orbit Flashcards
Describe the flow of aqueous humor.
The ciliary processes are continuously secreting aqueous humor.
The iris is what separates the chambers.
Humor travels from the posterior chamber to the anterior chamber
Then they travel through the canal of schlemm and are reabsorbed.
No reabsorption can lead to increase of intraocular pressure - glaucoma.
Describe accomodation.
used to see closer objects
The lens is an elastic structure and pulled by suspensory ligaments connected to the ciliary muscle.
The lens is usually stretched out. When can object gets closer. The ciliary muscle contracts and that lessens the slack in the ligaments.
This allows the lens to get thicker in the middle, refract more light so it reaches the fovea.
Besides accomodation, what are the two other near reflexes?
- Pupillary constriction - to let in less light
2. Convergence - the medial rectus muscles contract
What is presbyopia?
Loss of elasticity. So even though the ciliary muscle contracts, the lens doesn’t return to its original state.
What is the innervation of the eye. What goes through the orbit canal, suprorbital fissure, inferior orbital fissure
- –Optic canal:——
1. Optic nerve
2. Opthalmic artery - one branch is the central artery of the retina - —-Superior Orbital Fissure—
1. Oculomotor nerve (III)
a. superior division - somatic motor innervation to the levator palpebrae superioris and the superior rectus
b. inferior division - contains all of the preganglionic parasympathetics and innervates the inferior rectus, medial rectus and inferior oblique
- Trochlear nerve (IV)
- Opthalmic division of Trigeminal (V1)
a. frontal - general sensation to the face
- supraorbital
- supratrochlear
b. lacrimal nerve - general sensation to the face
c. nasociliary
- sends a branch through the sensory root
- sends a branch into the long ciliary nerve - Abducens nerve
- Superior opthalmic vein - joins the cavernous sinus
- —-Inferior orbital fissure—–
1. inferior ophatlmic vein
2. infraorbital nerve (V2)
3. Zygomatic (V2)
What five muscles are innervated by autonomic?
- Ciliary muscle - parasympathetic
- Constrictor pupillae muscle - parasympathetic
- near reflex—— - Dilator pupillae muscle - sympathetic
- Smooth muscle of the levator palpebrae - sympathetic
- Lacrimal gland - parasympathetic and sympathetic.
What are the extraocular muscles and their innervations?
- Levator palpebrae which elevates the eyelid
motor: oculomotor
Smooth muscle: sympathetic - Medial rectus - oculomotor nerve
- Lateral rectus - abduction of the eye - abducens nerve
- Superior rectus - elevation and adduction of the eye - oculomotor
- Inferior rectus - depression and adduction of the eye
- Superior oblique - depression and abduction of the eye - *trochlear nerve
- Inferior oblique - elevation and abduction of the eye - oculomotor
Describe the pathway of nerves with the ciliary ganglion.
with the pathway of the sympathetics
- Nasociliary gives off a long ciliary nerve which goes to the eyeball.
- then a branch goes through the sensory root into the ciliary ganglion… - The sympathetics all come from T1, synapse in the superior cervical ganglion and then travel along the carotids. Then into the sympathetic root and through the ciliary ganglion….
- Parasympathetic parasympathetics travel with the inferior division of the oculomotor nerve and then enter the motor root, synpase in the ciliary ganglion…
These three all reach the eyeball by traveling through the short ciliary nerves.
- Somatic motor continues in the inferior divison to innervate the inferior rectus, medial rectus, inferior oblique.
What are the three conjunctivas?
- Palpebral conjunctiva - under the the eyelids
- Conjunctival sac - where tears go and gets sweeped medial to the nasolacrimal duct.
- Bulbar conjunctiva - covers the eyeball.
