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Anatomy > Orbit and the eye > Flashcards

Orbit and the eye Flashcards

1
Q

Which bones make up the orbit ?

A
  • frontal bone
  • zygomatic bone
  • maxilla
  • nasal bone
  • sphenoid bone
  • ethmoid bone
  • lacrimal bone
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2
Q

What is the function of the eyelids ?

A
  • protect the eyes
  • eyelashes prevent dust and particles from entering the eyes
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3
Q

What are the different components of the eyelids ?

A
  • outer skin
  • inner conjunctiva (inner mucous membrane)
  • eyelashes
  • glands
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4
Q

Summarise the structure and function of the tarsal plates

A
  • made of dense connective tissue
  • they maintain the shape of the eyelids
  • contain tarsal glands which secrete an oily substance
  • each eyelid contains 1 tarsal plate so there are 4 tarsal plates in total
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5
Q

What is the function of the oily substance secreted by the tarsal glands ?

A
  • lubricates the eyelid so they don’t stick together
  • prevents the quick evaporation of tears
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6
Q

What are the muscles found in the eyelid ?

A
  • orbicularis oculi
  • superior tarsal muscles
  • levator palpebrae superioris
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7
Q

Describe the function and innervation of the muscles found in the eyelid

A
  • orbicularis oculi is a muscle of facial expression and it is supplied by the facial nerve
  • levator palpebrae superioris is a skeletal muscle supplied by the oculomotor nerve
  • superior tarsal muscle is a smooth muscle supplied by the sympathetic nervous system
  • both of these muscles elevate the eyelid
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8
Q

What are the 2 parts of the orbicularis oculi muscle and where are they found ?

A
  • orbital part : surrounds the orbital margin
  • palpebral part : found within the eyelid
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9
Q

What is the orbital septum ?

A

It is a fibrous membrane which extends outwards to cover the gap in the orbit

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10
Q

How are the tarsal plates connected to the orbital margin ?

A
  • connected to the medial margin of the orbit by the medial palpebral ligament
  • connected to the lateral margin of the orbit by the lateral palpebral ligament
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11
Q

Where are the tarsal plates found in relation to the muscle ?

A

they are found deep to the palpebral part of the orbicularis oculi muscle

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12
Q

What is the function of the lacrimal apparatus ?

A

involved in the production, movement and drainage of tears

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13
Q

Describe the pathway of the tears

A

1) tears are produced in the lacrimal gland
2) they travel through lacrimal gland ducts across the cornea
3) they enter the lacrimal puncta which are openings in the eyelids
4) they then travel through the lacrimal canaliculi which are tubes
5) enter the lacrimal sac
6) through the nasolacrimal duct
7) into the inferior meatus of the lateral wall of the nasal cavity

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14
Q

Where is the lacrimal gland located ?

A

it is located superior and laterally in the orbit

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15
Q

What is the sensory innervation of the lacrimal gland ?

A

innervated by the lacrimal nerve which is a branch of the ophthalmic division of the trigeminal nerve

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16
Q

What is the secretomotor (parasympathetic) innervation of the lacrimal gland ?

A

it is very complex so look at lecture

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17
Q

What is the sympathetic innervation of the lacrimal gland ?

A

the sympathetic innervation of the lacrimal gland is from fibres of the superior cervical ganglion but it is only involved in vasoconstriction of blood vessels in the area

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18
Q

What does the lacrimal nerve supply ?

A
  • sensory innervation to the lacrimal gland
  • sensory innervation to the skin and fascia of of the lateral aspect of the upper eyelid
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19
Q

What does the external nasal nerve supply ?

A
  • supplies skin on the dorsum and lateral aspect of the nose
20
Q

What are the extrinsic muscles of the eye ?

A
  • lateral rectus
  • medial rectus
  • inferior rectus
  • superior rectus
  • inferior oblique
  • superior oblique
21
Q

What is the general functions of the extrinsic (extraocular) muscles of the eye ?

A

they move the eyeballs

22
Q

What is the trochlea ?

A

It is a cartilaginous component which contains the tendon of the superior oblique muscle

23
Q

What is the position of the superior oblique muscle in relation to the medial rectus muscle ?

A

The superior oblique muscle lies superior to the medial rectus

24
Q

Describe the action of the lateral rectus muscle

A

abduction - lateral movement of eyeball

25
Q

Describe the action of the medial rectus muscle

A

adduction - medial movement of the eyeball

26
Q

Describe the action of the superior rectus muscle

A

elevation - upwards and inwards movement of eyeball

27
Q

Describe the action of the inferior rectus muscle

A

depression - downwards and inwards movement of eyeball

28
Q

Describe the action of the superior oblique muscle

A

depression - downwards and outwards movement of eyeball

29
Q

Describe the action of the inferior oblique muscle

A

elevation - upwards and outwards movement of eyeball

30
Q

Describe the innervation of the extraocular muscles of the eye

A
  • lateral rectus = abducent nerve
  • superior oblique = trochlear nerve
  • superior rectus, medial rectus, inferior rectus and inferior oblique = oculomotor nerve
31
Q

What are the intrinsic eye muscles ?

A
  • sphincter pupillae
  • dilator pupillae
  • ciliary muscles
32
Q

Where are the intrinsic muscles of the eye found ?

A

in the eyelid

33
Q

What is the function and innervation of the sphincter pupillae muscle ?

A
  • when it contracts it will constrict the pupil
  • innervated by the parasympathetic component of the oculomotor nerve
34
Q

What is the function and innervation of the dilator pupillae muscle ?

A
  • when it contracts it will dilate the pupil
  • innervated by the sympathetic component of the oculomotor nerve
35
Q

What is the function and innervation of the ciliary muscles ?

A
  • they form a circular ring which surrounds the lens
  • the lens is suspended to the muscles by suspensory ligaments
  • innervated by the parasympathetic component of the oculomotor nerve
36
Q

Describe what happens when there is no nerve stimulation to the ciliary muscles

A
  • ciliary muscles will relax
  • the circular ring will get bigger
  • the ligaments become tense
  • lens becomes thinner
  • eye will focus on a distant object
37
Q

Describe what happens when the ciliary muscles have parasympathetic stimulation

A
  • ciliary muscles will contract
  • the circular ring will get smaller
  • the ligaments become relaxed
  • lens becomes thicker
  • eye will focus on a near object
  • this process is known as accommodation
38
Q

Describe the ciliary ganglion

A
  • it is a collection of neuronal bodies found between the optic nerve and lateral rectus muscle
  • it contains the preganglionic parasympathetic fibres of the oculomotor nerve and the postganglionic parasympathetic fibres of the short ciliary nerves
39
Q

What is the function of the short ciliary nerves ?

A

they innervate the sphincter pupillary muscles and ciliary muscles

40
Q

Describe the ophthalmic artery

A
  • it is a branch of the internal carotid artery
  • travels with the optic nerve through the optic canal
41
Q

Describe the central retinal artery

A
  • it pierces the optic nerve and travels in the middle of the optic nerve to supply the retina
42
Q

Describe the ophthalmic veins

A
  • there is a superior and inferior ophthalmic vein
  • they travel through the superior orbital fissure
  • they drain into the cavernous sinus
  • they anastomose with the angular vein of the facial vein
43
Q

Describe the location of the lacrimal nerve

A

it sits on top of the lateral rectus muscle

44
Q

Describe the location of the frontal nerve

A

it sits on top of the levator palpebrae superioris

45
Q

Where is the superior rectus muscle found in relation to the levator palpebrae superioris ?

A

the superior rectus is found below the the levator palpebrae superioris

Anatomy (10 decks)

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