Ocular Anatomy

V.S. 111

UAB School of Optometry

Timothy W. Kraft, Ph.D.

975-2885

twkraft@uab.edu

Goals for the Term

• Solid base of knowledge

• Comfort with Ocular terminology

• Basics of tissue structure & function– At the end of the course you can give

yourself a 3D guided tour of the eye and orbit within your mind’s eye.

Exam Schedule & Grading

• Midterm 45%

• Lab work sheets & hw (5%)

• Quizzes: Six, pick your best 5 for 10%

• and Final Exam 40%• some of Final is review

There will be 4 or 5 Lab sessions, attendance is mandatory

Sources of information

• The Human Eye structure and Function by Clyde Oyster

• Hand-outs, outlines including additional figures.

• CD’s of power point presentations for out of class review

Come to Class

Texts and Supplements

• Oyster (you buy this one) The Human Eye

• Williams & Warwick Functional Neuroanatomy of Man (copy provided)

• Snell & Lemp: Clinical Anatomy of the Eye (copy of selected figures provided)

Broad-based learning

• Power point presentations– Almost all lectures available on CD

• Hand out outline the lecture

• Study Guides

• When all else fails: RTB

Go to Class

Overview

• When the structure seems complicated , think FUNCTION– Imaging : OPTICAL CLARITY

– Information processing: pathways, adaptation

– Mobility: balance, strength, speed, MECHANICS

– Biological System: respiration, pain, protection

Terminology

• Rostral (toward top of head - rooster)

• Caudal (toward tail) cauda equina - horses tail

• Anterior - front - ventral

• Posterior- back - dorsal (dorsal fin)

• Medial (midline) {Nasal}

• Lateral away from midline (Temporal)

• Central -

• Peripheral- away from center

Basic components of eyeball

Scleral

outer

Vitreal

Inner

Eyeball: Optical Pathway

• Cornea

• Anterior Chamber

• Iris/Pupil

• Posterior Chamber

• Lens

• Vitreous

• Retina

Figure by Snell & Lemp

Eyeball: Layered tissues

• Protective epithelium

• Cornea/Sclera

• Choroid

• RPE

– All to protect/nourish the nervous tissue of retina/optic nerve

• Scleral/Vitreal

Figure by Snell & Lemp

The Orbit: Bone structuresBones: Those Latin names

Protecting the eye while serving its needs.

•VS111

•Aug 11, 2008

•Lect 1-2

Reasonable Goals

• Overall function is simple, but the details..– Name the bones,

– Know the construction of the orbit walls,

– Know the strong and weak points,

– What is in the orbit, what holds it there?

– What comes into, goes out of the orbit?

– What are holes (fissures, foramina) used for?

Skull has 22+ bones

• Cranium

– Parietal (2)

– Occipital

– Temporal (2)

– Sphenoid

– Ethmoid

• Face– Maxillary (2)

– Nasal (2)

– Inferior chonchae (2)

– Lacrimal (2)

– Palatine (2)

– Zygomatic (2)

– Mandible

– Vomer

•Frontal bone is part of both cranium & face

11 bones make up the orbits

• Single Bones

– Frontal Bone

– Ethmoid Bone

– Sphenoid Bone

• Paired Bones

– Maxillary

– Zygomatic

– Lacrimal

– Palatine

Bones of the skull

Lateral View of Skull

• Frontal

• Zygomatic

• Note temoral aspect of Sphenoid

• Maxillary

• Lacrimal

• Ethmoid

Sinuses exist in 4 Orbital Bones

• Air filled

• Mucosa lined

• Lighten bone

• Acustic

• Possible infection site

The basic shape of the orbit is a pyramid:

•The medial walls are parallel

•The depth is 1.5 x base

• The margin of the orbit {VERY STRONG}

– 4 cm wide

– 3.5 cm high

– 3 BONES• Frontal• Zygomatic• Maxillary

•4.5 cm deep

Terminology

• Fossa: shallow depression in bone

• Foramen (pl. foramina): hole(s) in bone

• Fissure: hole between adjacent bones

• Tubercle: bump attachment site

• Groove, canal, notch (as they sound)

A key figure of Chap 3

Let me help you get a 3D understanding of the structures summarized by this figure

•Naso

The orbital ceiling

•Frontal

•Bits of-

Sphenoid

Lacrimal Fossa

Trochlear Fossa

Supraorbital Notch

The Lateral Wall

•Not shown are:•Zygomatic foramen•Whitnall’s Tubercle

•Zygomatic

•Sphenoid

Bones of the skull

Now look at the Sphenoid

The Sphenoid Bone

• Butterfly

• (Owl like)

– Greater Wing

– Lesser Wing

– Pterygoid process

• Many Foramina

– Optic Foramen

– Sup. Optic Fissure

Lateral View of Skull

• Frontal

• Zygomatic

• Note temoral aspect of Sphenoid

• Maxillary

• Lacrimal

• Ethmoid

The Sphenoid Bone &

Occipital (at back)

Ethmoid (yellow)

Palatine (small red)

Maxillary(straight on view of structure shown on hand out - page 42)

•Now go back to lateral wall slide

The Lateral Wall

•Not shown are:•Zygomatic foramen•Whitenalls Tubercle

•Zygomatic

•Sphenoid

The Medial Wall

• Ethmoid

• Lacrimal

• Sphenoid

• Maxillary

The Orbit Floor

• Maxillary

• Zygomatic

• Palatine

Main components of fissures

Let me help you get a 3D understanding of the structures summarized by this figure

•Fig 3.2

Weakest bones are in the floor and medial wall of the orbit.

• Transmitted pressure through the tissues(?) or the sturdier bones causes blowout fractures.

•Lamina papyracia

Blowout fracture of the floor of maxillary bone.

Blowout fracture of the floor of maxillary bone. CT image

Blowout fracture of the ethmoid bone. CT image.

•esf ethmoid sinus fracture •mwf medial wall fracture

Connective tissues in the orbit

• All of the structures within the orbit have a connective tissue sheath– Around the Globe & muscles it’s call Tenon’s capsule

• If the globe is the palm and EOM fingers, then Tenon’s capsule is the glove.

– Lining the bones, it’s the periosteum• periorbita- a special name for orbit bone lining

– nerves, blood vessels have them too

• And they are interconnected making for a web of sheaths.

Two Views

• Tenon’s capsule

• Periorbita

A better view

Terminology

• Fossa: shallow depression in bone

• Foramen (pl. foramina): hole(s) in bone

• Fissure: hole between adjacent bones

• Tubercle: bump attachment site

• Groove, canal, notch (as they sound)

Soft tissue covering

• Surrounding the sclera is the episclera

– Connective tissue and blood vessels.

• Surrounding the episclera is Tenon’s capsule

– Another layer of connective tissue protecting the globe and making it slippery for movement within the orbit.

Soft tissue covering

• Check ligaments

– medial and lateral are most prominent but the inferior rectus and levator have them too.

• Superior transverse ligament

– Supports levator muscle (Whitnall’s Ligament)

• Suspensory ligament (of Lockwood)

– Connective tissue underneath the globe

Orbital infection

• Orbital cellulitis: infection of the tissues and fat pads behind/surrounding the eye, but not the eye itself

– 60% of orbital cellulitus is a secondary infection due to a sinus infection

Bone development• Dermal Bones, most of orbit

– Foci of osteoblasts differentiated from with the mesoderm

• Cartilage pre-formed bones: ethmoid and part of sphenoid. (Endochondral bone)– Chondrocytes form cartilagenous template of the final

bone

– Osteoblasts invade and differentiate into osteocytes

• Bone can restructure/repair itself– Osteoclast cell can breakdown boney matrix

• Permits growth of the skull and orbits