The orbit Flashcards
What are the bones that the orbit is made of? 7 bones
- frontal
- sphenoid: small and large wings
- lacrimal
- ethmoid
- maxilla
- zygomatic
- palatine
What are the 4 walls of the orbit?
Superior or roof of the orbit
inferior orbit or floor
Internal
External
The roof wall?
- Lesser wing of the sphenoid bone
- Frontal bone
What are the anatomical features in the roof wall?
- Lacrimal gland fossa
- trochlear fovae
How thick is the roof?
1 mm
The outer wall?
- The frontal
- the zygomatic
- the graeter wing
which wall is the thickest and strongest?
the outer wall
Anatomical features near the outer wall?
- Whitnall’s tubercle: attachment to the external palpebral ligament
The floor?
- the orbital process of the palatine bone
- the zygoma
- the pyramidal process of the maxilla
How thick is the floor?
0.5 mm
which floor is the fragile one?
The floor
The inner wall?
- the lacrimal bone
- frontal
- lateral surface of the sphenoid bone
- Ethmoid
What is the special feature of the lacrimal bone
- The posterior lacrimal crest:
anterior part: lacrimal sac
posterior part
What is the structure that is attached to the anterior lacrimal crest?
- the internal palpebral ligament
What are the part of orbital rim? - base
- The upper
- The lower
- the outer
- The inner
The upper orbital rim?
- Frontal
The outer orbital rim?
- Frontal
- zygomatic
The lower OR?
- The zygoma
- The maxilla
The inner orbital rim?
- Frontal
- maxilla
The orbital apex formed by?
the rectangular orbital surface of the sphenoid body
corresponds to the internal end of the superior orbital fissure
Where the optic canal is located?
- the small wing
The optic canal gives away to?
- the optic nerve and ophthalmic artery
Where the ZINN tendon is inserted?
- the suboptic tubercle: Between the optic hole and the wide part of the superior fissure
Where The superior orbital fissure is located?
- Between the Greater and lesser wing
What is the relation between ZINN ring and SOF
SOF is divided by the common tendinous ring
What passes by the SOF
- Inside the ZINN ring:
- nasal nerve
- occulumotor nerve
- Abducens nerve
- Outside the ZINN:
- trochlear nerve
- Frontal nerve
- Lacrimal nerve
What is the role of Inferior orbital fissure?
- connects the orbit with the pterygo-palatine fossa.
What is the role of Anterior and posterior ethmoidal holes?
Ethmoidal arteries and nerves ( Anterior and posterior)
The vascularization of the Orbit
- Ophtalmic artery +++: ICA
- Infra-Orbital artery: ECA
The venous return of the orbit?
Ophtalmic veins
What are the three segments of Ophthalmic artery?
- Intracranial
- Intracanalicular
- Intraorbital
The origin of ophthalmic artery?
- Anteromedial part of the internal carotid artery.
- Above the anterior clinoid process
The relation between the ophthalmic artery and the ophthalmic nerve?
- Intracranial: the artery connects with the underside of the optic nerve (separated by the dura mater).
- Intraductal: the artery travels below the optic nerve
- Intraorbital:
- Lateral optic : The artery at the lower part of the nerve
- Optic part: the artery crosses the optic nerve
- Medio-Optic: the artery is medial to the nerve.
What is the length of Intracranial segment?
3-15 mm
Where the orbital artery terminates?
the superior-internal angle of the orbit
What are the two groupes of Collateral branches of ophthalmic artery?
- Optic arteries
- Destinated to the appendages
What are the optic arteries?
- Central retinal arteries
- Short and long ciliary arteries
- Optic nerve arteries
What are the branches Destinated to the appendages?
- Supraorbital arteries
- Ethmoidal
- Lacrimal
- palpebral
- muscular
What are the two groups of the otic nerve arteries?
- From intracanal segment
- From Intraorbital segment
What is supplied by the Supraorbital artery?
- the levator muscles of the upper eyelid
What are the two groupes of the ethmoidal arteries
Psterior and Anterior
What are the two groupe of Palpebral arteries- For Eyelides
Inferior and superior < palpebral arches.
Termial branches of The OA?
- Angular artery: Anastomosis in the nose
- Frontal arteries
What about the External carotid system?
- Infraorbital artery
- Meningeolacrimal artery: middle menengeal artery
What is the area suppliest by the infraorbital artery?
around the upper orifice of the nasolacrimal duct
The venous vascularization of the Orbit
- The superior ophthalmic vein
- Middle ;;
- Inferior
What the 2 roots of the superior OV?
- Superior: frontal veins
- Inferior: angular veins
from where The middle OV comes?
- muscular artery: medial , lateral, Inferior recti
From where The Inferior OV comes?
- muscular arteries: superior oblique, lateral and inferior recti
