Eye Gross Anatomy Laboratory

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SUBJECT: NEUROANATOMY TOPIC: EYE GROSS ANATOMY LABORATORY LECTURER: DR. JOSE ANTONIO AMISTAD DATE: FEBRUARY 2011

-----Review of Ear Gross Anatomy--------------------------------------------SELHURSTS EAR (a.k.a. Cup-handle ear) the only part of the external ear that is enlarged is the helix. ZAHEERS EAR absence of antitragus; usual manifestation is earphones falling off the ear (as opposed to snug insertion). STAHLS BAR spiked ear (or a.k.a. Spocks ear); presence of a middle crux of the antihelix (in between the superior crux and the inferior crux). CRYPTOTIA fusion of the whole ear lobe (not the lobule) to the mastoid area. Grading of MICROTIA (small or partially developed ears): Grade 1: Near MINIATURE of the normal ear (no definite surface anatomy regarding the size of the normal ear according to Google, the average size of the ear is from the end of the lateral part of the eye brow until the angle of the mouth which is still in need of citation!) y Everything is normal about the ear, its just that its on a smaller scale.

ORA SERRATA - anterior end of the retina (which is the start of the ciliary bodies) that marks the transition from the retina to sclera. FIBERS OF ZINN - fibers that hold the lens.*Ciliary muscles and the fibers of zinn are responsible for accommodation.

WIEGER BAND - Dorsal part of the lens. HYALOID ARTERY During the embryonic period, there is an arterial supply to the lens by the HYALOID ARTERY. But during second trimester, this artery will undergo fibrous degeneration. If otherwise, the lens will have a persistent blood supply that would cause accumulation of CALCIUM IONS that would lead to OPACITY.*The plasma is composed of different microamounts and calcium is one of them. electrolytes in

GERMAN MEASLES/RUBELLA VIRUS Maternal infection of german measles or the rubella virus would lead to persistence of the hyaloid artery. This would lead to opacity (2o to accumulation of calcium in the lens) and produce RUBELLA CATARACT.*Four types of Congenital Cataract: y Lamellar like a ring y Zonular part of the lens is opacified. y Structural there is a Y-shaped non-opacified area. y Global whole lens undergoes opacification.

Grade 2: HEMI-EAR (Abnormal contour in the parts of the ear) y i.e. antihelix is somewhat peperpendicular; worst case scenario: clefting of the helix

Grade 3: PEANUT-SHAPED ear (vestigial remnant, very stenotic [narrowed] ear canal) Grade 4: ABSENCE of the ear lobe or remnants of the anlagen of the ear lobe - auricular hillocks INTERTRAGICAL NOTCH space between the tragus and antitragus. AURIS DEXTRA (AD) dealing with right ear. AURIS SINISTRA (AS) dealing with left ear. AURIS UTERQUE (AU) dealing with both ears. ------End of Review---------------------------------------------------------------------EYE GROSS ANATOMY *CRYPTOPTHALMOS abnormal congenital fusion of the two eyelids. OCULI DEXTRA (OD) dealing with the right eye. OCULI SINISTRA (OS) dealing with the left eye. OCULI UTERQUE (OU) dealing with both eyes. INTRINSIC PARTS OF THE EYE GLOBE(Please refer to Figure 1 for this particular discussion)

CANAL OF CLOQUET (HYALOID CANAL) The remnant canal during 2nd trimester age of gestation which was embryologically occupied by the hyaloid artery. *Cloquets nodes femoral nodes. (Dont be confused!) MITTENDORFS DOT - remnant of the posterior attachment of the hyaloid artery. ------------------------------------------------- ----------------------------------------------Normal blood pressure 120/80 10; depending on the age and BMI.Vitamin needed for the functional integrity of the eye globe? For vitreous humor and rods and cones, you need vitamin A. For the aqueous humor and the four avascular structures (anterior lens, posterior cornea, anterior vitreous, trabecular network), you need the antioxidant vitamin C.

------------------------------------------------- ----------------------------------------------VITREOUS HUMOR Composed of 98-99% of water. It is 4x more viscous than water. It is produced from continuous reprocessing of hyaluronic acid and collagen type II (parts of the microfilaments). Without these you will have an unstable globe. The vitreous humor you have today is the same one youve had since your 25th day age of gestation. It is never replenished. HYALOCYTES OF BALAZS Macrophage-acting cells within the vitreous humor that are responsible for: (1) maintaining the reprocessing of hyaluronic acid, and (2) capturing of any foreign bodies. Page 1

SCLERA & RETINA - layers that occupy 7/10 of the eye globe.

NEUROANATOMY: EYE GROSS ANATOMY LABORATORY DISCUSSION

*RECALL: Macrophages in: Liver :: Kupffer cells Connective Tissue :: Histiocytes Skin :: Langerhans cells Brain :: Microglia Blood Cell macrophage :: Monocytes Lungs :: Pulmonary Alveolar Macrophages

OPHTHALMIC ARTERY Will become: 2 LONG CHOROIDAL arteries (which give supply to to the anterior-most choroid); and approximately 20 SHORT CHOROIDAL arteries (that give supply to the choroid).

AQUEOUS HUMOR Contains vitamin C and is also composed of immunoglobulins, amino acids, and microamounts of proteins. How does the aqueous humor drain to the right atrium? We answer this question by explaining the arterial supply, production and flow of aqueous humor, and venous drainage of the eye. ARTERIAL SUPPLY (split into pathways, Josh & Diagrams) BLOOD CIRCUITRY FROM THE HEART (Refer to Figure 2) Heart Right Atrium Right Ventricle Pulmonary Artery Lungs (for oxygenation) Pulmonary Veins (4 of them) Left Atrium Left Ventricle Ascending Aorta Arch of the Aorta Thoracic Aorta Three main branches of the Arch of the Aorta: 1. Brachiocephalic Trunk splits into the Left Common Carotid and Left Subclavian Arteries 2. Right Subclavian Artery 3. Right Common Carotid Artery Branches of the Subclavian (Mnemonic: VIT C&D) Vertebral, Inferior Thyroid, Thyrocervical, Costocervical, Dorsal Scapular Right Subclavian Left Subclavian

ANTERIOR CHOROIDAL ARTERY It is the branch of MCA that will assist the two long choroidal arteries. This branch will become the ANTERIOR CILIARY ARTERIES that would supply the ciliary bodies. PRODUCTION, FLOW, AND DRAINAGE OF AQUEOUS HUMOR CILIARY BODY The ciliary body will convert the plasma (from the blood coming from the anterior ciliary artery) into a fluid called aqueous humor. This aqueous humor is secreted into the CLEFT OF THE POSTERIOR CHAMBER (area behind the iris) and flows out of the pupil to reach the anterior chamber. From there it is drained by the trabecular meshwork and further drained by a system of canals (canal of Schlemm).*Absence of the cleft of the posterior chamber may lead to decreased production of aqueous humor.

TRABECULAR MESHWORK It is a sponge-like network of tissue located on the inferior side of limbus (or posterior half-moon junction of limbus). CANAL OF SCHLEMM It is the main gate towards the circulatory system which means they are NOT ARTERIES OR VEINS. Summary of Flow: Ciliary Body

Vertebral

Vertebral Cleft of Posterior Chamber Basilar Artery Pupil Posterior Cerebral Artery Posterior Communicating Artery(Refer to Figure 3)

Anterior Chamber Trabecular Meshwork Canal Of Schlemm

Branches of the Common Carotid 1. External Carotid (Mnemonic: SALFOPSM or Some Aggressive Lovers Find Odd Positions More Stimulating HAHA!) - Superior Thyroid, Ascending Pharyngeal, Lingual, Facial, Occipital, Posterior Auricular, Maxillary, Superficial Temporal 2. Internal Carotid does not branch in the neck region. It ascends to meet with the posterior communicating artery. Before the Internal Carotid Artery (ICA) and the Posterior Communicating meet, the ICA will give off a branch called the OPHTHALMIC ARTERY. After they meet, the ICA is now called the MIDDLE CEREBRAL ARTERY and gives of a branch, the ANTERIOR CHOROIDAL ARTERY.

Ciliary Body

NEUROANATOMY: EYE GROSS ANATOMY LABORATORY DISCUSSION

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VENOUS DRAINAGE From the Canal of Schlemm, the aqueous humor will drain into the AQUEOUS VEINS and then into the EPISCLERAL VEINS. Some of the fluid coming from the Schlemm will proceed first to the INTRASCLERAL PLEXUS but will eventually drain into the episcleral vein.*If there is thrombosis in the aqueous vein, the intrascleral plexus will serve as a contingent pathway for the fluid.

*DRAINAGE OF VITREOUS HUMOR NONE! The vitreous humor is not drained because it is never replenished and it is equipped with its own macrophages. GLAUCOMA There will be a continuous production of aqueous humor but there will be no turnover rate leading to increased intraocular pressure. There are two types: OPEN ANGLE GLAUCOMA

The episcleral vein will then drain into the ANTERIOR CILIARY VEIN. This anterior ciliary vein will anastomose with 4-6 VORTICOSE (or vortex) veins. These vorticose veins are the first veins outside of the eye globe.Superotemporal Vorticose

Inferotemporal Vorticose

The SUPEROTEMPORAL VORTICOSE vein will drain into the SUPERIOR OPHTHALMIC vein. The superior ophthalmic vein will drain its content into the ANGULAR VEIN. Once the angular vein passes on the lower border of the inferior orbit, it will change its name to the FACIAL VEIN. Then from there, it drains to the EXTERNAL JUGULAR vein Subclavian Vein merges with the Internal Jugular vein to from the Brachiocephalic vein. Two Brachiocephalic veins (right and left) join to from the Superior Vena Cava and down to the Right Atrium. The INFEROTEMPORAL VORTICOSE vein drains into INFERIOR OPHTHALMIC vein. From there it drains to the PTERYGOID PLEXUS found at the cranial base and is the largest network of veins. The pterygoid plexus will become the MAXILLARY VEIN and will anastomose with the RETROMANDIBULAR VEIN. The retromandibular vein will have two tributaries, the ANTERIOR and POSTERIOR retromandibular veins.