Contents of the Orbit Flashcards
Another name for Tenon’s capsule
Bulbar fascia (globe/ connective tissue)
Is tenon’s capsule vascular or avascular
Tenon’s capsule is avascular. Although vessels travel through the layer, no capillaries are formed within.
What does tenon’s capsule cover
The sclera and extra ocular muscles as they insert into the sclera.
Anteriorly, tenon’s capsule merges with the ___ at the limbus
Sclera and conjunctiva
Posteriorly, tenon’s capsule is continuous with the ___ of the optic nerve
Dural sheath.
This provides a strong barrier and prevents the spread of disease from orbit to eyeball/globe.
Dural sheath
Dense connective tissue that protects the optic nerve as it exits the eye.
What structure of the eye prevents spread of disease from the orbit to the eyeball?
Tenon’s capsule.
Another name for orbital septum
Palpebral fascia
Another name for palpebral fascia
Orbital septum
Where does the orbital septum/palpebral fascia originate?
The arcus marginalis
What is the orbital septum/palpebral fascia?
Sheet of dense connective tissue that extends the entire rim of the orbit to the tarsal plate.
It is continuous with the periosteum at the super and inferior orbital rim.
Anterior barrier of the orbit (holds fat in)
Separates the eyelids and lacrimal sac from the orbit
What structure keeps orbital fat in place
Orbital septum/palpebral fascia
What structure is continuous with the periosteum at the super and inferior orbital rim
The orbital septum/palpebral fascia
What is the periosteum called when it is in the orbit
Periorbitum
peri
around
What is the periorbita (periosteum/orbital fascia) continuous with anteriorly and posteriorly?
Anteriorly- Continuous with the periosteum of the facial bones and the orbital septum
Posteriorly- Continuous with the dural stealth of the optic nerve and forms the common tendinous ring.
What forms the common tendinous ring?
The periorbita/perostium/orbital fascia
What muscle type is the periobrbita?
Smooth muscle innervated by the autonomic system.
What is Whitnall’s ligament and where is it located
Dense connective tissue that is located in the superior orbit. It courses from the lateral orbit wall to the medial orbit wall.
Role of Whitnall’s ligament
Provides support and maintains the spacial relationships between anatomic structures in the superior orbit.
What is Whitnall’s ligament formed by
Condensation of the elastic fibers in the anterior sheath of the levator muscle- point where the levator muscle fibers end and the levator aponeurosis begins.
Role of lockwood’s ligament
Dense connective tissue that provides support and maintains spatial relationships between anatomic structures in the inferior orbit.
What does Lockwood’s ligament contribute to the formation of
Capsulopalpebral fascia.
What is lockwood’s ligament similar to?
Whitnall’s ligament. Both span the anterior orbit from lateral to medial walls and support/maintain the spacial relationships between anatomic structures in the superior or inferior orbit. They are both dense connective tissues.
Aponeurosis
Sheet/fan of fibrous tissue that takes the place of a tendon in flat muscles and has a wide range of attachment.
What is the medial check ligament?
A transverse dense connective tissue that is an expansion of the sheath of the medial rectus and then attaches to the lacrimal bone
Where does the medial check ligament attach too?
The lacrimal bone
What is the role of the medial check ligament
Prevents over-action of the medial rectus
Lateral check ligament
Transverse
Where does the lateral check ligament attach too?
The zygomatic bone
What is the role of the lateral check ligament
Prevents overreaction of the lateral rectus
What 4 ligaments form a supporting hammock-like formation for the globe?
Whitnall’s ligmanent (superior), Lockwood’s ligament (inferior), medial check ligament (medial) and lateral check ligament (lateral)
What is the lateral check ligament attached to?
It is a connective tissue that expands from the sheath of the lateral recuts muscle while the other side attaches to the zygomatic bone.
Orbital septum system
Web of interconnecting connective tissue septa
Organizes the orbital space surrounding the globe- anchors and supports extra ocular muscles, nerves, and blood vessels
Orbital nerves
II- optic nerve III- oculomotor IV- Trochlear V1- Trigeminal ophthalmic division V2- Trigeminal maxillary division VI- Abducens
CN III
Oculomotor
CN IV
Trochlear
CN VI
Abducens
Blood vessels of the eye
Ophthalmic artery and its branches
Superior and inferior ophthalmic vein and branches
Extraocular muscles
Recti muscles- medial rectus (MR), lateral rectus (LR), superior rectus (SR) and inferior rectus (IR)
Oblique muscles- Superior oblique (SO) and inferior oblique (IO)
List the 3 eyelid refractors and what do they do?
Levator palpeerde (moves upper lid) Muller's muscle (tarsal muscle) Capsulopalpebral fascia, which is not actually a muscle does the bottom lid.
Where is most of the fat located at in the eye
Apex. Surrounds the ON, separating it from the EOM’s. Also separates the muscles in the orbit from the orbital walls.
Space not occupied by orbital structures becomes filled with..
adipose tissue
Where are anterior fat pads located
Anterior superior orbit, there are 2. They are located anterior to the locator muscle. (pre-aponeurotic)
One is nasal and one is central. (There is not one temporal because that is where the lacrimal gland is located)
Anterior inferior orbit, there are 3. They are posterior to the orbital septum and anterior to the capsulopalpebral fascia.
Nasal, central and temporal.
