Orbit and Eye Lecture Notes

Comprehesive vocabulary flashcards covering the bony anatomy, eyelid structures, lacrimal apparatus, globe layers, and extraocular muscle functions and testing.

Optic canal

A hole in the lesser wing of the sphenoid bone that transmits the Ophthalmic artery and $CN\,II$ (Optic nerve).

Superior orbital fissure

The gap between the lesser wing and greater wing of the sphenoid bone transmitting $CN\,III$, $CN\,IV$, $CN\,V_1$, $CN\,VI$, and the superior ophthalmic vein.

Inferior orbital fissure

The gap between the greater wing of the sphenoid bone and the maxilla that transmits infraorbital vessels and the infraorbital nerve.

Orbital fat

Substance that fills all spaces within the orbit not occupied by the eyeball, extraocular muscles, branches of cranial nerves, and blood vessels.

Orbital septum

A membranous sheet attached to the orbital rim that forms part of the fibrous layer of the eyelid.

Levator palpebrae superioris muscle

The muscle responsible for elevating the upper eyelid, innervated by the oculomotor nerve.

Superior tarsal muscle

A smooth muscle innervated by the sympathetic nervous system that assists the levator palpebrae superioris in elevating the eyelid.

Tarsal glands

Glands embedded within the tarsal plates that secrete an oily substance onto the margin of the eyelid.

Conjunctival sac

The space between the palpebral conjunctiva (lining the inner eyelid) and the bulbar conjunctiva (lining the sclera).

Nasolacrimal duct

The structure extending inferiorly from the lacrimal sac that enters into the inferior meatus of the nasal cavity.

Ciliary muscle

Smooth muscle innervated by the parasympathetic nervous system that contracts to change the shape of the lens for accommodation.

Aqueous humor

Fluid in the aqueous compartment (anterior and posterior chambers) that drains into the scleral venous sinuses.

Refractive media

Structures including the cornea, aqueous humor, lens, and vitreous humor that help focus light rays onto the retina.

Pupillary sphincter muscle

Smooth muscle that contracts under parasympathetic stimulation to constrict the pupil.

Pupillary dilator muscle

Smooth muscle that contracts under sympathetic stimulation to dilate the pupil.

Annular tendon

A ring of fibrous tissue surrounding the optic canal at the apex of the orbit, serving as the common origin of the four rectus muscles.

Superior oblique muscle

Extraocular muscle that depresses and abducts the pupil; innervated by the trochlear nerve ($CN\,IV$).

Inferior oblique muscle

Extraocular muscle that elevates and abducts the pupil; innervated by the oculomotor nerve ($CN\,III$).

Superior rectus muscle testing

To isolate this muscle for testing, the patient must abduct the pupil and then elevate it.

Superior oblique muscle testing

To isolate this muscle for testing, the patient must adduct the pupil and then depress it.

Ciliary ganglion

A parasympathetic ganglion located between the optic nerve and the lateral rectus muscle containing postganglionic cell bodies.

Superior ophthalmic vein

A valve-less vessel that drains posteriorly into the cavernous sinus.