The eye and sight Flashcards
bones contributing to the orbit framework
Superior wall: Frontal bone; lesser wing of sphenoid bone
Medial wall: Maxilla; Lacrimal; Ethmoid; lesser wing of sphenoid bone
Inferior wall: Maxilla; Zygomatic and Palatine bones
Lateral wall: Zygomatic (anteriorly); Greater wing of sphenoid (posteriorly)
2 groups of muscles within the orbit
Extrinsic / extra-ocular muscles - move eyeballs or raise upper eyelids
Intrinsic muscles - within eyeball - control shape of lens and size of pupil
The muscle above the superior rectus
Levator Palpaberae Superioris
Orbicularis Oculi
Not extrinsic muscle of eye
has two parts:
Orbital part - surrounds orbit, involved when eye tightly closed
Palpebral part - the eyelid, involve when eye gently closed
Muscles supplied by oculomotor nerve (3)
Superior rectus, Inferior rectus, Medial rectus, Inferior Oblique
LPS (levator palpebrae superioris)
Muscles supplied by abducens nerve (6)
Lateral rectus
Muscles supplied by trochlear nerve (4)
Superior Oblique
Eye movement caused by the: Lateral rectus
abduction
Eye movement caused by the: Medial rectus
Adduction
Eye movement caused by the: Superior rectus
Up and in (adduction)
Eye movement caused by the: Inferior rectus
Down and in (adduction)
Eye movement caused by the: Superior Oblique
Down and out (abduction)
Eye movement caused by the: Inferior Oblique
Up and out (abduction)
Clinical testing for: Lateral rectus
Ask to abduct eye
Clinical testing for: Medial rectus
Ask to adduct eye
Clinical testing for: Superior rectus
Ask to first abduct eye (out), then look down
Clinical testing for: Inferior rectus
Ask to first abduct eye (out), then look up
Clinical testing for: Superior oblique
Ask to first adduct eye (in), then look down
Clinical testing for: Inferior oblique
Ask to first adduct eye (in), then look up
Innervation of Levator Palpebrae Superioris
Oculomotor and sympathetic innervation
Sympathetic loss to LPS and oculomotor loss
Sympathetic loss - ptosis
Oculomotor loss - closed eyelid
Arterial supply to the orbit and eyeball
Ophthalmic artery - branch of the internal carotid artery immediately after it leaves the cavernous sinus
Ophthalmic artery passes into the orbit via the…with….
via the optic canal with the optic nerve
Name the nerves and vessels passing through the optic canal
Optic nerve
Ophthalmic artery
Name the nerves and vessels passing through the superior orbital fissure
Oculomotor nerve (3) Trochlear nerve (4) Ophthalmic division of the trigeminal nerve (V1) Abducens nerve (6) Ophthalmic veins Sympathetic fibres
Name the nerves and vessels passing through the inferior orbital fissure
Maxillary division of the trigeminal nerve (V2)
Inferior ophthalmic vein
Infraorbital vessels
Explain the clinical significance of the close relationship between the superior orbital fissure and the cavernous sinus
The superior ophthalmic veins drain into the cavernous sinus through the superior orbital fissure
Provides a potential route for infection from the orbit and nasal sinuses
This can lead to a cavernous sinus thrombosis
Describe the corneal/ pupillary reflex
1) Photoreceptors detect light. Optic nerve –> pretectal nucleus
2) –> the Edinger-Westphal nucleus
3) Motor signal –> oculomotor nerves –> ciliary ganglia
4) –> Parasympathetic innervation of the pupillary sphincter –> constriction of the pupil
Testing reflex: shine light in 1 eye.
Constriction in tested eye means:
Contraction in other eye means:
Tested eye: Good optic nerve function
Other eye : Good oculomotor nerve function
Branches of V1 (ophthalmic nerve of trigeminal)
Fine Looking Nipples
Frontal Nerve
Lacrimal Nerve
Nasociliary Nerve
What stimulation by what fibres causes fluid secretion from the lacrimal gland?
Parasympathetic stimulation by secretomotor fibres
Ducts from the lacrimal gland open into the
which empties over the
Conjunctival sac which empties over the eyeball
Tear drainage
Tears pass medially over the surface
- -> puncta and lacrimal canaliculi
- -> collect in the lacrimal sac
- -> lacrimal duct
- -> Internal meatus of nasal cavity
