C: Smooth muscle that is innervated by the sympathetic nervous system. Mueller’s muscle provides an extra 2-3mm of lift to the eyelids. Loss of innervation to this muscle will lead to a mild ptosis (i.e. Horners)

B: Frontalis muscle is responsible for the look of surprise. The frontalis is activated in cases of ptosis and dermatochalasis to assist with raising eyelids. The corrugator creates the look of concentration. Procerus, think rhinoceros.

D: Seven – Frontal, Ethmoid, Sphenoid, Lacrimal, Maxilla, Palatine, and Zygomatic

All but C: Recall the mnemonic “the nose SMELs” for medial wall of orbit.

B,E: The Greater wing and the Zygomatic bones comprise the lateral wall (Great-Z)

B: Microglial cells phagocytose waste and cells in the retina. Alveolar cells are found in lungs. WBCs are found in the bloodstream. Kupffer are phagocytic cells in the liver.

B: Tenon’s capsule – To remember, consider C.C. TESLA From anterior to posterior: C. epithelium, C. stroma, Tenon’s capsule, Episclera, Scleral proper, Lamina fusca, and Anterior choroid

A: Vortex veins are responsible for draining most of the blood from the eye. There are often 4-6 vortex veins in each eye noted at mid-periphery.

D: The Scleral Spur is the origin of the longitudinal muscle fibers. The muscle inserts into the anterior choroid.

B: CNII, the oculomotor nerve, is responsible for innervating the levator muscle. CN VII, the facial nerve, closes the eye. CN I is the olfactory nerve. CN II is the optic nerve, CN IV is the trochlear nerve.

D: CN IV, the trochlear nerve as it is not only the thinnest nerve, it also has the longest course of all cranial nerves as it leaves the brainstem dorsally.

C: Innervates the SUPERIOR oblique; all other statements are correct.

C: The sclera is thinnest at recti muscle insertions with a thickness of about 0.3mm. The thickest is the posterior pole at about 1mm.

D: Common Tendinous Ring is the site of origin of all four recti muscles. Circle of Zinn is composed of short posterior ciliary arteries. The Spiral of Tillaux involves the insertion of the recti muscles.

B. Recall that torsion is a primary function of obliques; OBliques ABduct (or O’s to the nose); and obliques have opposite roles in supraduction.

B: Inferior Oblique is the only muscle to originate from maxillary bone.

E. The Superior and Inferior ophthalmic veins travel above and below the common tendinous ring, respectively. The remaining options first traverse through the superior orbital fissure and travel through the CTR en route to the globe.

C: Muscle of riolan is the most superficial portion of the orbicularis oculi and is responsible for keeping the eyelid adhered to the globe.

A: The palpebral portion of the orbicularis oculi is responsible for spontaneous and reflex blinking. Voluntary blinking also includes the orbital portion of the orbicularis oculi

E: Palpebral conjunctiva and within caruncle are two sites of mucous production

B: Preauricular nodes – the site of palpation in cases of red eye. Medial conjunctival lymphatics travel to the submandibular nodes.

C: The corneal ENDOTHELIUM has the most mitochondria to supply energy to the Na/K pumps that maintain corneal water concentration.

A,C,E: Note the sizes above. Bowman’s is about 10um and Descemet’s begins at 5um and increases to about 15um with age.

E. Bergmeister’s Papillae can remain at the optic nerve. Mitterndorf and Epicapsular star are lens findings. Cloquet’s canal is within the vitreous. Weiss ring is the consequence of a posterior vitreous detachment of the optic nerve.

D. Anterior border layer is the primary contributor to eye color with trace input from the iris stroma.

B: Fetal nucleus is the only site of Y-sutures. The embryonic nucleus contains the most mature fibers.

B. The CRA has networks within both the Nerve Fiber Layer and the Inner Nuclear Layer. Dot and blot hemes are seen in the OPL as bleeding from INL leaks down layers.

E. Anterior iris epithelium – the rest of the options are composed of connective tissue

C. Plica Semilunaris allows for movement WITHIN the globe. The fornix and caruncle are location and redundant tissue, respectively. Mueller’s is responsible for lifting the eyelid. The muscle of riolan is responsible for keeping the eyelid adhered to the globe.

C. Pterygopalatine innervates the lacrimal gland to stimulate aqueous secretion.

C. The outer nuclear layer in the retina contains all the cell bodies of the photoreceptors.

B. The lens zonules begin their course from the pars plana and traverse to the posterior lens capsule to participate in accommodation.

B. The uvea is made up of iris, ciliary body, and the choroid.

D. The average human eye is about 24mm in length.

D. The INL is not found in the foveola. The six retinal layers in the foveola include: RPE, PRs, ELM, ONL, Henle’s, ILM

A: The weakest point of attachment is found at the macula. From weakest to strongest: Retinal vessels, Macula, Optic Nerve, Posterior lens, Ora Serrata/Vitreal Base. A PVD is most likely to occur at the base.

E. All of the above are correct. It is important to understand the general pathways innervation travels to the orbit and adnexa. Try to draw out these pathways with blanks that you can fill in and erase later.

A, B, D: The lateral rectus is unique in that it is the only nerve innervated by CN VI. Nerve innervation begins in the pons and travels past the precarious skull process which is more susceptible to damage from increased cranial pressure (vs. trauma). Unlike the other extraocular muscles, the lateral rectus has two origins on the annulus of zinn and receives blood supply from only one artery.

A: The recti muscles are primary facilitators of movement when the eye is turned out at 23 degrees. The obliques are responsible for elevation and depression when the eye is turned in at 51 degrees. Remember O’s to the nose.

D. Although inflammation does cause a widening of meibomian ducts, meibum that has become more viscous will block the further secretions. This blockade leads to acinar atrophy, a primary cause of dry eye.

C. Zonula Occludens/Adherens are responsible for tight barriers. Desmosomes maintain structure integrity. Hemidesmosomes are responsible for connecting cells to their basement membranes. Gap junctions serve a role in small ion transport and cell-cell signalling. Keratocytes are cells responsible for structural integrity of the cornea.

A: Melanopsin is found in the intrinsically photosensitive ganglion cells. These cells are thought to be regulators of the circadian rhythms found in mammals.

A. Vitamin A is the main component of opsins. Vitamin B can be found in all cells and usually depleted in alcoholics. Vitamin C is important in collagen synthesis, antioxidants, wound healing, bone formation, and many other functions. Vitamin D is supplied by the sun and helps in digestion. Vitamin E is an antioxidant found in vapes that in conjunction with nicotine, can increase the likelihood of developing cancer.