OPT 114 (Ocular Anatomy): ORBIT (BONES FORAMINA FISSURES ETC)

Temporal Bones of the Skull

form the sides and base of the cranium

Two parts of the skull

Cranium and face

Sutures

These are the areas where bones meet (look like seams)

Sinuses

Air filled cavities within bones

frontal bone of skull

Forms anterior portion of cranium, anterior floor, and superior part of the face

Parietal Bones

Form the roof and lateral sides of the skull

occipital bone (skull)

forms the back part of the skull and the base of the cranium

sphenoid bone

forms part of the base of the skull and parts of the floor and sides of the orbit. (Butterfly shape)

3 parts of sphenoid bone

Body of sphenoid, lesser wings, greater wings)

greater wing of sphenoid bone

Protects from lateral aspect of body

lesser wing of sphenoid bone

protects from anterior aspect of body

body of sphenoid bone

houses pituitary gland in a depression called the sella turcica

ethmoid bone

forms part of the posterior portion of the nose, the orbit, and the floor of the cranium

4 parts of the ethmoid bone

Vertical (perpendicular plate) - forms nasal septum

horizontal (cribriform plate)- olfactory nerves pass through

labyrinths (2)- house ethmoidal sinuses

palatine bone

Extends from hard palate to orbital floor

lacriminal bone

located along the medial wall of the orbit

nasal bone

forms the bridge of the nose

inferior conchae

Located along lateral wall of nasal cavity

Vomer

forms the posterior part of the nasal septum

Zygomatic Bone

forms lateral part of cheekbone and the lateral wall and floor of the orbit

Maxillary Bone (maxilla)

Forms upper jaw, the cheek, hard palate, lateral wall of nasal cavity and the floor of the orbit

Mandible

Forms the movable lower jaw

orbit

contains globe, connective tissue, extra ocular muscles, orbital nerves, blood vessels and fat

7 bones of the orbit

Frontal, palatine, lacrimal, zygomatic, maxillary, sphenoid, and ethmoid

roof of orbit

-lesser wing of sphenoid bone

-orbital plate of frontal bone

Floor of orbit (weakest wall in orbit)

-orbital process of palatine bone

-orbital surface of maxillary bone

-zygomatic bone

medial wall of orbit (thinnest wall in the orbit)

formed by ethmoid, maxillary, lacrimal, and sphenoid

lateral wall of orbit (strongest area in the orbit)

formed by the zygomatic bone and greater wing of sphenoid bone

paranasal sinuses

Air filled pockets that reduce the weight of the skull and filter the air we breathe

maxillary sinus

inferior to orbits, largest sinus

sphenoid sinus

Posterior and medial to orbits

ethmoid sinus

medial to orbit

frontal sinus

superior to orbit

sinusitis

inflammation of the sinuses

foramen (foramina)

hole or opening in the bone

Function of the Foramen

allows entrance and exit of nerves and vessels in and out of orbit

optic foramen (canal)

between lesser wing and body of sphenoid bone. Opening between the orbit and cranial cavity

supraorbital foramen

opening above each orbit allowing blood vessels and nerves to pass

infraorbital foramen

opening under the orbit carrying the infraorbital nerves and blood vessels the the nasal region

fissure

long, narrow opening in bone allowing entrance and exit of nerves and vessels in and out of the orbit

Fossa

shallow depression in bone

Traveling to the infraorbital foramen

Infraorbital nerve CN V2, artery and veins pass through the inferior orbital fissure and continue along the infraorbital groove to pass through the infraorbital canal and infraorbital foramen

superior trochlear foramen/notch location

located in frontal bone, medial to the supraorbital foramen)

Superior trochlear foramen

CNV1 (supratrochlear nerve), artery, and vein pass through the foramen/notch

Lacrimal fossa (for the lacrimal sac)

located medially and formed by lacrimal bone and frontal process of maxilla. separated from the orbit by the orbital septum

Lacrimal fossa (for the lacrimal gland)

located in the frontal bone, house of the lacrimal gland

inferior orbital fissure

lies between floor of orbit and lateral wall

Nerves and vessels that pass through the infraorbital fissure

-Inferior ophthalmic vein

-zygomatic nerve (CN V2)

-infraorbital nerve, artery, and vein (CN V2)

Supraorbital Fissure

lies between the greater and lesser wings of sphenoid (slightly nasal and posterior of orbit)

Common tendinous ring (Annulus of Zinn)

fibrous structure that the rectus muscles arise from

Nerves that pass through superior orbital fissure and common tendinous ring

-Superior and inferior division of oculomotor nerve CN III

- Nasociliary Nerve (CN V1)

-Abducens Nerve ( CNVI)

Nerves that pass through superior orbital fissue and above the annulus of zinn

-Superior Ophthalmic Vein

- Trochlear Nerve ( CN IV)

- Lacrimal Nerve (CN V1)

-Frontal Nerve (CN V1)

CN V- cranial nerve 5

V1- ophthalmic

V2- maxillary

V3- mandibular

Orbit contents

globe, connective tissue, extraocular muscles (EOMS), orbital nerves, blood vessels, and fat

Globe (eyeball) 3 coats

outer fibrous layer

middle vascular layer

inner neural layer

outer fibrous layer of eye

sclera and cornea

middle vascular area of eye

iris, ciliary body, choroid (uvea)

inner neural layer of eye

retina

anterior chamber of eye

between the iris and cornea

posterior chamber of eye

between ciliary body and lens

The vitreous chamber of the eye

back half of the eye

Tenon's Capsule/Bulbar Fascia

sheet of dense connective tissue that covers the sclera

anteriorly merges with the sclera and conjunctiva at limbus but posteriorly continuous with dural sheath of ocular nerve

orbital septum (palpebral fascia)

sheet of dense connective tissue that extends the rim of the orbit to the tarsal plate . keeps orbital fat in place

-prevents facial, eyelid, nasolacrimal system infections from entering the orbit

The tarsal plate of the eyelid ________.

is connected to the levator palpebrae

Periorbita (Orbital fascia, Periosteum)

Sheet of dense connective tissue that covers the bones of the orbit

attachment site for muscles, tendons, and ligaments

provides support structure

Whitnall's ligament (superior transverse ligament)

transverse dense connective tissue provides support and maintains spatial relationships between anatomic structures in the superior orbit

What forms the Whitnall's ligament?

condensation of the levator muscle

Lockwood's Ligament (Suspensory ligament)

transverse dense connective tissue located in the inferior orbit, providing support for anatomic structures in the inferior orbit

medial check ligament

- transverse dense connective tissue that is an expansion of the sheath of the medial rectus

- attaches to lacrimal bone

- prevents overaction of medial rectus

lateral check ligament

- transverse dense connective tissue that is an expansion of the sheath of the lateral rectus

- attaches to zygomatic bone

- prevents overaction of lateral rectus

orbital septum system

web of interconnecting connective tissue septa

-anchors and supports EOMs, nerves and blood vessels

orbital nerves

II optic nerve, III oculomotor, IV trochlear, V1 ophthalmic, V2 maxillary, VI abducens

extraocular muscles

control movement of globe

recti muscles of eye

Medial Rectus (MR)

Lateral Rectus (LR)

Superior Rectus (SR)

Inferior Rectus (IR)

Oblique muscles of the eye

Superior Oblique (SO)

Inferior Oblique (IO)

levator palpebrae

elevates eyelid

Superior and inferior tarsal muscles

controls movement of eyelid

orbital fat

cushions eye, protects vessels and nerves of orbit

-surrounds ON

-separated muscles in the orbit from the orbital walls

Preaponeurotic Fat Pad

held in place by orbital septum