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COM: Neuro (Exam I) > Lecture 13: Anatomy Of The Cavernous Sinus, Orbit & Eye > Flashcards

Lecture 13: Anatomy Of The Cavernous Sinus, Orbit & Eye Flashcards

1
Q

Name the layers of the eyelid

A 
Skin 
Subcutaneous tissue
Muscular layer
Palpebral fascia
Conjunctiva
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2
Q

What muscles make up the muscular layer of the eyelid?

A 
Orbicularis oculi (palpebral and lacrimal portions)
Levator palpebrae superioris
Tarsal muscle (of Muller)
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3
Q

Destruction of the ______________ nerve or one of its branches to the levator palpebrae superioris muscle results in paralysis of this muscle and complete ptosis

A

Occulomotor nerve (CN III)

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4
Q

What is the tarsal muscle of the eyelid innervated by?

A

Postganglionic sympathetic fibers

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5
Q

Horner’s syndrome usually involves paralysis of the __________ muscle causing slight ptosis of the eye

A

Tarsal muscle

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6
Q

The opening for the conjunctiva is called the ________________

A

Palpebral fissure

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7
Q

What does the lacrimal duct drain into?

A

Inferior meatus (in the nose)

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8
Q

The ________________ portion of the optic nerve is vulnerable to ischemia secondary to orbital fracture

A

Intracanalicular portion

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9
Q

The _________ portion of the orbicularis oculi function in gentle closing of the eyelid. the ________ portion of the orbicularis oculi increases the amount of eyelid contact to the surface of the eyeball and dilates the lacrimal sac

A

Palpebral portion; lacrimal portion

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10
Q

The _________ fascia of the eye functions as a complete barrier between the superficial zone and deep zone of the eyelid

A

Palpebral fascia

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11
Q

Describe the palpebra conjunctiva versus the bulbar conjunctiva

A

Palpebral conjunctiva = thin opaque and highly vascular membrane that lines the back of the eyelids

Bulbar conjunctiva = thin, transparent membrane loosely attached to the eyeball

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12
Q

Innervation of the lacrimal gland: The _______________ nucleus sends preganglionic parasympathetic fibers via the _________ nerve, ______________ nerve, and ________ nerve to the ________ ganglion where they synapse. Postganglionic parasympathetic fibers couse to the lacrimal gland via the ____________, __________, and _________nerves. Sympathetic fibers follow a similar course

A

Superior salivatory nucleus; facial (VII) nerve, greater superficial petrosal nerve and Vidian nerve; sphenopalatine ganglion; maxillary, zygomatic and lacrimal nerves

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13
Q

Innervation of the lacrimal gland: postganglionic sympathetic fibers from the _______________ ganglion course on the internal carotid plexus, and give rise to the ____________ nerve which fuses with the _________________ nerve to form the _____________ nerve. Postganglionic fibers course thorugh the ______________ ganglion without synapsing and distribute to the lacrimal gland via the ___________________ nerve route.

A

Superior cervical ganglion; deep petrosal nerve; superficial petrosal nerve; Vidian nerve; sphenopalatine ganglion; maxillary-zygomatic-lacrimal nerve route

**some postganglionic sympathetic fibers may distribute to the gland via the lacrimal plexus n the adventitia of the lacrimal artery

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14
Q

Blow-out fractures to the floor of the orbit may be due to what? What do they cause?

A

May be due to trauma to the front of the eyeball or a depressed fracture of the zygomatic bone which is displaced medially

Cause herniation of certain structures into the maxillary sinus

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15
Q

Explain Le Forte Type I maxillary fracture classification

A

Transverse fractures of the maxillae just above the alveolar processes

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16
Q

Explain Le Forte Type II maxillary fracture classification

A

Pyramidal-shaped fractures of the maxillae usually involving part of the medial margin of one of the orbits

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17
Q

Explain Le Forte Type III (Craniofacial dysjunction) maxillary fracture classification

A

Extensive transverse fractures of the face involving many facial bones and both orbits (panda bear appearance). Basically, the face has been separated from the base of the skull

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18
Q

What are the 3 layers of fascia of the orbit?

A

Periorbita
Bulbar sheath
Muscular fascia

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19
Q

The periorbita fascia of the orbit is continuous with ________________. The bulbar sheath of the orbit is continuous with _______________.

A

Endosteal dura; meningeal dura

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20
Q

How can increased intracranial pressure affect the lateral rectus muscle of the eye?

A

It can compress the abducens nerve and result in paralysis of the lateral rectus muscle

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21
Q

What are cardinal signs of gaze testing and how do you perform the test?

A

Testing extraocular muscle function. You move your hand in an H pattern and have them follow you with their eyes

Note: straight up and down are not cardinal positions of gaze

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22
Q

What is the chief sensory nerve to the orbit?

A

Nasociliary nerve

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23
Q

*What Nerves are responsible for the afferent versus efferent portions of the corneal reflex?

A

Afferent = nasociliary nerve (V)

Efferent = Zygomatic branch of VII

24
Q

Explain the steps of the corneal reflex

A

1) Stimulus = light touching cornea
2) Receptors = naked nerve endings in cornea
3) Afferent fibers = nasociliary nerve, especially long ciliary nerves
4) Sensory nucleus = descending nucleus of V
5) Motor nucleus = facial nucleus
6) Efferent fibers = facial nerve
7) Effector = orbicularis oculi muscle
8) Response = blinking

25
Q

What is the chief artery of the orbit?

A

Ophthalmic artery -> usualy the first branch of the ICA

26
Q

What are the terminal branches of the ophthalmic artery?

A

Supratrochlear and dorsal nasal arteries

27
Q

The __________ artery gives rise to the posterior ciliary artery and central retinal arteries, both of which supply the _________ nerve

A

Ophthalmic artery; optic nerve

28
Q

What artery constitutes the main supply to the retina?

A

Central retinal a

29
Q

What is the arterial circle of Zinn-Haller?

A

An incomplete arterial circle formed at the junction of the optic nerve and globe of anastomosis of the central retinal and posterior ciliary arteries

30
Q

The central retinal artery supplies the 4 quadrants of the retina thorugh upper and lower ____________ branches and upper and lower __________ branches

A

Temporal; nasal

These are end arteries (no anastomosis available)

31
Q

Infections in the orbit can course into the cavernous sinus by way of the ________________ vein

A

Superior ophthalmic vein

32
Q

When you shine light in the right eye, you should see constriction of the left eye as well, this is consensual reflex. What structure is responsible for this?

A

Posterior commissure

33
Q

The lacrimal artery gives rise to the _______________ artery which anastomoses with the middle meningeal artery. The lacrimal or ophthalmic arteries may be branches of the _______________ artery.

A

Recurrent meningeal artery; middle meningeal artery

34
Q

The lacrimal artery terminates as the ________________ arteries, which branch into __________________ arteries. These terminate in the _________________ plexus.

A

Lateral palpebral arteries (2); posterior conjunctival arteries; superficial pericorneal plexus

35
Q

What does the supraorbital artery supply?

A

Upper eyelid and scalp

36
Q

What does the supratrochlear artery supply?

A

Medial portion of upper eyelid and scalp

37
Q

What does the anterior ethmoid artery supply?

A

Dura of the anterior cranial fossa, nasal cavity, and external nose

38
Q

The ______________ vein s formed by the supraorbital and angular veins and drains into the cavernous sinus

A

Superior ophthalmic vein

39
Q

Tributaries of the ophthalmic veins generally course with arteries of the same names. They communicate with the angular vein, pterygoid plexus and the _________________

A

Cavernous sinus

40
Q

What is the function of the ciliary muscles of the eye?

A

They decrease the tension on the ciliary zonular fibers, allowing the lens to thicken for near vision

41
Q

WHat s the pupillary dilation response?

A

A decrease in the amount of the light reaching the retina results in bilateral reflex dilation of the pupils. This sympathetic response is mediated thorugh the brainstem and upper spinal cord

42
Q

Interruption in the pupillary dilator reflex pathway results in what condition?

A

Horner’s syndrome

43
Q

The triad of accommodation for near vision includes what 3 responses?

A

Convergence (Bilateral contraction of medial recti ms) AKA dysconjugate gaze**

Pupillary constriction (contraction of sphincter pupillae muscles)**

Thickening of lens (relaxation of ciliary zonular fibers by ciliary muscles)

44
Q

Accommodating gaze and ision to view objects in the near field of vision is initiated in the cerebral cortex and mediated by what nerve?

A

Occulomotor

45
Q

What is the critical link in the direct light reflex?

A

Pretectum

46
Q

What is the critical link in the pupillary dilation reflex?

A

Preganglionic sympathetic neurons (ILCC at T1)

47
Q

Accommodation is a ____________-mediated response

A

Cortically

48
Q

What nerves are responsible fore the afferent and efferent components of the pupillary dilation reflex?

A

Afferent = Optic nerve (II)

Efferent = sympathetic branch of ciliary ganglion from superior cervical ganglion

49
Q

What are nerves are responsible for the afferent and efferent components of the direct light reflex?

A

Afferent = optic nerve (II)

Efferent = occulomotor nerve (III)

50
Q

Direct light reflex is a ____________-mediated response, whereas the pupillary dilation reflex is a ____________-mediated response

A

Parasympathetic; sympathetic

51
Q

____________ pupil is a condition where the pupils are accommodating but unreactive

A

Argyll-Robertson pupil

52
Q

What is Argyll-Robertson pupil?

A

A result of syphilis infection. Pupils are unreactive to light, but constrict during accommodation. Probably due to destruction of the pretectum,which is important in light reflex, but not in accommodation

53
Q

What is Holmes-Adie pupil (AKA tonic (Adie) pupil)?

A

Benign condition which may be due to a lesion of the ciliary ganglion. Initially, pupil doesnt appear to react to convergence but if its maintained for several seconds, the pupil will slowly constrict -> eventually the affected pupil may be smaller than the normal pupi

**More common in young adult females

54
Q

How can Holmes-adie pupil be treated with drugs?

A

Parasympathomimetic drugs -> constrict tonic pupil and have no effect on normal pupil

55
Q

What is papilledema due to?

A

Increased intracranial pressure frequently restricts venous return from the retina. The concomitant increase in venous pressure results in edema or swelling of the optic disc.

Increased intracranial pressure may also disrupt retrograde axonal flow, thereby causing the proximal portions of the fibers to swell

COM: Neuro (Exam I) (13 decks)

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