Eyes: Orbit and extraocular muscles Flashcards
Which structure helps support the anterior aspect of the orbit?
Orbital septum
Why does hyperthyroidism cause eye bulging?
It causes an increase in orbital fat volume, leading to the eyeballs being displaced anteriorly
The walls of the orbit are made up of which 7 bones?
Frontal
Ethmoid
Sphenoid
Maxilla
Zygomatic
Palatine
Lacrimal
A branch of CN Va emerges superior to the orbit via which structure?
Supraorbital notch
A branch of CN Vb emerges inferior to the orbit via which structure?
Infraorbital foramen
Which vessels are a potential route of infection spread from the eyeball to the cranial cavity? What is their route?
Orbital veins - they drain posteriorly into the dural venous sinuses
Blunt trauma to the eyeball or perimeter of the orbit can cause which pathology?
Orbital blowout fracture
Which 2 muscles open the eye and what is their innervation?
Levator palpebrae superioris - CN III
Superior tarsal - sympathetic
Which muscle closes the eye and what is its innervation?
Orbicularis oculi - CN VII
Which 6 muscles move the eye?
Superior rectus
Inferior rectus
Medial rectus
Lateral rectus
Superior oblique
Inferior oblique
Which structure acts as a “pulley” for the superior oblique muscle?
Trochlea
The trochlea acts as a pulley for which muscle that moves the eye?
Superior oblique
All skeletal muscles in the orbit, apart from two, are innervated by which CN?
CN III
The superior oblique muscle in the eye is innervated by which CN?
CN IV (trochlear)
The lateral rectus muscle in the eye is innervated by which CN?
CN VI (abducens)
Which CNs enter through the superior orbital fissure?
CN III
CN IV
CN Va
CN VI
Which eye muscle originates from the anterior and medial part of the floor of the orbit and sits like a hammock under the eye?
Inferior oblique
