Anatomy Flashcards
(35 cards)
What forms most of the roof of the orbit?
Orbital plate of the frontal bone
Name the bones and bony features that make up the bony orbit
Orbital plate of the frontal bone, supraorbital notch/foramen, lacrimal bone, orbital plate of the ethmoid bone, maxilla, infraorbital canal, zygoma, sphenoid bone, optic canal, supraorbital fissure
What does the supraorbital notch house?
The supraorbital nerve which is a branch of CN V1 (trigeminal)
Describe the areas of the orbital rim
Superior, inferior, medial, and lateral orbital margins
Superior margin sits more anteriorly than the inferior margin and the medial margin sits more anteriorly than the lateral margin
What gives the orbital rim is protective function?
It is very strong
The superior orbital margin sitting anteriorly to the inferior orbital margin
What is an orbital blowout fracture?
Which parts of the orbit are most likely to be affected by this and why?
A fracture of the orbit in which the orbital rim remains in tact
The medial wall and the orbital floor are most likely to be fractured because they are very thin.
Floor of the orbit is more likely to fracture than the medial wall because the medial wall contains sinuses which shoot to dissipate the force.
What is the most common bone affected in an orbital fracture?
Zygomatic bone
Which nerve might be damaged in a floor of orbit fracture and why?
Infraorbital nerve - this is because it travels through the infraorbital canal which is part of the maxilla which makes up the floor of the orbit.
What can happen if a fractured zygoma rotates medially?
The infraorbital neurovascular bundle can be damaged resulting in a general sensory deficit of the facial skin
Describe the orbicularis oculi
Muscle of facial expression so supplied by the facial nerve
Acts as the sphincter of the eye
Is in 2 parts: in one part the fibres surround the eyelids to ‘screw up’ the eyes; the fibres of the other part are within the eyelids and are used in blinking
What are the connective tissues in the eyelid?
Orbital septum, medial and lateral palpebral ligaments, superior and inferior tarsal plates, and the tendon of the lavatory palpebrae superioris muscle
What is the palebral fissure?
The space between the upper and lower eyelids
What is the orbital septum and what is its clinical importance?
A sheet of fascia attaching to the periphery of the orbital rim
It assists with preventing the spread of infection from superficial (periorbital cellulitis) to deep (orbital cellulitis)
Describe the superior and inferior tarsal plates
Made of very tense connective tissue and give shape to the eyelids
What do the medial and lateral palpebral ligaments do?
Attach eyelid to orbital rim
What are the tarsal glands and where are they located?
Lipid secreting glands which are located on the inside of the eyelid: anterior to the palpebral conjunctiva and posterior to the tendon of the levator palpebrae superioris muscle and orbicularis oris
what is the limbus?
junction between cornea and sclera - also known as corneoslceral junction
what is the conjunctival fornix?
where the conjunctiva is reflected off the sclera and onto the internal aspect of the eyelid
what is the lacrimal lake?
where tears gather before entering the puncta during blinking
describe the puncta and the inferior lacrimal papilla
inferior lacrimal papilla is the swelling around the puncta
the puncta is the opening into the nasolacrimal duct
what is the function of the conjunctiva?
the conjunctiva forms a defensive barrier to foreign bodies penetrating deep to it into the orbit
does the cornea have its own blood supply?
no, it is avascular
what is the nerve supply to the lacrimal gland?
CN VII - parasympathetic division
what are the superior and inferior lacrimal canaliculi?
small canals which drain into the lacrimal sac
