Anatomy (Eye)

Which muscles are anterior to the equator of the eye?

All recti muscles.

What is corneal limbus?

Angle formed between the intersection of curvatures of cornea and sclera at the corneoscleral junction.

What constitues the posterior chamber of the eye?

Anteriorly: iris Posteriorly: lens and ciliary body

Where does the optic part of retina terminate anteriorly?

At the ora serrata (junction between retina and ciliary body), posterior border of the ciliary body

What is cornea?

Avascular, receives nourishment from capillary bed on its periphery and from fluids (lacrimal externally and aqueous humer interiorly) Lacrimal fluid provides the oxygen. Highly sensitive to touch, innervated by opthalmic nerve CN V_1

How many layers does the eyeball have and which?

Fibrous layer (contains sclera and cornea) Vascular layer (choroid, ciliary body and iris) Inner layer (retina - optic and nonvisual part)

Test of eye?

Follow finger medially (testing MR and oculomotor nerve) then inferiorly and superiorly to isolate SO and IO (trochlear nerve and inferior divsion of oculomotor nerve)

What are the terminal branches of opthalmic nerve within cavernous sinus?

Frontal, nasociliary and lacrimal nerve which all pass through superior orbital fissure.

Where is ciliary ganglion located?

Group of postsynaptic parasympathetic nerve cellbodies located between optic nerve and lateral rectus

What does vortex drain into?

Inferior opthalmic vein

What is opthalmic artery a branch of?

Internal carotid artery

What is the ciliary body?

Located posterior to the corneoscleral junction and it connects the choroid with the circumference of the iris. Smooth muscles of ciliary body controls the thickness of the lens. Folds within the ciliary body, ciliary processes secrete the aqueous humor, fills the anterior chamber of the eyeball.

What are the branches of nasociliary nerve?

Long ciliary nerves, anterior and posterior ethmoidal nerves and continues as the infratrochelar nerve

Where is aqueous humor produced?

Produced in the posterior chamber and it supplies the cornea and lens.

What is the pigmented layer?

Single layer of cells that reinforces the light-absorbing property of choroid by reducing the scattering of the light into the eyeball.

What controlls the size of pupil?

Sphincter pupillae and dilator pupillae muscles.

Which muscles are posterior to the equator of the eye?

Superior and inferior oblique muscles.

What pierces the fascial sheath?

Tendon of extraoccular muscles reflected onto the sheath as tubular muscle sheaths.

Venous drainge of the eye?

Through superior and inferior opthalmic veins, passes through superior orbital fissure and enter cavernous sinus.

How is aqueous humor removed?

Through the limbal plexus it drains into verticose and anterior ciliary veins. This is important that it goes correct for the intraoccular pressure.

What does tendon of superior oblique muscle traverse?

Trochlea

What is the capsule of the lens anchored by?

Zonular ligament which collectively form the suspensory ligament of the lens, the ciliary muscles of the ciliary body changes the shape of the lens. Ciliary muscles of ciliary body changes shape of the lens through the zonular ligaments collectively forming the suspensory ligament of the lens.

What is the non-visual retina?

Continuation of the non-pigmented layer, which extends over ciliary body as ciliary part and posterior surface of iris as the iridial part.

How does the light wave pass?

Cornea which is the primary border of the light to aqueous humer, to the lens and lastly to vitreous humor.

What does fibrous layer of eyeball provide?

Shape and resistance

What is the common function of retrobulbar fat and check ligaments?

They resist the posterior pull produced by recuts muscles. Thus starvation cause a retraction of the eyeball (inopthalmos)

What are the sphincter pupillae muscles?

They are circulary arranged and decreases the diameter of the pupil by innervation of sympathetic fibers.

What are the dilator pupillae muscles?

They increase the diameter of the pupil by innervation of parasympathetic fibers.

What is suspensory ligament of eyeball?

Blending of check ligamnets with fascia of inferior rectus and inferior oblique forming a hammock.

Central artery of retina?

Branch of opthalmic artery, it is inferior to optic nerve and pierces the sheath of optic nerve.

What supplies the retina?

Central artery of retina (branch of opthalmic artery) and choricocapillaris.

What is external aspect of retina supplied by?

Choricocapillaris

What constitutes the vascular layer of eye ball?

Choroid, ciliary body and iris

What does retina of fundus include?

Circular area known as the optic disc where pure sensory fibers of optic nerve and vessels enter the eye ball. The optic disc is known as the blind-spot!

What is scleral venous sinus?

Enricles anterior chamber of eyeball and is the vein responsible for the return of aqueos humor to the blood circulation.

Check ligaments?

Expansions from medial and lateral rectus sheath and are known as medial and lateral ligament, they are attached to lacrimal bone and zygomatic bone respectively. They limit abduction and adduction

What is the fascial sheath?

Extending form conjuctival fornices to the optic nerve.

What is intra-orbital artery a branch of?

External carotid artery

What is the function of the vitreous humor?

It is enclosed in the vitreous body and it holds the retina in place and supports the lens.

What is this iris?

It lies anterior to the lens, has a central aperture known as the pupil

What are the characteristics of the levator palpebrae superioris?

It widens along its insertion and its deep lamina includes smooth muscle fibers of the superior tarsal muscle, producing additional widening of the palpebral fissure. Interruption of the sympathetic fibers (Horners syndrome) results in ptosis (dropping of upper eye lid)

Which are the yoke muscles if you gaze to the irght?

Left medial and right lateral act as yokes.

What is neural layer?

Light receptive layer.

What is lateral to the optic disc?

Macula lutea (yellow spot), contains special photoreceptor responsible for acuicity of vision. Center of macula lutea is a depression, fovea centralis, which is the area MOST acute vision.

Which muscle sheath is fused?

Muscle sheath of superior rectus and superior oblique are fused thus when gaze is superior the eyelid is even more elevated out of vision.

What layers does the optic part have?

Neural layer and the pigmented layer.

What is sclera?

Part of fibrous layer, provides attachment for extraoccular and intrinsic muscles of the eye. Anterior part of sclera is visible as the bulbar conjuctiva (white eye)

Optic nerve pathway?

Purely sensory fibers (CN II) and they are developed as paired anterior extensions of forebrain and thus are CNS fiber tracts formed of second-order neurons. It beings at lamina cribrosa of the sclera, pierces the sclera and becomes in this case myleinated just posterior to the optic disc. Are surronded by extensions of cranial meninges and subarachoniad space is filled by CSF.

What is the most inner layer of the eye ball?

Retina, it has a optic part and a non-visual part

What forms the central vein of retina?

Retinal veins

What is ocular fundus?

The area where light is focused.

What is choroid?

The inner vascular layer interior to the sclera of external fibrous coat of the eye. It lines most of sclera. Responsible for the red eye during photography with flash Choroid is continous with ciliary body anteriorly, in fact it is a triangular expansion of the choroid.

What constitutes the anterior chamber of the eye?

The space between cornea anteriorly and pupil posteriorly.