Flashcards in Orbit Deck (16)
Bones contributing to the walls of the Orbit:
Superior wall – orbital plate of frontal bone
Lateral wall – greater wing of sphenoid and the orbital plate of zygoma
Inferior wall – orbital plate of maxilla
Medial Wall – frontal process of maxilla, lacrimal bone, orbital plate of ethmoid and the less wing of sphenoid
Intrinsic Muscles of the Eye (name and innervation):
Dilator pupillae- sympathetic
Sphincter pupillae- parasympathetic
Ciliary muscle - parasympathetic
Extrinsic Muscles of the Eye (name, function and innervation):
4 recti (superior, inferior, medial and lateral) - all innervated by CN 3 apart rom lateral innervated by abducens
2 oblique (inferior CN3, superior CN4)
Eyelid muscles - LPS and orbicularis oculi
Ophthalmic branch of CN V –
Branches (name the branch and identify the type of autonomic nerves hitchhiking):
Lacrimal - parasympathetic from the pterygopalatine ganglion
Frontal - supratrochlear and supraorbital
Nasociliary nerve - ciliary branches (sympathetic and the parasympathetic branches), Ethmoidal, infratrochlear
Oculomotor Nerve –
This efferent nerve splits into superior and inferior branches, identify the muscles innervated by both branches and describe the autonomic hitchhikers which traverse along them.
• Superior branch:
Levator palpebrae superioris
o Autonomic hitchhiker:
sympathetic fiber (synapse at superior cervical ganglion C2 and travel to the carotid plexus and ophthalmic artery) innervates Dilator pupillae, blood vessels and the superior tarsal muscles
• Inferior branch:
o Autonomic hitchhikers:
Parasympathetic - sphincter pupillae and the ciliary body
Pathway of the Trochlear and Abducent Nerves –
These nerves travel through the cavernous sinus (CN VI travels close to the ICA) and exit the cranium via the superior orbital fissure. CN IV innervates the superior oblique, CN VI innervates the lateral rectus.
Arterial supply to the orbit is via the ophthalmic artery which then branches into:
(Some Men Cut Soldiers Like Cheese)
2. muscular branches
6. central artery of the retina
Venous drainage is via 2 main veins
Venous drainage is via 2 main veins, the superior and inferior ophthalmic veins.
Superior ophthalmic vein - through the superior orbital fissure and into the cavernous sinus
-> all nerves go through here so infection can be very severe
inferior ophthalmic vein - through the inferior orbital fissure and joins the pterygoid plexus
What is the consensual response?
retinal gnaglion cells
pre tectal nucleus
edinger westphal nucleus
edinger westphal nucleus
both sphincter pupillae
What travels in the superior orbital fissure?
What travels in the inferior orbital fissure?
infraorbital vessels - inferior ophthalmic vein
What travels through the optic canal?
the superior ophthalmic artery
What is the levator palpabri superioris innervated by?
What happens if the oculomotor nerve has a lesion?
1. eye down and out
2. Loss of innervation to the levator palpibrae superioris - ptosis
3. loss of parasympathetic function - mydriasis
What is horner syndrome
lesion to upper sympathetic trunk
Myosis (constricted pupil)
anhydrosis (reduced sweating)