Anatomy Unit 24: Orbit

Front 1

Boundaries of Orbit

Back 1

Roof: Orbital plate of frontal bone, lesser wing of sphenoid
Floor: maxilla, zygomatic bone, and orbital process of palatine.
Medial: Frontal process of maxilla, lacrimal bone, orbital plate of ethmoid, body of sphenoid
Lateral: Greater wing of sphenoid and frontal process of zygomatic.

Front 2

7 Bones of orbit acronym

Back 2

Spenoid - seven
frontal - funny
lacrimal - little
zygomatic - zebras
palatine - play
maxilla - music
ethmoid - easily

Front 3

Contents of superior orbital fissure

Back 3

-occulomotor nerve (CN 3)
-trochlear nerve (CN 4)
-Ophthalmic division of trigeminal (V1)
-Abducens Nerve (CN 6)
-Autonomic post ganglionic fibers on other nerves
-Superior Ophthalmic Vein

Front 4

Location of superior orbital fissure

Back 4

Between greater and lesser wing of sphenoid.

Front 5

Contents of inferior orbital fissure

Back 5

-Infraorbital Nerve (V2)
-Infraorbital Vessels
-Communication between inferior ophthalmic veins and pterygoid plexus of veins
-Infraorbital and zygomatic branches of V2 carry autonomic post ganglionic fibers

Front 6

Trochlear Fossa

Back 6

May just be a ridge not a fossa. Is the pivot point for the superior oblique muscle.

Front 7

Infraorbital Foramen

Back 7

Associated with canal and groove of same name. Nerves and blood vessels of the same name pass through it.

Front 8

Fossa for lacrimal Sac

Back 8

Between anterior and posterior Lacrimal crests

Front 9

Layers of Eyelid

Back 9

-Skin
-Subcutaneous tissue
-muscle layer
-tarsus plate
-conjunctiva

Front 10

Palpebra

Back 10

Eyelid

Front 11

Skeleton of Eyelid

Back 11

Acts as a partition between eyelid. Consists of Tarsal plates, medial and lateral palpebral ligaments, and orbital septum

Front 12

Medial and Lateral Palpebral ligaments

Back 12

Attach Tarsal plates to orbital bone.

Front 13

Orbital Septum

Back 13

Attaches to orbital rim, tarsal plates, and palpebral ligaments

Front 14

Tarsal Glands

Back 14

Brisles on the comb (Tarsal plate). Secrete oily liquid. Can get infected.

Front 15

Canthus

Back 15

Medial or lateral angles of palpebral fissure

Front 16

Lacrimal Lake

Back 16

Space at medial angle of palpebral fissure for tear accumulation.

Front 17

Conjunctiva

Back 17

When skin of eyelids reaches palpebral fissure, wraps around and coats eyelid from inside. Goes from epidermis to epithelial. 2 kinds:
Palpebral conjunctiva - coats inside of eyelid.
Bulbar conjunctiva - coats globe. Is continuation of palpebral after the conjunctival fornix

Front 18

Conjunctival Fornix

Back 18

Where conjunctiva leaves the eyelid, folds, and coats globe. Transition point from palpebral conjunctiva to bulbar conjunctiva.

Front 19

Tarsal Plate

Back 19

Acts as skeleton for eyelid allowing it to keep its shape. Flexible dense connective tissue.

Front 20

Fascial Sheaths of Eyeball

Back 20

Bulbar fascia
suspensory ligament - thickening of bulbar fascia under eyeball
Check ligaments - Expansion of Muscle sheaths to orbital wall

Front 21

Superior Rectus Muscle

Back 21

Origin: From common tendinous ring at apex.
Action: Elevates and Adducts Pupil
Innervation: Superior division of Occulomotor Nerve (CN 3)

Front 22

Inferior Rectus Muscle

Back 22

Origin: From common tendinous ring at apex.
Action: Depresses and Adducts Pupil
Innervation: Inferior division of Occulomotor Nerve (CN 3)

Front 23

Lateral Rectus Muscle

Back 23

Origin: From common tendinous ring at apex.
Action: Abducts pupil
Innervation: Abducens Nerve (CN 6)

Front 24

Medial Rectus Muscle

Back 24

Origin: Common tendinous ring at apex
Action: Adducts Pupil
Innervation: Inferior division of occulomotor nerve

Front 25

Superior Oblique Muscle

Back 25

Origin: Above and medial to tedonous ring.
Inserts: On sclera, passes through trochlear sling.
Action: Depress and Abduct pupil
Innervation: Trochlear Nerve (CN 4)

Front 26

Inferior Oblique Muscle

Back 26

Origin: Anterior, Inferior, and medial in orbit
Insert: Lateral aspect
Action: Abducts and Elevates Pupil
Innervation: Inferior division of occulomotor nerve (CN 3)

Front 27

Levator Palpebrae Superioris Muscle

Back 27

Origin: Above common tendinous ring
Inserts: Superior Tarsal Plate. Also attached to tarsal plate via superior tarsal muscle (smooth muscle)
Action: Elevates upper eyelid
Innervation: Superior division of occulomotor nerve (CN 3)

Front 28

Superior Tarsal Muscle

Back 28

Smooth muscle which connects levator palpebrae superioris to the tarsal plate. Is innervated by sympathetic nerves.

Front 29

Partial v.s. Full ptosis

Back 29

Partial ptosis - partial drooping of eyelid. Caused by loss of sympathetic innervation to superior tarsal muscle.
Full ptosis - Full drooping of upper eyelid. Caused by loss of occulomotor innervation to levator palpebrae superioris

Front 30

Central Artery of Retina

Back 30

Given off by ophthalimic artery when inferior to the optic nerve. Pierces optic nerve. Is only blood supply to retina therefore disruption = blindness. Runs with a vein of the same name.

Front 31

Superior Ophthalmic Vein

Back 31

Receives from supraorbital, facial, and inferior orbital veins and drains into the cavernous sinus. (No valves, therefore, bacteria can spread this way)

Front 32

Inferior Ophthalmic Vein

Back 32

Receives from infraorbital vein and from the pterygoid plexus of veins and drains into superior ophthalmic vein.

Front 33

Lacrimal Gland

Back 33

Divided into 2 parts by levator palpebrae superioris. Lacrimal duct drains gland into superior fornix. Stimulated by fibers from pterygopalatine ganglion which come via facial nerve.

Front 34

Lacrimal Puncta

Back 34

Hole in lacrimal papilla leading into lacrimal canaliculi.

Front 35

Acronym for occular muscle innervation

Back 35

LR6 SO4 Everything else by 3

Front 36

Lacrimal Canaliculi

Back 36

Small Canal entering into lacrimal sac

Front 37

Lacrimal Sac

Back 37

Upper expanded end of nasolacrimal duct where tears drain.

Front 38

Nasolacrimal duct

Back 38

Drains tears from lacrimal sac through inferior meatus of nasal cavity.

Front 39

Horners syndrome

Back 39

Sympathetics to head interrupted. Get a small pupil.

Front 40

Optic Nerve

Back 40

(CN 2) Special sensory for sight. From back of eyeball through optic foramen. Enclosed in a meningeal sheath; within sheath is central artery and vein of retina.

Front 41

Occulomotor Nerve

Back 41

Motor and parasympa. nerve.Enters orbit through orbital fissure and separates into superior and inferior divisions. Innervates most of occulomotor muscles. Also sends EGP fibers to cilliary ganglion.

Front 42

Superior division of occulomotor nerve

Back 42

(CN3)Innervates superior rectus and levator palpebrae superioris.

Front 43

Inferior division of occulomotor nerve

Back 43

(CN 3)Innervates medial rectus, inferior rectus, and inferior oblique muscles. Sends EGP to cilliary ganglion.

Front 44

Long Cilliary Nerve

Back 44

Branch off nasocilliary nerve (V1). Contains sensory fibers for orbit. Also has OGS from internal carotid plexus which dilate pupil.

Front 45

Short Ciliary Nerve

Back 45

Comes from cilliary ganglion. Receives sensory nerves from nasocilliary nerve, parasympathetic innervation from inferior branch of occulomotor, and sympathetic innervation (from somewhere). Does sensory for globe, innervates pupil, and is important for corneal reflex.

Front 46

Trochlear Nerve

Back 46

(CN 4) Motor. Enters obit through superior orbital fissue, innervates superior oblique muscle

Front 47

Opthalmic Nerve

Back 47

(V1) Sensory. Has 3 branches: Lacrimal, Frontal, and Nasocilliary.

Front 48

Lacrmial Nerve

Back 48

Branch of V1. Enters orbit through superior orbital fissure. Receives OGP from zygomatic nerve for lacrimal gland. Innervates lacrimal gland. Sensory to skin of upper eyelid.

Front 49

Frontal Nerve

Back 49

Largest branch of V1. Enters orbit through superior orbital fissure. Divides into supraorbital and supratrochlear nerves to supply skin.

Front 50

Nasocilliary Nerve

Back 50

Branch of V1. Enters orbit through superior orbital fissure passing through common tendinous ring. Gives off long cilliary nerve. Sends sensory fibers to eye via short and long ciliray nerves. Terminal branches are posterior ethmoidal, anterior ethmoidal, and infratrochlear nerve.

Front 51

Abducens Nerve

Back 51

(CN 6) Motor. Enters superior orbital fissure through common tendinous ring. Innervates lateral rectus muscle.

Front 52

Things which pass through common tendinous ring.

Back 52

-Occulomotor nerve (CN 3)
-Nasocilliary Nerve (V1)
-Abducens nerve (V6)

Front 53

Things which pass/originate near common tendonous ring

Back 53

-Superior oblique muscle (superior and medial)
-Levator palpebrae superioris (Superior)
-Trochlear Nerve (Outside)
-Lacrimal Nerve (Outside)
-Frontal Nerve (Outside)