Sensory Nerves *The Nasociliary nerve--> longposterior ciliary nerve(globe) , senosry fibers through ciliary ganglion, and nasal mucosa, skin at tip of nose. (Hutchinson’s Sign)
Ciliary Ganglion• 1.5 mm Lateral to the apical optic nerve.• Sensory branches from nasociliary nerve.(pass through only).• Parsympathetic fibers from (ciliary body and sphincter pupillae). (synapse)• Sympathetic fibers from ICA for iris dilator muscle. (pass through only)
Infra-orbital Nerve• Main continuation of V2.• Infra-orbital groove (surgical land mark)• Provides sensation of lower lid,cheek, medial upper lip.• * Zygomatic branch--> zygomaticomaxillary, and zygomaticfacial to innervate zygoma and lateral orbit.
Pterygopalatine Ganglion (PG)* Parasympatheticganglion of the head andneck.* Greater Palatine nv.->Palatine nerve-> PG->Zygomaticotemporal->Lacrimal nv.
Motor Nerves Oculomotor Oculomotor• Exits brain stem between post- communicating and superior cerebellar artery.• Lateral wall of cavernous sinus and divides into superior and inferior division.• Through SOF through annulus of Zinn.
Arterial Supply• The internal carotid artery give off the ophthalmic artery.
Ophthalmic Artery• Only ICA branch that enters the orbit.• Aastomoses with ECA branches.• Enters orbit inferolateral to optic nerve.• At orbital Apex Branches: to retina (CRA) and choroid (PCA).• Short PCA : 15-20 from LPCA pierce sclera and supply ONH and choroid.
Branches of External Carotid Artery * Orbital circulation has highdegree of collateralization with ECA . * Supra-orbital and Supratrochlear<--> Superficial temporal Art.* Dorsonasal <--> Angular Art.*Ant and Post. Ethmoidal <--> Sphenopalatine * Lacrimal Art. <--> Middle Meningeal Art.
Venous Outflow• Valveless veins which drain posteriorly.• The Superior orbital vein (SOV) is a confluence of angular, naso-frontal, and Supra-orbital vein.• Directed from medial to lateral.• Starts near trochlea, medial to SR-- >beneath SR--> Lateral to SR--> SOF.
Inferior Orbital Vein• Drains posteriorly (anastomoses with Supra-orbital vein)--> Inferior orbital fissure--> into Pterygoid venous plexus and Inferior orbital fissure.
Orbital Vasculature• Ophthalmic artery (1st Branch of ICA).• Primary blood supply (small contribution from ECA: maxillary and middle meningeal arteries).• Branches variable.• Ophthalmic artery enters the optic canal.
Branches of Ophthalmic Artery• Central retinal artery (Retina).• Long posterior ciliary arteries (Choroid) ; 1)Short Posterior Ciliary Arteries (15-20) supply choroid and optic nerve head. 2) Long Post Cililary (2) for Iris and Ciliary body.• Lacrimal artery. (gland) recurrent meningeal art. anastomosis• Anterior & Posterior ethmoidal.• Muscular Branches (divides into 2 long anterior ciliary arteries except LR has 1 only).--> anastom with long post. ciliary arteries (supply anterior segment).
Venous Drainage of Orbit• Valveless superior and inferior ophthalmic veins.• Confluence of the angular, supraorbital, and supratrochlear veins form superior ophthalmic vein.• Inferior ophth vein receives tribuatries from muscular, vortex, and medial and lateral collateral veins.• IOV communicates with pterygoid plexus via IOF.