The Eye Flashcards
What are the structures forming the roof of the orbit?
The frontal bone and the lesser wing of the spenoid
What are the structures forming the lateral wall of the orbit?
The zygomatic and the spenoid bone.
What are the the structures forming the floor of the orbit?
The maxillary and the zygomatic bones
What are the structures forming the medial wall of the orbit?
Ethmoid, the maxillary, the lacrimal and the spenoid bones
What structures pass through the optic canal?
The optic nerve and the opthalmic atery
What structures pass through the superior orbital fissure?
Transmit the lacrimal, frontal, trochlea, occulomtors, nasociliary and abducens nerves, and contains the superior opthalmic vein
Whihc structures run through the inferior orbital fissure?
The maxillay nerve, the opthalmic nerve and the sympatheic veins
What are some of the features of a orbital rim fracture?
A fracture of the bones from the outer rim of the bony orbit, usually occures at the sutures joining the three bones- the maxilla, the zygomatic and the frontal bone
What are some of the features of a blowout fracture?
Refers to the partial herniation of the orbital contents through one of the walls, usaully occurs through blunt force or trauma to the eye, and the medial and inferior walls are the weakest with the contents most likley to herniate through, and contents hernaitin into the ethomodi and maxillary sinuses.
Which muscle can be trapped in a blowout fracture?
The inferior rectus muscle can become stuck
What are the structures found in the fibrous layer of the eyeball?
The outermost layer that contians the scelra and the cornea
What are some of the features of the scelera?
The majority of the fibrous layer and provides attachement to the extra- ocular muscles
What are some of the features of the cornea?
Is transparent and located centrally within the eye, and light entering the eyes is refracted by the cornea
What is the choroid?
A ;ayer of connective tissue and blood vessel that provides nourishment to the outer layers of the eye
What is the ciliary body?
Is comprised of two parts the ciliary muscles and the ciliary processes, the ciliary muscle is a collection of smooth muscle fibres that are attached to the lens of the eye by the ciliary processes, and the ciliary body controls the shape of the lens, and also contributes to the formation of an aqueous humour
What is the iris?
A circular structure, wiht an apeture in the centre, and the diameter of the pupil is alteres by the smooth muscle fibres whithin the iris, and innervated by the autonomic nervous system and is situated between the lens and the cornea
What are the two inner layers of the eye?
The neural layer that consists of the photrreceptros, and the pidmenation layer that lies underneath the neural layer and is attached to the chorioid layer
What is the macula?
Is an area at the centre of the retina containing a depression called the fovea, which has a high concentration of light detecting cells, and is where the highest acuity vision occurs
What is the optic disc?
An area where the optic nerve enters the retina, and has no light detecting cells within this area
What is papillodema?
Swelling of the optic disk, the is visible using a opthalmoscope
What are the causes of papillodema?
Swelling occurs secondary to raised intercranial pressure, and the high pressure in the cranium resists the venous return from the eye and causes fluid to collect in the retina
What is retinal detachement?
A detachment results from a seepage of fluid between the nearla and pigament cell layers, which can occur for days or weeks after a trauma, and the paitent may complain of flashes of light or specks floating in front of the eye
Where is the anterior chamber of the eye located?
Is located between the cornea and the iris
Where is the posterior chamber of the eye located?
Between the iris and the ciliary proccess
What are some of the features of aqueous humour?
Is produced constantly and drains via the traebecular meshwork, an area of tissue at the base of the conrea.
What is a open angle glucoma?
Where the outflow of aqueous humour through the traebecular meshqoek is reduced, and this causes a gradual reduction in vision until the end stage of the disease
What is a closed angle glucoma?
Where the iris is forced agaisnt the traebecular meshwork, preventing any drainge of aqueous humour, is an opthamlic emergency as it can rapidly lead to blindness
What is a catract?
A loss of transpency an increase in cloudiness of the lens
What is the extraocular muscle supplied by the abducens nerve?
The lateral rectus
What is the extraocular muscle supplied by the trochlear nerve?
The superior oblique
What are the extraocular muscles supplied the occulomotor nerve?
The superior rectus, inferior rectus and medial rectus, the inferior oblique and the levator palprae superiorus
Where do the msucles of the eye (apart from the obliques) oringate from?
A common tendinous rin
Where do the extraocular muscles attach?
The sclera
What are the sympatheic fibres in the eyelid called?
The superior tarsal muscle
What is the function of the superior oblique?
To enable the eye to look down medially
What is the function of the inferior oblqique?
To help a person to look upwards medially
What is the most important atery in supplying blood to the eye and from where does it arise?
The central atery of the retina, which arise s from the the opthalmic atery which is a branch of the internal cartoid that arises immeadatly distal to the cavernous sinus
What is the clincal importance of a central retinal atery occulsion?
Will quickly result in blindness, and is a end atery, and you will usually see a cherry red spot on a pale background
Where does the central retinal vein drain?
Into the superior opathalmic vein, which drains into the cavernous sinus
What are the clincal features of a central retinal vein occulsion?
Because the central vein of the retina enters the cavernous sinus, and theroemplitis of sinus can result in passage to the central retinal vein and then cause an occulision
What are the nerve lesions that result in complete and partial ptsois?
Complete ptosis results from a CNIII lesion whereas partial ptosis results from a sympatheic lesion
