Histology - Eye & Ear

Front 1

What are the 3 layers of the eye?

Back 1

Outer Fibrous, Middle vascular, Inner nervous

Front 2

What are the 3 layers of the Sclera?

Back 2

Episcleral, Substantia propria, suprachoroidal lamina

Front 3

What is Tenon's Space?

Back 3

Space between episcleral and substantia propria layers - allows eye to rotate freely

Front 4

What is the Canal of Schlemm and where is it located?

Back 4

Aqueous humor drains into ciliary veins here - sclerocorneal junction

Front 5

What are the 6 layers of the cornea?

Back 5

Anterior corneal epithelium (stratified squamous with microvilli on superficial cells for protective tear coating- 6 layers)
Bowman's Membrane - homogenous collagen fibers (stability, strength of cornea)
Corneal Stroma - Mainly collagen I but also has types III, V, VI. Parallel arrangement of collagen fibers gives transparency

Front 6

What is Decemet's Membrane?

Back 6

Posterior limiting lamina of cornea with homogenous collagen filaments

Front 7

What are the two layers of the choroid?

Back 7

Choriocapillary, Bruch's Membrane (between retinal pigment epithelium & choroid)

Front 8

What are the major components of the iris?

Back 8

Anterior limiting membrane - incomplete & fenestrated, stellate fibroblasts
Stroma - collagen, fibroblasts, melanocytes (eye color)
Pigmented posterior epithelium
2 muscles - dilator pupillae, sphincter pupillae

Front 9

What is the nervous innervation for each of the iris muscles?

Back 9

Sphincter pupillae - CN III
Dilator pupillae - Sympathetics

Front 10

Describe the retinal layers

Back 10

Outer pigment epithelium and inner sensory retina
Stratified layer of nervous cells

Front 11

Explain Retinal Detachment

Back 11

Separation of photoreceptor layer from pigment layer
If not re-attached, degeneration of rods and cones

Front 12

What the the layers of the retina from inside to outside (where light hits)?

Back 12

Inner limiting membrane - Optic nerve layer - ganglion cell layer - inner plexiform (synapses between ganglion cells and bipolar cells) - inner nuclear (bipolar/horizontal cells) - outer plexiform (synapses between horizontal cells & photoreceptors) - outer nuclear (rod/cone granules)- outer limiting - rods & cones - pigment cell layer

Front 13

Describe the retinal pigment epithelium

Back 13

basement membrane blends with Bruch's membrane
Site of Vit A esterification
Microvill surround photoreceptors and have phagocytic function
Blood-retinal barrier

Front 14

What are the different parts of a photoreceptor cell?

Back 14

Outer segment (photoreceptor disk - contains photosensitive chemicals), modified cilia (connects segments), inner segment, nuclear region, synaptic region

Front 15

What is a major structural difference between rods and cones?

Back 15

Rods have a cylindrical outer segment while cones are more pointed

Front 16

What are major differences between rods and cones?

Back 16

Cones - thick, short, conical outer segment, concentrated in fovea, photopigment is iodopsin
Rods - sense light intesity, more in the periphery, photopigment is rhodopsin

Front 17

What are Muller's Cells and where are they found?

Back 17

Retinal support cells that form outer limiting membrane and rest on the inner limiting membrane,

Front 18

What is unique about the macula area of the retina?

Back 18

Only contains cones
Yellow color due to xanthophil pigment of ganglion cells
One photoreceptor to one ganglion

Front 19

Blood supply of Retina?

Back 19

Artery & vein enter with optic nerve
Form a plexus of capillaries between vitreous and inner limiting membrane
Rods & cones supplid by choroidal vessels
Layers 1-5 - Chorocapillary supply
Layers 6-10 - Central artery of optic nerve (continuous as retinal a.)

Front 20

Describe the different parts of the lens

Back 20

Capsule - type IV collagen, glycoproteins
Subcapsular epithelium - simple cuboidal, only on anterior side
Fibers - long & with crystallins

Front 21

Describe the flow of aqueous humor

Back 21

Ciliary body to anterior chamber to Canal of Schlemm at sclerocorneal junction for drainage
Abnormal drainage here causes intraoccular pressure to rise (Glaucoma)

Front 22

What layers make up the tympanic membrane?

Back 22

Outer layer - skin
Middle - connective tissue
Inner - simple cuboidal cells
Attached to malleus ossicle (linked to oval window)

Front 23

What are the contents of the middle ear?

Back 23

Ossicles - malleus, incus, stapes
Muscles - Tensor tympani, Stapedius - limit vibration of membrane & stapes during loud noise
Oval window, round window

Front 24

What makes up the Bony Labyrinth of the inner ear?

Back 24

Semicircular canals, vestibule, cochlea

Front 25

What makes up the Membranous Labyrinth of the inner ear?

Back 25

Semicircular ducts, Utricle, Saccule, Cochlear duct

Front 26

Describe the cochlear duct

Back 26

Bounded by Reissner's membrane (vestibular) and basilar membrane and stria vascularis. Contains the organ of Corti (containing neuroepithelial hair cells and support cells) which is covered by the tectorial membrane

Front 27

How does sound conduction work?

Back 27

The oval window sets up sound waves with cochlea. The vibration of the basilar membrane causes hair cells to bend by a shearing force as they pull on the tectorial membrane, causing firing of the cochlear nerve

Front 28

What is the Macula of utricle?

Back 28

Receives the utricular filaments of the vestibulocochlear nerve.

Front 29

What is the Helicotrema?

Back 29

It is the communication point of the scala tympani with the scala vestibuli at the apex of the cochlea

Front 30

What are the Cristae ampullares?

Back 30

similar to maculae, has a conical form called cupula
Receptors are sensitive to rotational acceleration
They are located in the ampulla of the semicircular ducts

Front 31

What are maculae?

Back 31

Receptors found on the walls of the saccule and utricle.
Characterized by specialized microvilli with a single cilium (kinocilium)
These receptors synapse with the vestibular component of CN VIII