Anatomy Flashcards
Name the 7 bones of the orbit of the eye?
- frontal
- zygomatic
- maxilla
- nasal
- sphenoid
- ethmoid
- lacrimal
What are the 2 most common orbital plates to fracture?
- maxilla
- ethmoid
What cranial nerves pass through the superior orbital fissure?
- CN 3,4,6
The orbit of the eye can be described as pyramidal, where is the apex located?
- opening to optic canal
What is the axis of the eye ball?
- anterior
What is the axis of the orbit?
- anterolateral
What is transmitted in the optic canal?
- optic nerve
- ophthalmic artery
Explain a blowout fracture?
- medial wall and orbital floor
Explain an orbital rim fracture?
- higher impact injuries
- sutures joining fracture
What is the orbicularis oculi 2 components?
- orbital part
- palpebral part
LPS is a ____ muscle
- skeletal muscle
Lacrimal gland produces lacrimal fluid by what type of innervation?
- parasympathetic
- CN VII
Name the 4 rectus muscles?
- superior rectus
- inferior rectus
- medial rectus
- lateral rectus
Name the 2 oblique muscles?
- superior oblique
- inferior oblique
Where does the rectus muscle attach?
- originates common tendinous ring
- inserts onto sclera
Where does the superior oblique muscle originate?
- sphenoid bone
Where does the inferior oblique muscle originate?
- orbital plate of maxilla
What nemonic can be learn for orbital muscle innervation?
- LR6 SO4 AO3
Lateral rectus innervation?
- CN VI
Superior oblique innervation?
- CN IV
What muscle is responsible for tight closure of the eye?
- orbital part of the orbicularis oculi
What muscle is responsible for gentle closure of the eye?
- palpebral part of the orbicularis oculi
What innervates the superior tarsus muscle?
- sympathetic stimulation
Where is the lacrimal gland found?
- superolateral
Where does lacrimal fluid drain into?
- inferior nasal cavity
What are the 7 extraocular muscles?
- superior rectus
- inferior rectus
- medial rectus
- lateral rectus
- superior oblique
- inferior oblique
- levator palpebae superioris
What is another name for the corneoscleral junction?
- limbus
What are the 3 layers of the eye?
- fibrous
- uvea
- retina
The uvea layer of the eye is known as the?
- vascular layer
What separates the anterior and posterior segments?
- the lens
The anterior segment can be divided into_____ by the ____
- anterior chamber
- posterior chamber
- divided by the iris
What is found in the posterior segment of the eye?
- vitreous body
What secretes aqueous?
- ciliary body
When aqueous circulates in the posterior segment what is its role?
- nourishes the lens
When aqueous circulates in the anterior segment what is its role?
- nourishes cornea
Where is aqueous reabsorbed?
- iridocorneal angle
What is the major arterial blood supply to the eye?
- ophthalmic artery, branch of internal carotid
How does the internal carotid reach the eye?
- through the carotid canal
What is the major end artery in the eye?
- central artery of the retina
Venous drainage of the eye drains where?
- cavernous sinus
Explain the optic disk?
- point of CN II formation
- only point of entry and exit of blood vessels
- blind spot, no photoreceptors
Where is the greatest density of cones found?
- macula
What is the centre of the macula known as?
- fovea
Where is the area of the retina with the most acute vision?
- fovea
What are the layers of the retina from posterior to anterior?
- photoreceptors
- ganglion cells
- axons of ganglion cells
Axons in the eye come together to form what?
- optic nerve
- no photoreceptors
Interruption of a branch of the retinal artery ca lead to what?
- loss of an area of visual field corresponding to the area of ischaemia
Interruption of the central artery in the eye leads to?
- monocular blindness
- as it is an end artery
Light from objects in the right visual field are processed where?
- left visual cortex
Light from lower visual fields is processed where?
- upper part of the primary visual cortex
What crosses over at the optic chiasma?
- nasal retina
vertical axis movement causes?
- abduction and adduction
transverse axis movement causes?
- elevation and depression
anteroposterior axis movement causes?
- intorsion and extorsion
lateral rectus is under what cranial nerve’s control?
- CN VI
Superior oblique is under what cranial nerve’s control
- CN IV
Lateral rectus can only ___ the eyeball
- abduct
Superior rectus when in abduction can only _____ the eye ball
- elevate
Inferior rectus when in abduction can only _____ the eye ball
- depress
Medial rectus ___ the eyeball
- adducts
Inferior oblique when in adduction causes ____
- elevation
Superior oblique when in adduction only causes ___
- depression
Where does the sympathetic nerves exit the spinal cord?
- T1- L2
Where do sympathetic nerves synapse?
- superior cervical sympathetic ganglion
Where does the parasympathetic nerves leave the CNS?
- CN III, VII, IX, X
- Sacral spinal nerves
Where do the ocular parasympathetic nerves synapse?
- ciliary ganglion
Where does CN III exit?
- superior orbital fissure
What is the smooth muscle component of the LPS?
- Muller’s muscle
- involuntary
What are the 3 divisions of the trigeminal nerve?
- CNV1 = Ophthalmic
- CN V2 = Maxillary
- CN V3 = Mandibular
Explain the corneal reflex?
- blink
- sensory afferent CN V1 (ophthalmic)
- motor efferent CN VII (Facial)
What is the vestibulo-ocular reflex?
- eyes fix gaze when head moves
- head and eyes move in opposite direction
Explain the oculocardiac reflex
- reflex bradycardia in response to tension on extraocular muscles or pressure on eye
What is the sympathetic response effect on eye?
- eyes get wider
- focus on further objects
- emotional lacrimation
Explain the parasympathetic response effect on the eye?
- less light into eye
- focus on nearer objects
- reflex lacrimation
What muscle is responsible for opening the eye wider?
- levator palpebrae superiors
What is the iris composed of?
- inner sphincter pupillae muscle
- outer dilator pupillae muscle
Explain the effect of the inner sphincter pupillae muscle?
- when contracted eye allows less light in
- constriction
Explain the effect of the dilator pupillae muscle?
- mobile attachment in middle, dilates eye
Mitotic pupil?
- non-physiological constriction
Mydriatric pupil?
- non-physiological dilation
Muscle responsible for pupil constriction?
- sphincter pupillae
Muscle responsible for pupil dilation?
- dilator pupillae
Explain pupillary light reflex
- sensory is ipsilateral CN II
- Motor is bilateral CN III
What is responsible for lens accommodation?
- suspensory ligament of the ciliary body
Explain the ciliary body?
- both muscular and vascular components
- suspensory ligaments control the shape of the lens
What is the shape of the lens for distance objects?
- lens flattens
- ligaments tighten
What is the shape of the lens for near objects?
- spherical
- ligaments relax
What are the 3 types of tears?
- basal
- reflex
- emotional
What is the function of basal tears?
- corneal health
- clean and nourishment
- lysozyme
What is the function of the meninges?
- protective coverings of the brain and the spinal cord
What are the 3 meninges from exterior to interior?
- dura mater
- arachnoid mater
- pia matter
What lies between the arachnoid mater and the Pia mater?
- subarachnoid space
What is the sensory innervation to the dura mater?
- CN V
What is found in the arachnid space and is responsible for the drainage of CSF?
- Arachnoid granulation
What meninges layer adheres to the brain?
- Pia mater
What level should a lumbar puncture be performed?
- L3/4
- L4/5
Where does the subarachnoid space end?
- Vertebral level S2
What is the Monro-kellie hypothesis?
- the volume of brain, blood and CSF is constant
What is unique about the optic nerve?
- it is covered by meninges
- meaning it has a subarachnoid space
What is the affect of a raised ICP on the optic nerve?
- transmitted along the optic nerve in subarachnoid space
- can compress the nerve
What is the clinical condition that describes compression of the optic nerve?
- papiloedema
What is the dural septae?
- folds of dura mater
- falx cerebri
- tentorium cerebelli
- falx cerebelli
- diaphragma sellae
What lobe is responsible for compression of the oculomotor nerve?
- medial temporal lobe herniation
What is the clinical signs of a compressed oculomotor nerve?
- dilated pupil (loss of parasympathetic innervation)
- turned inferolateral
What is the clinical signs of a compressed trochlear nerve?
- paralysis of superior oblique
- eye cannot move inferomedially
Define diplopia?
- double vision
What is the clinical signs of a compressed abducent nerve?
- paralysis of lateral rectus muscle
- medial deviation of the eye
