Orbital Cavity and Contents - Review Flashcards

Flashcards covering the anatomy of the orbital cavity, its boundaries, contents, ligaments, lacrimal apparatus, eyelids, and extraocular muscles.

What are the four walls of the bony orbit?

Roof, floor, medial wall, and lateral wall.

Which bones form the medial wall of the orbit?

Frontal process of maxilla, lacrimal bone, and orbital plate of ethmoid.

What forms the roof of the orbit?

Orbital plate of the frontal bone and the lesser wing of the sphenoid.

What forms the floor of the orbit?

Orbital surface of the maxilla and the maxillary process of the zygomatic bone.

Which bones form the lateral wall of the orbit?

Frontal process of the zygomatic bone and greater wing of the sphenoid.

What is the optic canal and what does it transmit?

A passage in the lesser wing of the sphenoid; transmits the optic nerve and the ophthalmic artery.

Which nerves and vessels pass through the superior orbital fissure?

Lacrimal nerve, frontal nerve, trochlear nerve, oculomotor nerve (superior and inferior divisions), abducent nerve, nasociliary nerve, and the superior ophthalmic vein.

What passes through the optic canal?

Optic nerve and ophthalmic artery.

What are the principal contents of the orbit?

Eyeball, lacrimal apparatus, seven extraocular muscles, cranial nerves (optic and ophthalmic plus motor nerves), autonomic nerves, ophthalmic vessels, orbital ligaments, fascia, and fat.

What is Lockwood's ligament?

Suspensory hammock of the eyeball; anchors the inferior conjunctival fornix; part of Tenon’s capsule.

What are the main parts of the lacrimal apparatus and where are they located?

Lacrimal gland (main part in lacrimal fossa of the roof; palpebral part in the upper eyelid), conjunctival sac, lacrimal sac and nasolacrimal duct, and lacrimal puncta/canaliculi.

What nerve supplies parasympathetic innervation to the lacrimal gland?

Greater petrosal branch of the facial nerve (via the pterygopalatine ganglion).

Where is the lacrimal gland located and what are its parts?

Main part in the lacrimal fossa of the orbital roof; palpebral part embedded in the lateral part of the upper eyelid.

Where is the lacrimal sac located?

In the lacrimal groove between the anterior and posterior lacrimal crests.

Where does the nasolacrimal duct drain?

Into the inferior meatus of the nose.

What are the layers of the eyelid from outside to inside?

Skin, superficial fascia, tarsus, conjunctiva.

What is the palpebral fissure?

The fissure between the two eyelids.

Which arteries supply the upper and lower eyelids?

Medial palpebral arteries (from the ophthalmic artery) and lateral palpebral arteries (from the lacrimal artery).

Which nerves supply the eyelids (sensory innervation to upper and lower lids)?

Upper eyelid: branches of the ophthalmic nerve (V1); lower eyelid: branches of the maxillary nerve (V2).

Name the four rectus muscles of the eye.

Superior rectus, inferior rectus, medial rectus, and lateral rectus.

Name the two oblique muscles of the eye.

Superior oblique and inferior oblique.

From where do the rectus muscles originate?

From the common tendinous ring (annulus of Zinn) at the apex of the orbit.

Where do the rectus muscles insert on the eyeball?

Into the sclera about 5.5–7.5 mm behind the corneoscleral junction.

Which nerve supplies the superior oblique muscle?

Trochlear nerve (CN IV).

Which nerve supplies the lateral rectus muscle?

Abducent nerve (CN VI).

Which nerve supplies the remaining extraocular muscles (besides LR and SO)?

Oculomotor nerve (CN III) provides motor supply to the other four recti and the inferior oblique.

What is the action of the superior rectus muscle?

Elevates the eye, adducts it, and rotates it medially.

What is the action of the inferior rectus muscle?

Depresses the eye, adducts it, and rotates it medially.

What is the action of the medial rectus muscle?

Adducts the eye (moves toward the nose).

What is the action of the lateral rectus muscle?

Abducts the eye (moves away from the nose).

What is the action of the superior oblique muscle?

Depresses, adducts, and rotates the eye medially (intorsion).

What is the action of the inferior oblique muscle?

Elevates, abducts, and rotates the eye laterally (extorsion).

What is the role of the annulus of Zinn?

A fibrous ring around the optic nerve from which the four rectus muscles originate.