The ophthalmic artery, the first major branch of the internal carotid artery, enters the orbit via the superior orbital fissure, whereupon it gives off the central artery of the retina and branches to the extraocular muscles. It also ascends on the lateral surface of the optic nerve and gives the lacrimal artery. The lacrimal artery has a recurrent meningeal branch that anastomoses with the anterior branch … Continue reading Eye blood vessels

There are three groups of the muscles of the eye: Intraocular: ciliary muscle (changes lens shape) and pupillary dilators/constrictors Extraocular muscles of eye movement: 4 recti and 2 oblique muscles Extraocular elevator of the upper eyelid: levator palpebrae superioris The superior division of the oculomotor nerve (CN III) innervates levator palpebrae superioris and the superior and medial recti while the inferior division innervates the inferior … Continue reading Eye muscles

The orbit is a bony socket of the facial skeleton formed around the optic nerve and eyeball. Each orbit is cone-shaped, with the apex pointing posteromedially so that the medial walls of the two orbits are almost parallel while the lateral walls are virtually perpendicular. Posteriorly, the orbit communicates with the cranial cavity via the superior orbital fissure and with the pterygopalatine fossa via the … Continue reading Bony orbit

The cranial nerves II, III, IV Va and VI contribute to functions of the eye. Besides the optic nerve, the rest travel through the cavernous sinus and superior orbital fissure. CN II, IV and VI which provide motor control of the eye are often tested by having a patient tracing the letter “H” with their gaze. LR6SO4 (CN VI innervates lateral rectus, CN IV innervates … Continue reading Eye nerves: CN II, III, IV, Va & VI