Eye and Orbit Flashcards
What bone forms the superior border of orbital margin?
Frontal bone
What bone forms the lateral border of orbital margin?
Zygomatic bone
What bones form the medial-anterior border of orbital margin?
Frontal bone and frontal process of Maxilla
What bone forms the medial-posterior border of orbital margin?
Lacrimal bone
What bone forms the roof of the orbit?
Frontal bone
What bone forms the floor of the orbit?
Maxilla
What bones forms the medial wall of the orbit?
Maxillary, lacrimal, ethmoid (lamina papricia), sphenoid (lesser wing)
What bones form the lateral wall of the orbit?
zygomatic, sphenoid (greater wing)
What are the 9 openings found within the orbit?
Supraorbital notch or foramen, Infaorbital foramen, optic canal, superior orbital fissure, inferior orbital fissure, infraorbital groove/canal, anterior and posterior ethmoid foramen, zygomatic canal, nasolacrimal duct
What nerve and corresponding action are associated with the orbital and palpebral part of the orbicularis oculi?
CN VII, closes eyelids
What nerve and corresponding action are associated with the levator palebrae superioris?
CN III, opens upper eyelid
What is the smooth muscle (under sympathetic control) portion of the levator palpebrae superioris?
Superior tarsal muscle
Which CN opens the eye?
CN III-you can think of this being a set of pillars keeping the eyelid open
Which CN closes the eye?
CN VII-you can think of “7” as being a hook that closes the eyelid
What is the name of the sac-like structure analagous to the vestibular (mucolabial) fold?
Conjunctival Sac of the conjunctivum
Which two sinuses are found just superior and inferior to the anterior portion of the orbit?
Frontal and maxillary sinuses
Which wall (medial or lateral) of the orbit is the strongest?
The lateral wall (this serves a protective function)
If orbital pressure becomes too great, which bone within the medial wall of the orbit is most likely to suffer a blow out fracture?
The lamina papricia of the ethmoid bone
What is the connective tissue “skeleton” of the eyelid?
tarsal plate
What is the name of the structure responsible for keeping the eyelids from sticking together?
tarsal glands (they create a fatty secretion)
What are the sebaceous glands of the eyelid?
Ciliary glands
Which part of the conjunctiva is continuous with the skin and very vascular?
Palpebral conjunctiva
Which part of the conjunctiva is continuous with cornea and transperent?
Bulbar conjunctiva
What nerves are responsible for the general sensory innervation of the upper eyelid?
V1-lacrimal (lateral), supraorbital, supratrochlear (medial) and infratrochlear (medial) nerves
What nerves are responsible for the general sensory innervation of the lower eyelid?
inferior palpebal nerve (one of the terminal branches of V2)
What vessels provide the blood supply to the upper eyelid?
opthalimic artery (lacrimal, supraorbital, dorsal nasal and supratrochlear arteries)
What vessels provide the blood supply to the lower eyelid?
inferior palpebral from maxillary artery and the superior labial artery (from the facial artery)
What is the pathway for tears (under parasympathetic control, CN VII)?
Tears from lacrimal gland–>superior and inferior puncta–>lacrimal canal–>lacrimal sac–>nasolacrimal duct–>nasal cavity–>empties into inferior meatus
Where is the choroid located?
between the sclera and retina
What are the two structures continuous with the sclera?
Cornea (continuous with the sclera) & dural sheath of the optic nerve
Which eye structure separates the anterior and posterior chambers of the eye?
The iris
What two structures define the anterior chamber of the eye?
Cornea–>anterior chamber–>iris
What two structures define the posterior chamber of the eye?
iris–>posterior chamber–> lens
What structure under parasympathetic control (CN III) closes to keep light out of the eye?
Sphincter pupillae
What structure under sympathetic control consists of radial muscles going out from the iris?
Dilator pupillae
What structure and corresponding action makes the transparent and avascular lens rounder?
Contraction of the ciliary muscle
What structure and corresponding action makes the lens flatter?
Relaxation of the ciliary muscle
How can you describe the inner and outer layers of the retina?
outer pigment layer and inner neural layer
Optic disc
optic disc: where the optic nerve enters; insensitive to light (there are NO rods or cones present here)
Macula lutea
macula lutea: a disc with the fovea centralis; most acute vision
(SO4LR6)3
All eye muscles are innervated by the oculomotor nerve CN III EXCEPT the superior oblique (trochlear nerve CN IV) and lateral rectus (abducens nerve CN VI)
Eye muscles: Elevators
Inferior oblique and superior rectus
Eye muscles: Depressors
Inferior rectus and superior oblique
Eye muscles: ADductors
Medial rectus, superior rectus and inferior rectus
Eye muscles: ABductors
Superior oblique, inferior oblique, and lateral rectus
What is the pathway for the motor innervation of the superior rectus and levator palpebrae superioris?
Cell body of LMN in Occulomotor complex (midbrain)–>cavernous sinus–>superior orbital fissure–>SUPERIOR division branches
What is the pathway for the motor innervation of the medial rectus, inferior rectus and inferior oblique muscles?
Cell body of LMN in Occulomotor complex (midbrain)–>cavernous sinus–>superior orbital fissure–>INFERIOR division branches
What is the pathway for the motor innervation of the superior oblique muscle?
CN IV-Cell body of LMN in Trochlear nucleus–>cavernous sinus–>superior orbital fissure–>superior oblique
What is the pathway for the motor innervation of the lateral rectus muscle?
CN VI-Cell body of LMN in abducens nucleus (midbrain)–>cavernous sinus–lateral rectus
What two arteries provide blood supply to the ethmoid air cells and nasal cavity?
Posterior and anterior ethmoid arteries
What blood vessel provides blood supply to the choroid layer?
short posterior ciliary arteries
What vessels provide the blood supply to the ciliary body and iris?
long posterior ciliary arteries
What structures are supplied by the ciliary arteries?
Sclera, choroid, ciliary body and iris
The superior opthalmic vein drains into the …
cavernous sinus
The inferior opthalmic vein drains into the…
pterygoid plexus and cavernous sinus
Both the superior opthalmic and inferior opthalmic veins anastamose with the …
facial vein
What provides general sensory innervation to the orbit?
CN V. Mainly opthalmic division VI and some maxillary division V2
What is the neural pathway for the lacrimal, frontal and nasociliary nerves?
Sensory cell bodies in trigeminal ganglion–>V1 branches from the ganglion in the cranial cavity–>cavernous sinus–>superior orbital fissure–>orbit–>branches into the sensory nerves
Lacrimal nerve (sensory innervation)
lateral upper eyelid, lacrimal gland and some conjunctiva
Frontal nerve (2 branches-sensory innervation)
Supraorbital AND supratrochlear nerves-upper eyelid, forehead and scalp
Nasociliary nerve (4 main branches-sensory innervation)
Long ciliary nerves (eyeball), posterior ethmoidal nerve (sphenoid sinus, ethmoid air cells and nasal cavity), anteior ethmoidal nerve (ethmoidal air cells and nasal cavity), infratrochlear nerve (medial upper eyelid and lacrimal sac)
What branch of the anterior ethmoidal nerve supplies general sensory innervation to the bridge of the nose?
External nasal branches
Which nerve provides general sensory innervation to the lower eyelid and the eyeball?
Inferior palpebral nerve
By definition, long ciliary nerves are…
general sensory nerves from V1
By definition, short ciliary nerves are…
post-ganglionic parasympathetic fibers from CN III
Parasympathetic innervation to the ciliary muscle and constrictor pupillae
Preganglionic cells are in the Edinger Westphal nucleus (midbrain)–>cavernous sinus–>superior orbital fissure–>pre-ganglionic fibers synapse in the ciliary ganglion–>postganglionic fibers are now called short ciliary nerves–>enter eyeball–>innervate ciliary muscles and constrictor pupillae muscles
Parasympathetic innervation to the lacrimal gland
Preganglionic cell bodies in superior salivatory nucleus (pons)–>internal acoustic meatus–>facial canal–>greater petrosal nerve branches in the facial canal–>greater petrosal nerve is joined by the deep petrosal nerve (sympathetic fibers) to form nerve of pterygoid canal–>pterygopalatine fossa–>pre-ganglionic fibers synapse with post-ganglionic fibers in pterygopalatine ganglion–>postganglionic fibers jump onto the zygomatic nerve of V2–>jump onto the lacrimal nerve of V1–>lacrimal gland
Sympathetic innervation pathway for dilator pupillae and superior tarsal muscle
Preganglionic fibers originate T1-L2–>enter chain–>ascend to superior cervical ganglia–>synapse–>postganglionic fibers hitchhike on the internal carotid artery–>opthalmic artery–>fibers then hithhike onto short or long ciliary nerves or muscular branches of III and go on to innervate the dilator pupillae and superior tarsal muscle.
Which reflex combines a sensory component of V and a motor component of VII?
Corneal reflex
Corneal reflex: Absent ipsilateral with normal contralateral response
Normal V with abnormal ipsilateral VII
Corneal reflex: Absent bilateral response
V abnormality OR bilateral VII abnormality
Corneal reflex: Absent contralateral response
Abnormal contralateral VII
