Ocular Anatomy - Exam 1

Ocular Anatomy

How long is an eyeball in diameter?

2.5 cm (1 in)

What portion of the eye is protected by the orbit?

5/6

What portion of the eye is not protected by the orbit?

1/6

Fibrous Tunic

Sclera and Cornea

Vascular Tunic

Iris, Ciliary Body, and Choroid

What is another name for Vascular Tunic

Uvea

Nervous Tunic

Retina = pigmented layer and neural layer

What is another name for the nervous tunic?

Retina

Cornea

• transparent coat

• curved

• helps focusing light onto the retina

The 5 layers of the cornea?

1. Epithelium

2. Bowman’s Layer

3. Stroma (thickest)

4. Descemet’s Membrane

5. Endothelium

Sclera

• white

• covers entire eyeball except the cornea

• gives the shape of the eyeball

• protects internal tissue

Canal of Schlemm (scleral venous sinus)

junction of sclera and cornea

Choroid

• posterior

• highly vascularized

• lines the internal surface of the sclera

• provides nutrients to the posterior surface of the retina

Ciliary Body

from the ora serrata to sclero-corneal junction (ciliary processes & ciliary muscles)

Ciliary processes

• secrete aqueous humor

• suspensory ligaments or zonular ligaments are attached here

Iris

• colored portion of the eyeball

• contains the pupils

• melanocytes and smooth muscles

• regulates amount of light entering the eye

Which muscle in involved in the constriction of the pupil?

Sphincter muscle

Which muscle is involved in the dilation of the pupil?

Dilator Muscle

Anterior Cavity

aqueous humor

Posterior Cavity

vitreous humor

Nervous Tunic (Retina)

• Beginning of the visual pathway

• RPE - retinal pigmented epithelium

• Neural layer (photoreceptors, bipolar cells, and ganglion cells)

Lens

• transparent

• avascular

• helps focus images on the retina

• Dives eyeball in two cavities (anterior and posterior)

How often does the aqueous humor get replaced?

Every 90 minutes

Eyelids consist of?

1. skin

2. muscle

3. glands

4. conjunctiva (palpebral and bulbar)

Function of the Eyelids?

1. shades eyes during sleep

2. protect the eye of excessive light and FB

3. Spread tears

How many muscles move each eyeball?

1. superior rectus

2. inferior rectus

3. lateral rectus

4. medial rectus

5. superior oblique

6. inferior oblique

When does the development of the eye begin?

fertilization of the ovum and continues until the early postnatal period

Parts of the neural tube?

1. Forebrain

   1. Telencephalon

   2. Diencephalon

2. Midbrain

3. Hindbrain

From what structure does the eye begin to form?

The wall of the diencephalon

When does the embryonic plate form?

3rd week of embryonic development

What three primary germ layers form the embryonic plate?

1. ectoderm

2. mesoderm

3. endoderm

Which germ layers are involved in the formation of ocular structures?

Ectoderm and mesoderm

Mesoderm

• notochord

• muscles

• mesenchyme (dermis, circulatory system, and connective tissue)

Ectoderm

• surface and neural ectoderm

• CNS (Brain and spinal cord)

• Epidermis (nail, skin, and nails)

Endoderm

• guts, glands, and inner lining of the digestive and respiratory tubes

• does not contribute to ocular development

On what day do the two neural folds begin to develop?

18th day

On what day does the neural tube finish developing?

22nd day

What is the neural ectoderm?

the lining of the neural tube

On what day does the optic vesicles form?

25th day

What structures form the optic nerve?

optic cup and optic stalk

what is the last structure to close

embryonic fetal fissure

what artery turns into the central retinal artery

hyaloid artery

what causes colobomas

if fetal fissure fails to close properly (in choroid, retina, optic nerve, eyelids, iris, and ciliary body)

• inferiors are the most common

optic cup divides into

1. the inner layer becomes:

   • the neural retina

   • non-pigmented ciliary body epithelium

   • posterior (inner) pigment epithelium of the iris

2. outer layer becomes:

   • retinal pigment epithelium

   • outer pigmented ciliary body epithelium

   • anterior iris epithelium or outer non-pigmented epithelium

in what week does the internal carotid artery enter the optic cup

5th week

what structure does the internal carotid artery become

hyaloid artery (primary vitreous )

when is the cloquet’s canal formed

2nd month (avascular secondary vitreous)

when do the zonular fibers begin to stretch form growing ciliary region towards the lens capsule

4th month

where do orbital fat and connective tissue derive from

neural crest cells (mesenchyme)

what embryonic tissue contribute to ocular tissues

1. surface ectoderm

2. neural ectoderm

3. neural crest (mesenchyme)

4. mesoderm

does endoderm contribute to ocular tissues

no

congenital cataract

tissue near the developing lens fail to induce the lens fibers to elongate

types of developmental remnants

1. bargemaster’s papilla

2. Mittendorf’s dot

3. visible Cloquet’s canal

4. pupillary membrane

bargemeister’s papilla

glial tissue that persist on the nerve head

mittendorf’s dot

pinpoint remnant of the hyaloid artery on the posterior surface of the lens

retinopathy of prematurity

due to the high oxygen concentration vessel growth increases but are “leaky” with poor formed endothelial tight junction

pupillary membrane

remnants of central portion of the pupillary membrane (spider webs)

how many bones are in the cranium & name them

8: POTSEF

1: Parietal bones (2)

2. Occipital bone

3. temporal bones (2)

4. Sphenoid Bone

5. Ethmoid Bone

6. Frontal Bone

How many bones are in the face & name them?

14: My Mouth’s Palate Never Liked Zucchini In Vinegar

1. Maxilla (2)

2. Mandible

3. Palatine (2)

4. Nasal bone (2)

5. Lacrimal bone (2)

6. Zygomatic bones (2)

7. Inferior conchae (2)

8. Vomer

Are the bones of the skull movable or immovable?

Immovable

What is the only movable join in the skull?

temporal mandible joint

sinuses

air filled cavity

what is the smallest bone in the orbit?

lacrimal bone

what bone forms the roof and sides of the cranium

parietal bones

what joins the parietal bones

sagittal suture

what bones does the parietal bone articulate with

1. posteriorly: occipital bone at the lambdoid suture

2. anteriorly: frontal bone at the coronal suture

3. inferiorly: temporal bones and the greater wing of the sphenoid bone

what bone forms the floor of the skull

occipital bone

inion

external occipital protuberance

foramen magnum

found in the occipital bone where the brain and spinal cord connect

what lies in the posterior cranial fossa

lobs of the cerebellum

what bones does the occipital bone articulate with?

1. temporal bone

2. parietal bone

3. sphenoid bone

ethmoid plate

rectangular box that contains a midline perpendicular plate

what perforates the cribriform plate in the ethmoid bone

olfactory nerves

what bones does the ethmoid bone articulate with?

1. superiorly: sphenoid bone

2. inferiorly: vomer

3. maxillary

4. lacrimal bones

what bone forms the base of the cranium?

sphenoid bone

what bones articulate with the sphenoid bone?

1. occipital bone

2. temporal bone

3. anteriorly: maxillary

4. inferiorly: palatine

5. superiorly: parietal bone & frontal bone

6. anteriorly: ethmoid

what joins the zygomatic bones to form the lateral walls of the orbit

sphenoid bone

sella turcica

depression on the superior cranial surface houses the pituitary gland

where is the optic foramen (canal) located

between the lesser and greater wing of the sphenoid bone

what passes through the foramen rotundum

maxillary nerve

what passes through the foramen ovale

mandibular nerve

what passes through the foramen spinosum

middle meningeal artery

what foramen are located in the sphenoid bone

1. optic foramen

2. foramen rotundum

3. foramen ovale

4. foramen spinosum

two portions of temporal bones

1. squamous

2. petrous

what forms the side of the cranium

squamous portion of the temporal bone

what bones does the squamous portion of the temporal bone articulate with

parietal bone and sphenoid bone

what bones does the petrous portion of the temporal bone articulate with

occipital bone

what houses the middle and inner ear structures

the petrous portion of the temporal bone

what process can be found in the temporal bone

1. zygomatic process

2. mastoid process

3. styloid process

what is btw. the mastoid process and the styloid process

styloidmastoid foramen

what nerve exists the skull through the styloidmastoid foramen

facial nerve

what bone is the carotid canal found

temporal bone

what artery passes through the carotid canal

internal carotid artery

what bone forms our forehead

frontal bone

which bones does the frontal bone articulate with

1. inferiorly: nasal bone, maxillae, zygomatic

2. superiorly: parietal bone, sphenoid bone, ethmoid bone, and lacrimal bone

what lies in the anterior cranial fossa

frontal lobes

what structures does the maxillary bone form

1. upper jaw

2. hard palate

3. lateral walls of nasal cavity

4. floor of both orbits

what bones does the maxillary bone articulate with

1. frontal

2. nasal

3. sphenoid

4. ethmoid

5. lacrimal

6. palatine

7. zygomatic