Gross Anatomy of the Orbit

Strong, fibrous bands that help control eye movements by attaching to the tendons of the rectus muscles and the orbital wall.

A thin, fibrous membrane that surrounds the eyeball and fuses with the tendons of the extraocular muscles.

A firm, thickened area of Tenon's capsule where the tendons of the rectus muscles attach.

A thick band of fascia that lies above the levator palpebrae superioris muscle, helping to control eyelid elevation.

A transverse band of fascia that separates the levator palpebrae superioris from the superior rectus muscle.

A suspensory band of fascia that passes beneath the inferior rectus muscle and helps support the eye.

A continuation of the suspensory ligament of Lockwood that connects to the tarsal plate of the lower eyelid.

Smooth muscle found in the orbit that plays a role in regulating eye position.

The muscles responsible for eye movement, including the superior, inferior, medial and lateral rectus muscles, become thicker and wider at their middles.

The superior oblique muscle originates narrow but widens to a maximum of about 5mm.

Hyaline cartilage ring in the frontal bone, located at the upper medial angle of the orbit.

The superior oblique muscle passes through the trochlea, changing direction by about 54 degrees.

The superior oblique muscle inserts obliquely to the upper lateral posterior quadrant of the sclera.

The superior oblique muscle's length from the origin to the trochlea is 32mm, and from the trochlea to the insertion is 20mm.

The trochlear nerve crosses above the levator and enters the lateral edge of the superior oblique muscle.

The tendons of the rectus muscles insert in the anterior half of the globe 3-8mm from the limbus.

Nerves responsible for pupillary constriction and accommodation. They originate from the Edinger-Westphal nucleus in the midbrain, synapse in the ciliary ganglion, and then travel to the ciliary muscle and sphincter pupillae.

A ganglion located in the orbit that receives preganglionic parasympathetic fibers from the Edinger-Westphal nucleus via the oculomotor nerve.

A ganglion located in the pterygopalatine fossa that receives preganglionic parasympathetic fibers from the facial nerve.

The central artery that supplies blood to the retina. It enters the eye through the optic nerve and branches out to nourish the retina.

Arteries that enter the eye alongside the motor nerves and supply the extraocular muscles and bulbar conjunctiva.

Arteries that penetrate the sclera and supply the choroid, the vascular layer of the eye.

Arteries that enter the eye on either side of the globe and supply the iris, the colored part of the eye.

The main artery that supplies blood to the eyelids.

The ophthalmic artery has connections with branches of the external carotid artery, meaning it's not a "dead end" artery.

An anastomosis is a natural connection between two blood vessels, allowing blood flow even if one vessel is blocked.

The recurrent meningeal artery, sometimes called the accessory ophthalmic artery, connects the lacrimal and middle meningeal arteries, providing a vital link in the orbital blood supply.

While lymphatics are present in the conjunctiva and eyelids, they are not found in the eye itself.

The rami orbitales, branches of the ophthalmic artery, are important for supplying blood to the eye, lacrimal gland, and orbital blood vessels.

Rami oculares, fine branches of the rami orbitales, enter the eye posteriorly, supplying the choroid and contributing to dilating the pupil.

Rami lacrimales are a direct path for parasympathetic innervation to the lacrimal gland, controlling tear production.

Rami vasculares and oculares have a vasodilatory function, meaning they widen blood vessels.

The two main veins of the orbit are the superior and inferior orbital veins. These veins drain blood from the eye, with the vortex veins contributing to the ophthalmic veins.

Blood flow in orbital veins is affected by posture due to the lack of valves. This means blood can flow in different directions based on body position.

The ophthalmic veins join the cavernous sinus, connecting the orbital venous system to the intracranial system.

Orbital veins have connections to facial veins, deep facial veins, and the cavernous sinus. This interconnectedness can lead to potential spread of infection.

The vortex veins drain blood from the eye and connect to the nearest ophthalmic vein.

The central retinal vein drains blood from the retina and joins the ophthalmic veins.

The anastomoses between the internal and external carotid arteries contribute to the blood supply of the orbit, especially when one artery is blocked.

Collaterals help ensure blood supply to the orbit even if there is a blockage in one of the main arteries.

A type of orbital fracture that involves the floor of the orbit without affecting the rim. It often leads to impaired vertical eye movement (diplopia), and sinking of the eye (enophthalmos).

A theory that suggests blunt trauma to the eye causes a rapid increase in pressure within the orbit, which then leads to a fracture in the orbital walls.

A theory that proposes that a blow to the rim of the orbit transmits force to the orbital walls, leading to a fracture.

The most common location for "blow-out" fractures, because it lacks reinforcement and overlies the maxillary sinus.

A nerve that often gets damaged in orbital floor fractures, leading to sensory disturbances in the mid-face.

A common sign of orbital floor fracture, caused by damage to the infra-orbital nerve.

A condition where the eye appears sunken in the socket, often resulting from an orbital floor fracture.

Double vision, often a symptom of an orbital floor fracture, caused by impaired vertical eye movement.