Anatomy Flashcards
what is the orbit
the various bones surrounding the eyeball
list the external bones of the orbit
frontal
zygomatic
maxilla
list the internal bones of the orbit
sphenoid
ethmoid
lacrimal
what structure is the roof of the orbit
sphenoid bone
what bones form the floor of the orbit
maxilla
zygomatic
palatine
what bones form the medial wall of the orbit
maxilla
sphenoid
ethmoid
lacrimal
what bones form the lateral wall of the orbit
zygomatic
what structures are contained in the orbit
eyeballs eyelids extra-ocular muscles blood vessels nerves
what are the three holes that structures can enter and exit the orbit
optic canal
superior orbital fissure
inferior orbital fissure
what structures pass through the optic canal
optic nerve and ophthalmic artery
what structures pass through the superior orbital fissure
lacrimal, frontal, trochlear, oculomotor and abducen nerve
what structures pass through the inferior orbital fissure
inferior ophthalmic nerve
zygomatic branch of maxillary nerve
sympathetic nerve
describe a blowout fracture
direct blunt force trauma to the orbit causing partial herniation of the orbital content through one of its walls
what are the 3 layers of the eye
outer/fibrous layer
vascular layer
inner layer
what are the two components that make up the fibrous layer of the eye
cornea
sclera
where is the cornea located
centrally in the eye over iris and pupil
what is the function of the cornea
2/3 of refractive power
outermost lens of the eye
where is the sclera located
around the periphery of the eye/white region
what is the function of the sclera
muscle attachment point of extra-ocular muscles
what is the vascular layer of the eye also known as
uvea
what are the three structures within the uvea
iris
ciliary body
choroid
what is the function of the iris
controls the diameter of the pupil by smooth muscle fibres innervated by autonomic nervous system
what is the function of the ciliary body
the ciliary body controls the shape of the lens by contraction of the ciliary muscles
also contributes to formation of aqueous humour
what is the function of the choroid
collection of connective tissue and blood vessels providing nutrients to the retina
what is the inner layer of the eye formed by
the retina - light detecting component
what are the two segments of the eye called
anterior and posterior segment
where is the anterior segment located
in front of the lens of the eye
this is divided into anterior and posterior chambers
where is the posterior segment located
behind the lens of the eye
contains vitreous body made up of vitreous humour
what is the main blood supply to the eye
ophthalmic artery
which artery is the ophthalmic artery derived from
internal carotid artery
describe the venous drainage of the eye
mainly the superior and inferior ophthalmic vein
the orbit drains anteriorly to the facial vein
what is the centre of the retina called
macula
the macula has the greatest density of what cells
cones
what is the centre of the macula called
fovea - this is the area of most acute vision
list the extraocular muscles
levator palpebrae superioris lateral rectus medial rectus inferior oblique superior oblique inferior rectus superior rectus
which muscle is involved in raising the superior eyelid
levator palpebrae superioris
where does LPS attach
lesser wing of the sphenoid bone
which nerve innervates LPS
oculomotor nerve CN III
the rectus muscle have a direct or angular approach to the eye
direct
what is the action of superior rectus
when abducted can only elevate
what nerve innervates the superior rectus muscle
CN III
what is the action of inferior rectus
when adducted can only depress
which nerve innervates the inferior rectus muscle
CN III
what is the action of the medial rectus
adduction only
what nerve innervates the medial rectus
CN III
what is the action of the lateral rectus
abduction only
what nerve innervates the lateral rectus muscle
CN VI
where do the oblique muscles attach
posterior surface of the sclera
what is the action of the superior oblique
when adducted can only depress
what nerve innervates the superior oblique
CN IV
what is the action of the inferior oblique
when adducted can only elevate
what nerve innervates the inferior oblique
CN III
how would an oculomotor nerve lesion present
the affected eye positioned in a down and out way as the only functioning muscles are LR and SO
how would a trochlear nerve lesion present
no obvious difference in orientation of the eyeball
however patient will complain of double vision when walking down the stairs and will compensate by tilting head to one side
how would an abducens nerve lesion present
the resting eye will be adducted because the lateral rectus is not longer working
what causes Horners Syndrome to arise
damage to the sympathetic trunk
what are the clinical symptoms of Horners Syndrome
partial ptosis - drooping of eyelid due to innervation of superior tarsal muscle
miosis - pupillary constriction
anhidrosis - absence of sweating on ipsilateral side due to denervation of sweat glands
what disease cause Horner’s syndrome to arise
Pancoast tumour
aortic aneurysm
thyroid carcinoma
which muscle controls the closing of the eyelids and the lacrimal duct
orbicularis oculi
describe the three parts of the orbicularis oculi and their functions
palpebral - gently closes the eyelids
orbital - tightly closes the eyelids
lacrimal - involved in drainage of tears
which cranial nerve innervates the orbicularis oculi
CN VII facial nerve
the orbicularis oculi is the most superficial or deep part of the eyelid
superficial
which cranial nerve innervates the lacrimal gland
CN VII
where is the lacrimal gland located
superolateral aspect of the eye in a fossa within the frontal bone
after the optic chiasm, vision from the temporal or nasal side stays at the same side
temporal stays the same, the nasal vision crosses over at the optic chiasm
when vision is observed through the eyes, list the structures it passes through to get to the brain
optic nerve
optic chiasm, cross over
optic tracts
optic radiation
where is the optic radiation located
in the visual cortex within the occipital lobe
light from the right visual cortex is processed in the right/left primary cortex
left
light from the lower visual field is processed in the upper/lower primary cortex
upper
which cranial nerve supplies sensory innervation to the face
CN V
which parts of the face does CN V1 supply
upper eyelid
cornea
conjunctiva
which part of the face does CN V2 supply
skin of lower eyelid
skin over maxilla
which part of the face does CN V3 supply
skin over mandible
TMJ
which cranial nerve carries the sensory (afferent) limb of the blinking reflex
CN V1
which cranial nerve carries the motor (efferent) limb of the blinking reflex
CN VII to the orbicularis oculi
sympathetic is fight and flight or rest and digest
fight or flight
sympathetic innervation is responsible for what changes in the eye
open eyes wider to get more light in
emotional lacrimation
parasympathetic innervation is responsible for what changes in the eye
less light in to protect the retina - focus on nearby objects
parasympathetics constrict the pupil in bright light
state the cranial nerves involves in the sensory and motor limb of the pupillary light reflex
sensory - CN II ipsilateral
motor - CN III bilateral
state the nucleus of the brain involved in the pupillary light reflex
Edinger-Westphal nucleus
in the lens accommodation reflex the ciliary muscles __ the ligament ___ and the lens ___
relax
tighten
flattens - enables the object in the distance to be seen
in the lens accommodation reflex the ciliary muscles ___ the ligament __ and the lens ___
contract
relax
becomes more spherical to see near object
what type of vision do cones produce
coloured vision
what type of vision do rods produce
black/dim vision
which muscle of the eye is most likely to be damaged after a blowout fracture
inferior rectus
