Orbit I and II Flashcards
What bones make up the outer rim of the orbit?
- Frontal
- Zygomatic
- Maxillary
Inside of the orbit, which two bones make up the medial wall.
- Lacrimal bone is located on the anterior aspect of the medial wall
- Ethmoid bone makes up the majority of the medial wall.
What makes up the Apex of the orbit?
The Optic Canal
What makes up the Lateral Wall of the orbit?
Zygomatic Bone
Sphenoid Bone
Frontal Bone
What makes up the Roof of the orbit?
Frontal Bone
Sphenoid Bone
What makes up the Medial wall of the orbit?
Ethmoid Bone Lacrimal Bone Frontal Bone Maxillary Bone Sphenoid Bone
What is the mucocutaneous junction?
Is a junction where the outermost layer of the skin around the eyelid becomes continuous with the palpebral conjuctiva.
What is the palpebral conjuctiva?
It is the mucos membrane on the inside of the eyelid.
What is the function of the orbital (bulbar) conjuctiva?
It serves as a protective covering for the eye itself.
Does the palpebral conjunctiva become continous with the orbital (bulbar) conjuctiva?
Yes.
What is the palpebral fissure?
It is the space between the upper and lower lids, bounded by the upper an lower palpebral margins.
Where do the palpebral margins meet?
At the canthi (angles)
Medial canthus
Lateral canthus
What are the seven layers associated with the eyelid?
- Skin
- Subcutaneous connective tissue
- Muscular layer
- Submuscular layer
- Tarsal Plate
- Tarsal Glands
- Palpebral Conjunctiva
What is Horner’s Syndrome?
It is a lesion to the superior cervical sympathetic ganglion.
What does Horner Syndrome result in? What will the patient present with?
It results in paralysis of the Tarsal muscles on the effected side.
The patient will present with:
Ptosis
Meiosis
Anhydrosis
What is Ptosis?
Drooping of the eyelid
What is Meiosis?
Small pupil
What is Anhydrosis?
Lack of sweating and reddening of the skin on the affected side.
What is the larger medial angle of the eye known as?
The lacrimal lake
What is the lacrimal caruncle?
It is the fleshy elevation seen in the medial angle of the eye within the lacrimal lake.
What does the lacrimal caruncle contain?
Sweat glands
Sebaceous glands
Cilia
These glands are responsible for the yellow and white secretion sometimes found in the eye upon arising after a nights sleep.
Plica semilunaris
A connective tissue band that separates the sclera from the lacrimal lake
Where is the lacrimal gland located?
At the superolateral aspect of the orbit
Components of the lacrimal gland?
Palpebral portion - lies close to the eye on the inner surface of the eyelid. it can be seen if the eye is everted.
Orbital portion- Portion that contain the interlobular ducts.
What is the route of tear secretion.
Tears secreted from the gland collect in the superior fornix of the upper lid, and pass over the eye surface.
Blinking aids in this process.
What kind of cells exist in the lacrimal gland. What do they secrete? What is the function?
Serous cells that secrete a watery solution of bacteriocidal enzyme lysozymes.
It provides nutrients and dissolved oxygen to the cornea
- Puncta larimali
- Lacrimal canaliculus
- Lacrimal sac
- Nasolacrimal duct
- Drain opening
- Duct
- Collection of fluid
- Drainage to nasal sinus
The motor fibers to the lacrimal gland are what in nature? Where do these fibers arise from?
Parasympathetic. They arise from the 7th cranial nerve
What is the specific branch of CN VII that travels to the lacrimal gland?
The greater petrosal nerve.
What is the course of the greater petrosal nerve?
The greater petrosal nerve courses within the hiatus for the facial nerve to the middle cranial fossa.
It continues across the foramen lacerum where it is met by the deep petrosal nerve. Together these two nerves form the nerve to the pterygoid canal.
The nerve to the pterygoid canal passes through the pterygoid canal it then courses into the pterygoid fossa to the pterygoplatine ganglion.
The postganglionic parasympathetic fibers then rejoin with the sympathetic fibers and then join the maxillary nerve (V2) and follows its zygomaticotemporal branch anteriorly.
These fibers then join the lacrimal branch of (V1) and follow it to the lacrimal gland.
What type of fiber does the deep petrosal nerve carry?
Sympathetic fibers
What two nerves make up the nerve to the pterygoid canal?
The greater petrosal nerve and the deep petrosal nerve.
What nerve synapses in the pterygopalatine ganglion?
Only the parasympathetic fibers of the greater petrosal nerve.
Which muscles originate from the anulus tendineus?
The recti muscles:
- Superior rectus
- Inferior rectus
- Medial rectus
- Lateral rectus
The anulus tendineus is medially placed and therefore the muscles must travel laterally as well as anteriorly to reach the eye.
Which muscles do not originate from the anulus tendineus? Where do they originate from
- Superior oblique : Sphenoid
- Inferior oblique : Maxilla
- Levator palpebrae supeiroris : Sphenoid
What is the anulus tendineus?
A fibrous ring which encircles the junction of the superior and inferior orbital fissures and the optic canal (optic nerve).
Are all 6 extraocular muscles functioning at all times?
Yes!
What are the division of the occulomotor nerve?
Superior division
Inferior division
What muscle does the superior division of the occulomoter nerve innervate?
- Levator palpebrae superioris
2. Superior Rectus
What muscle does the Inferior division of the occulomoter nerve innervate?
- Medial Rectus
- Inferior Rectus
- Inferior Oblique
It also carries parasympathetic fibers to the ciliary ganglion.
Which division of the occulomotor nerve carries parasympathetic fibers to the ciliary ganglion?
Inferior division
What oculomotor muscle does the trochlear nerve innervate?
Superior oblique muscle
What oculomotor muscle does the abducent nerve innervate?
Lateral rectus muscle
What is the “chemical” mneumonic for occulomoter muscles and their nerve innervations?
LR6, SO4, AO3
Which occulomoter muscle abducts the eye?
The Lateral rectus muscle
What type of information does the optic nerve provide?
Sensory information for vision from the retina to the CNS
What nerve is the largest nerve in the orbit.
Hint: It is covered by meninges
The optic nerve
What type of information does the opthalmic nerve provide?
It supplies sensory information to the orbit and external eye.
What are the three main branches of the opthalmic nerve?
- Lacrimal nerve
- Frontal nerve
- Nasociliary nerve
What are the two branches of the frontal nerve?
- Supratrochlear nerve
2. Supraorbital nerve
What are the branches of the Nasociliary nerve?
- Communicating branch to the ciliary ganglion
- Long ciliary nerves
- Posterior ethmoidal nerve
- Anterior ethmoidal nerve
- Infratrochlear nerve
What type of information does the lacrimal nerve provide?
- sensory innervation to the lacrimal gland
- Sensory innervation to the lateral aspect of the eye
- Sensory information to the upper and lower palpebrae
What type of information does the supratrochlear nerve provide?
supplies sensory innervation to the skin above the medial canthus and a portion of the scalp.
What type of information does the supraorbital nerve provide?
supplies the superior palpebra and the scalp above. Note that the supraorbital nerve is a direct continuation of the frontal nerve that exits the orbit via the supraorbital foramen
What foramen does the supraorbital nerve exit through?
The supraorbital foramen
What nerve is the terminal branch of the nasociliary nerve?
Infratrochlear nerve
Where is the ciliary ganglion located?
Between the optic nerve and the lateral rectus muscle.
What type of fibers run through the ciliary ganglion?
- Sensory and sympathetic fibers run through the ganglion without synapsing in it.
- Parasympathetic fibers from the oculomotor nerve also reach the ganglion and they are the ONLY ones that synapse there.