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Head and Neck > Lecture 10 Eye Muscles > Flashcards

Lecture 10 Eye Muscles Flashcards

1
Q

What do the intrinsic ocular muscles control

A

control pupil diameter & helps alter lens curvature to enable us to see near objects

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2
Q

What do the extrinsic ocular muscles do (extra ocular)

A

Move the eye

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3
Q

How many extra ocular muscles are there

A

6

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4
Q

Name the extra ocular muscles

A 
Superior rectus
Inferior rectus
Lateral rectus
Medial rectus
Superior oblique
Inferior oblique
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5
Q

Where do the recti muscles arise from

A

Arise from the orbit from an annular fibrous ring

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6
Q

Where does the superior oblique muscle arise from

A

Roof of the orbit posteriorly

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7
Q

Where does the inferior oblique muscle arise from

A

Floor of the orbit anteriorly

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8
Q

Where does the elevator palpebral superiors lie and what is its purpose

A

Just above the superior rectus and elevates the eyelid

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9
Q

Where do the rectify muscles insert into the sclera

A

Anterioirly

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10
Q

Where do the oblique muscles insert into the sclera

A

Posteriorly

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11
Q

What are the muscles in the face that close the eyelids

A

Orbicularis oculi

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12
Q

What are the 2 parts of the orbicularis oculi

A

orbital and palpebral sections

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13
Q

Where does the orbicularis oculi arise from

A

It arises from the nasal part of the frontal bone, from the frontal process of the maxilla in front of the lacrimal groove, and from the anterior surface and borders of a short fibrous band, the medial palpebral ligament

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14
Q

Define uniocular

A

Movement of one eye

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15
Q

Define binocular

A

Movement of two eyes

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16
Q

Define intorsion

A

When the top of the eyeball rotates towards the nose

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17
Q

Define Extorsion

A

When the top of the eyeball rotates away from the nose

18
Q

What is the action of the medial rectus

A

Adduction

19
Q

What is the action of the lateral rectus

A

Abduction

20
Q

What are the actions of the superior rectus

A

Elevation
Adduction
Intorsion

21
Q

What are the actions of the inferior rectus

A

Depression
Adduction
Extorsion

22
Q

What are the actions of the superior oblique

A

Intorsion
Depression
Abduction

23
Q

What are the actions of the inferior oblique

A

Extorsion
Elevation
Abduction

24
Q

Why do extra ocular muscles except for the medial and lateral rectus have more than one action

A

due to the angle they make with the optical axis of the eye while inserting into the eyeball.

25
Q

Why do the muscles pull the eyeball at an angle

A

The muscles are attached to the orbital axis not the optical axis

26
Q

What muscle is the only elevator of the abducted eye

A

Superior rectus

27
Q

What is Strabismus

A

Squint (misalignment of the eyes)

28
Q

What are the 2 types of Strabismus

A
  • Esotropia (manifest convergent squint)

* Exotropia (manifest divergent squint)

29
Q

What are the functional consequences of a squint

A

Amblyopia (brain surpasses the image of one eye)

Diplopia (nerve palsies)

30
Q

Name the intrinsic muscles in the eye

A

Ciliaris
Sphincter Pupillae
Dilator Pupillae

31
Q

What innervation of the intrinsic muscles

A

Ciliaris- parasympathetic (oculomotor, ciliary ggl.)
Sphincter- parasympathetic (oculomotor, ciliary ggl.)
Dilator- sympathetic. (T1, sup, cervical ggl.)

32
Q

What happens to the pupils in increased illumination

A

Both pupils constrict

33
Q

What happens to pupils in decreased illumination

A

Pupils dilate

34
Q

Fibres destined to activate the pupillary reflex go where after the optic tract (afferent pathway)

A

Do not go to the LGB instead leave optic tract to go the midbrain (where IIIn nucleus is situated) Edinger-Westphal nucleus

35
Q

Describe the efferent pathway of the light reflex

A

From EWN in IIIn nucleus, preganglionic parasympathetic pass through IIIn into orbit.
Parasympathetic fibres go to & synapse in ciliary ganglion.
Postganglionic fibres go through short ciliary nerves to constrictor pupillae

36
Q

What is the LGB

A

Lateral Geniculate Nucleus
A relay centre in the thalamus for the visual pathway.
Receives major sensory input from the retina

37
Q

What condition can cause pupil abnormalities

A

Horner’s Syndrome- pupils look different sizes anisocoria

38
Q

What are some common causes of absent/abnormal pupillary reflex

A
  • Any abnormality of the afferent limb/ centre / efferent limb of the reflex
  • Diseases of the retina – detachment/ degenerations or dystrophies
  • Diseases of the optic nerve – such as in optic neuritis (frequently seen in MS)
  • Diseases of the III cranial nerve (efferent limb)
39
Q

What is the afferent limb of the pupillary reflex made of

A

Retina, opic nerve, IIIn nucleus (EWN)

40
Q

What is the efferent limb of the pupillary reflex made of

A

IIIn nucleus (EWN), ciliary ganglion, ciliary sphincter muscle

41
Q

What innervation is damaged in Horner’s syndrome and what is the consequence

A

Sympathetic innervation

Affected pupil cannot dilate so is constricted

42
Q

Horner’s syndrome can occur due to the disruption of

A
  • Thoracolumbar outflow of the sympathetic
  • Sympathetic chain and cervical ganglia
  • Head and neck – postganglionic sympathetic fibres travel along with blood vessels
  • E.g. Pancoast tumour of the lungs

Head and Neck (16 decks)

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