Anatomy: The Orbit and the Eye Flashcards
Where is the orbital septum located?
Extends from either tarsus to the orbital margin
What is indicated by the arrow?
Superior orbital fissure
What is indicated by the arrow?
Orbital plate of frontal bone
What is indicated by the arrow?
Superior tarsal plate
What is the function of the superior and inferior tarsus?
Form the scaffolding of the eyelid
Which nerve supplies the orbicularis oculi muscle?
CN VII (facial nerve)
What is indicated by the arrow?
Infraorbital foramen
Describe the anatomical features of the orbit which result in a blowout fracture following blunt force trauma to the eye
The medial and inferior walls of the orbit are the weakest, with the contents herniating into the ethmoid and maxillary sinuses respectively
Name the three parts of the orbicularis oculi muscle
Palpebral, lacrimal and orbital
What is indicated by the arrow?
Tendon of levator palpebrae superioris (LPS) muscle
What is the function of the lacrimal canaliculi?
Small channels in each eyelid that drain lacrimal fluid from the lacrimal puncta to the lacrimal sac
What is indicated by the arrow?
Medial palpebral ligament
Name the structure which transmits the zygomatic branch of the maxillary nerve, the inferior ophthalmic vein, and sympathetic nerves
Inferior orbital fissure
What is an orbital rim fracture?
Fracture of the bones forming the outer rim of the bony orbit, usually occurs at the sutures joining the three bones of the orbital rim (maxilla, zygomatic and frontal)
What is indicated by the arrow?
Inferior tarsus
What is indicated by the arrow?
Supraorbital notch/foramen
What is indicated by the arrow?
Orbital plate of ethmoid bone
What is indicated by the arrow?
Orbital septum
What is indicated by the arrow?
Optic canal
What are the Meibomian glands?
Glands located in the tarsal plates which secrete an oily lipid substance that slows the evaporation of the eye’s tear film and prevents the eyelids from sticking together when closed
Name the structure which transmits the optic nerve and ophthalmic artery
Optic canal
What is the function of the lacrimal part of the orbicularis oculi muscle?
Involved in the drainage of tears
What is indicated by the arrow?
Levator palpebrae superioris (LPS) muscle
What is indicated by the arrow?
Orbital part of the orbicularis oculi muscle
What is the function of the orbital part of the orbicularis oculi muscle?
Tightly closes the eyelids
Describe the flow of lacrimal fluid
- Lacrimal fluid produced by the lacrimal gland
- Fluid washes over the eye and is pushed towards the medial angle
- Once the fluid gets to the medial angle it drains through the lacrimal puncta
- Eventually the fluid reaches the inferior meatus
What is the function of the palpebral part of the orbicularis oculi muscle?
Gently closes the eyelids
Where is the axis of the orbit located?
Anteriolaterally
What is indicated by the arrow?
Lacrimal gland
What is a blowout fracture?
Refers to partial herniation of the orbital contents through one of its walls, usually occurs via blunt force trauma to the eye
How many bones form the orbit?
7
Name the bones which form the lateral wall of the orbit
Zygomatic and sphenoid (greater wing)
Name the bones which form the floor of the orbit (inferior wall)
Maxilla, palatine and zygomatic bones
The orbit can be thought of as a _______ structure, with the apex pointing posteriorly and the base situated anteriorly
Pyramidal
The lacrimal gland produces lacrimal fluid as a result of parasympathetic innervation by CN ____
VIII
Name the structure which transmits the lacrimal, frontal, trochlear, oculomotor, nasociliary and abducens nerves, and the superior ophthalmic vein
Superior orbital fissure
What is indicated by the arrow?
Nasolacrimal duct
What is indicated by the arrow?
Canaliculi
What is the function of the orbital septum?
Helps prevent spread of infection between superficial and deep parts of the orbit
Where is the axis of the eye directed?
Anteriorly
Name the bones which form the roof of the orbit (superior wall)
Frontal bone and sphenoid (lesser wing)
What is indicated by the arrow?
Lacrimal sac
What is indicated by the arrow?
Palpebral part of the orbicularis oculi muscle
Which tarsal plate acts as the attachment site of the levator palpebrae superioris?
Superior tarsus
What is indicated by the arrow?
Superior tarsus
Where are the tarsal plates located?
Deep to the palpebral region of the orbicularis oculi muscle
What is indicated by the arrow?
Lateral palpebral ligament
Name the bones which form the medial wall of the orbit
Ethmoid, maxilla, lacrimal and sphenoid bones
What are the tarsal plates composed of?
Dense connective tissue
