitis = pink eye, yellow = jaundice

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16
Q

Describe the Tarsal Plates

A

lac glands occupy lateral border, sup and inf tarsal plates merge to form med and lateral palpebral ligaments inserting into margins. Plates attached around orbital margins by orbital septum a facial sheet enclosing anterior portion of orbit.

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17
Q

What are the muscles of up eyelid

A

Levator palpebra m arises at apex of orbit and inserts on up eye tarsal. contraction moves eyelid up. Nerve is CN3 and paralysis leads to ptosis which is dropping eye

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18
Q

What is the bulbar fascia

A

Thin membranous facial sheath around eyeball from sclerocorneal junction anteriorly and optic nerve posteriorly. Capsule forms socket = ball suspension. Triangular expansions from the sheaths of medial and leteral rectus muscles called med and lat check ligaments attached to lacrimal and zygomatic bones serve to limit add and abduction.
Blending of check ligaments and fascia of inf rectus = hammock sling = suspensory ligament of eyeball

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19
Q

General description of extraocular muscles

A

7 voluntary, 6 on globe. 4 rectus course forward pass through opening of bulbar fascia and insert on sclera. Sup, inf, lat, and medial rectus muscles which all originate from tendinous anulus at apex of orbit

20
Q

Describe the Sup oblique

A

Originates from sphenoid, tendon passes through a fibrous pulley (trochlea) and courses backward to insert on pasterolateral quadrent of superior surface of globe

21
Q

Describe in inferior oblique

A

Origin at ant inferior aspect of medial orbital margin, passes backward to insert onto pasterolateral quadrant of inferior surface of eyeball. Draws post part of ball down therefore elevating eyes

22
Q

What is orbital angle

A

orbit angled outward and eyeball orientated anteriorly

23
Q

Muscle functions of extraocular muscles

A

SR - elevates and adducts
IR - depresses and adducts
SO - depresses and abducts
IO - elevates and abducts

24
Q

Rotation of eyeball

A

Sup and inf obliques cause rotation of ball around anteroposterior axis
Medial rotation by SR and SO = intorsion
Lat rotation by IR and IO = extorsion
Absence of mvmt due to lesion = double vision. Eyeball moves by small mvmts = Saccundes

25
Q

Innervation of extraocular muscles

A

Axon to muscle ratio is high - greatly controlled
Oculomotor nerve - LMNs in oculomotor nucleus and has 2 divisions (1) sup for levator palpebra superior and SR (2) inf for MR, IR, IO
Trochlear nerve- LMNs in trochlear nucleus and only CN to exit dorsal surface of brainstem sup to pons. Axons to contralateral SO
Abducens - LR

26
Q

Cavernous sinus interaction with SOF

A

CN 346V1 subject to disruption by carotid aneurysm, pit tumors. inflammatory thrombosis of cevernous sinus interefers with venous drainage resulting in engorgment of retinal vessels causing potential blindness

27
Q

Nerve and vessel entrance into orbit

A

SOF - CNs and opthalmic vein
Optic canal - Optic nerve and opthalmic artery which are joined by CN 3,4,V3 nasociliary while passing through annulus. V1 and 4, frontal and lacrimal branches of V1 pass superior to annulus

28
Q

What are the lesions and conditions associated with the eye

A

Oculomoter nerve paralysis, Abducent nerve paralysis, Trochlear paralysis, Straismus, Diploplia, Nystagmus

29
Q

What are the conditions of Oculomoter nerve paralysis

A

Eye is down and out (LR and SO active), drooping up eyelid (ptosis), pupil dilated (sphincter muscles), loss of accommodation for near vision

30
Q

What are the signs of right abducent nerve paralysis

A

right eye doesnt abduct, medial rectus unopposed, lesion = medial strabismus (cross eyed)

31
Q

What are the conditions of trochlear paralysis

A

eye deviates inward but not down, diplopia upon trying to look down

32
Q

What is Strapismus

A

cross eyed look, needs to be corrected so eyes develop together appropriately

33
Q

What is diplopia

A

2 images, medial or LR involved

34
Q

What is Nystagmus

A

jerky eye mvmts in horizontal plane

35
Q

Describe the arteries to the orbit

A

Opthalmic (int carotid branch) enters at optic canal beneath optic nerve, gives off small central artery to retina (blocked = blind). Other branches are ant and post ciliary arteries to eyeball and accompany branches of V

36
Q

Veins of the orbit

A

Opthalmic veins connect to angular facial, cavernous sinus, and pterygoid plexus.

37
Q

What are some problems that occur with orbital veins

A

Rupture of int carotid in cavernous sinus leads to exopthalmas = dilation and extrusion of ball and heart beat detected by steth
Retinal vein occlusion leads to vision loss due to thrombosis in central retinal vein

38
Q

Targets of SNS around eye and pathologies

A

blood vessels, sweat glands, dilator muscle, sup tarsal muscle of Muller (dmg = wide eye and paralysis = pseudoptosis)
Orbitalis muscle- covers inf orbital fissure, slings under eye (lesion = enopthalmosis, excessive strain = exopthalmosis)
Lacrimal gland

39
Q

What are the presentations of Horner’s syndrome

A

Pseudoptosis (sup tarsal m), miosis (dilator) Enopthalmosis (orbitalis m) Flushed face (sweat glands)

40
Q

What are the targets of PSNS in eye

A

lacrimal gland,located in lateral region associated with levator palpebra superioris which pushes tears

41
Q

Path of the Auto NS

A

preg in sup saliv nuc - 7 as greater petrosal - joined by deep petrosal, containing postG sym nerves, to form vidian canal - preg PSNS syn at pterygopalatine ganglion - V2 zygomatic to V1 lacrimal - tears released by acetylcholine

42
Q

Lesion analysis

A

lesion of facial canal and IAM now reduce tear and saliva along with bells HA Balance and hearing

43
Q

Nerve paths for CN3 PSNS and fx

A

EW - CN3 - nasociliary - postG at ciliary G - ciliary nerve - eye:
Ciliary muscle for accomodation
Iris dilator sphincter muscles

44
Q

Eye sensory info

A

V1 = orbit
nose = ant ethmoid nerve from nasociliary in orbit
Nasociliary has small connections with cil ganglion:
1. sense of ball along axons in ciliary nerve
2. exit the gang - nasocil - V1 - trigem gang - brainstem

45
Q

Explain the consensual blink reflec

A

Normal has any eye touched leads to both eyes blinking. Trigeminal is sense, Facial is blink.
RET blink LET no blink = left trigem
RE blinks by no left = left facial

46
Q

Graves disease affect on eyes

A

exopthalamosis

Anat Block 2 (11 decks)

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