Anatomy Flashcards
What are the 3 layers and their constituents
Fibrous tunic - sclera and cornea
Vascular - Iris, ciliary body, choroid
Retina - pigment and neuro
What accumulates in the sclera
Bilirubin
How many layers of sclera
3 - episcelra, sclera proper (collagen) and lamina fusca (pigment)
How many bones in orbital wall
7
Floor?
Maxilla, palatine and zygomatic
What makes the roof
Frontal and lesser wing of sphenoid
Medial wall?
Ethmoid, maxillary and sphenoid
Lateral wall?
Zygomatic, greater wing of sphenoid
What are the holes there?
Optic canal, greater and lesser orbital fissure
Which is the thinnest part of the orbital wall?
Medial orbital , but is strengthened by the ethmoid sinuses
Which is the most vulnerable part?
Floor - blow out fracture
What can you see in a blow out fracture
Down and depressed gaze, cannot look up due to Inferior recurs dysfunction
What is below the skin eyelid?
Orbicularis occuli - helps eyelid closure and release lacrimal gland secretion
Which nerve is it innervated by
Facial nerve (7)
What is the next layer?
Orbital septum
What is the grading used for orbital cellulitis
Chandlers
What’s next
Superior and inferior tarsal plates
What is in these plates and what do they do
Melbomian glands and they produce the lipid layers of the tears
What’s next
Levator apparatus
What are they innervated by
CN 3
What does this have
The superior and inferior tarsal muscles and levator palpabrae superioris
What happens in complete ptosis
Paralysis of the levator palpabrae superioris due to lesion in cn 3 (in the cavernous sinus due to vascular aneurysm)
What happens in partial ptosis
Paralysis of superior tarsal muscle which is innervated by sympathetic chain - Horners syndrome
Where do the punctums drain into?
Canaliculi
What does the common cancaliculi form?
Lacrimal sac
Where does that drain?
Nasolacrimal duct, which drains into turbunates
What are the layers of the cornea?
Anterior epithelium
Bowman’s membrane
Corneal stroma - regular collagen fibers - no vasculature, but well innervated
Descemet’s membrane
Endothelium - involved in fluid and ion balance - this is lost in corneal dystrophy leading to corneal opacity
What are the glands on the conjunctiva called?
Krause and Wolfring
What are the 3 segments of the conjucntiva
bulbar, fornix and palpebral
What kind of anesthetic can be injected
Sub tenon block on the tenon capsule in the conjunctiva for cataract surgery
What are the branches of the aorta
Aortic arch
Brachiocephalic trunk on the right
Common carotid on the left - breaks into internal and external carotid arteries
Subclavian on the left
What are the branches of the external carotid artery
8 branches - Some ancient lovers find old positions more stimulating
Anterior circulation of the brain is supplied mostly by what
ICA
Posterior circulation of the brain is supplied mostly by what
Vertebral arteries branching off the subclavian
What do the vertebral arteries merge into
Basilar artery - joins the posterior circle of Willis
What is amaurosis fugax
TIA of the eye, its like a curtain coming down but is painless
What is the management
Aspirin, clopidogrel (anti-platelets)
Steroid if it is GCA
Trace the visual pathway
Photoreceptors to bipolar cells to ganglion cells to optic nerve to LGN to visual cortex
What can cause unilateral field loss
Optic nerve compression
Homonymous hemianopia
Right cerebrovascular event
macular sparing homonymous hemianopia
Stroke - This happens as the macula received dual blood supply
