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Anatomy Exam 2 > The Orbit > Flashcards

The Orbit Flashcards

1
Q

Bones of the Orbit

A

Lacrimal, frontal, maxillary, palatine, zygomatic, ethmoid, sphenoid

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2
Q

Bounds of the orbit

A

Four walls: Superior wall, medial wall, floor (inferior wall), lateral wall. Apex and base

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3
Q

Superior wall of the Orbit

A

Almost horizontal. Also known as the roof; formed by the orbital part of the frontal (mainly) and sphenoid bones (lesser wings). Separates the orbit from the overlying anterior cranial fossa. Lacrimal fossa located in this region

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4
Q

Lacrimal fossa

A

located in the superolateral part of the orbital plate of frontal bone. The lacrimal gland is located here

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5
Q

Medial Wall of the orbit

A

Paper thin. Formed by the ethmoid (mainly), frontal, lacrimal and sphenoid bones. Contains the fossa for the lacrimal sac and nasolacrimal duct. Medial walls of the two orbits are parallel to each other. Anteriorly indented by the lacrimal groove and the fossa for lacrimal sac.

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6
Q

Floor of the orbit

A

Aka inferior wall. Formed by the maxilla (mainly), zygomatic and palatine bones Maxillary sinus is on the other side of the floor.

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7
Q

Lateral wall of the orbit

A

Thickest and strongest wall. Formed by the maxilla (mainly), zygomatic and palatine bones. Maxillary sinus is on the other side of the floor

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8
Q

Apex of the orbit

A

Located at the optic canal in the lesser wing of the sphenoid bone

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9
Q

Fracturing of orbits

A

Medial and inferior wall (floor) of orbit are very thin. Blowout fractures can result from indirect traumatic injury. All walls are thin and readily penetrated by a sharp object. Orbital margins usually remain intact

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10
Q

Orbital Tumors

A

Tumors might be located in the sinuses along the medial wall but can push into the orbit, pressing against the optic nerve. Tumors and bleeding can lead to protrusion of the eyeball: exophthalmos

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11
Q

Exophthalmos

A

Protrusion of the eyeball(s); can be resultant of orbital tumors and/or bleeding

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12
Q

Eyelids

A

Covered externally by skin and internally by conjunctiva (mucus membrane)

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13
Q

Tarsal Plates

A

Superior and inferior. connective tissue plates – form the skeleton of the lids

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14
Q

Tarsal Glands

A

embedded in the tarsal plates - secrete lipid material to lubricate edges of the lids

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15
Q

Ciliary Glands

A

large sebaceous glands of the eyelid

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16
Q

Orbicularis Oculi Palpebral Muscle

A

Innervated by facial nerve. Closes the eyelid.

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17
Q

Levator Palpebrae Superioris

A

Innervated by oculomotor nerve. Elevates the upper eyelid

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18
Q

Medial Palpebral Ligament

A

Origin and insertion of the orbicularis oculi muscle. Connects tarsal plates to medial margin of the orbit

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19
Q

Lacrimal apparatus

A

Orbital structures responsible for tear production and drainage. Consists of lacrimal gland, lacrimal ducts, lacrimal lake, lacrimal canaliculi, lacrimal sac, and nasolacrimal duct

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20
Q

Lacrimal gland and lacrimal ducts

A

Secrete the lacrimal fluid. Located in the superolateral part of the orbit (lacrimal fossa). Ducts 8-12 open in the superior conjunctival fornix. Lacrimal gland is stimulated by parasympathetic nerves of CNVII (Facial).

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21
Q

Lacrimal Lake

A

Collecting area of tears at the medial angle of the eye

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22
Q

Lacrimal Canaliculi

A

One for each eyelid. The lateral opening of the canaliculi are represented by the lacrimal papillae. Conveys tears from the lacrimal lake to the lacrimal sac

23
Q

Lacrimal Sac

A

Dilated upper end of the nasolacrimal duct. The other end of the canaliculi opens here.

24
Q

Nasolacrimal duct

A

Extends inferiorly into the nose. Opens at the inferior meatus of the nasal cavity

25
Q

Conjunctiva

A

Line the inside of the eyelide, cover the sclera (white portion of the eye). Inside covering of the eyelid (palpebral conjunctiva) and eyeball (bulbar conjunctiva).

26
Q

Palpebral Conjunctiva

A

Inside covering of the eyelid

27
Q

Bulbar conjunctiva

A

Outer covering of the eyeball

28
Q

Conjunctival fornix

A

Forms the junction between the bulbar and palpebral conjunctivas. It is loose and flexible, allowing the free movement of the lids and eyeball

29
Q

Superior conjunctival fornix

A

the space in the fold of the conjunctiva created by the reflection of the conjunctiva covering the eyeball and the lining of the upper lid

30
Q

Inferior conjunctival fornix

A

the space in the fold of conjunctiva created by the reflection of the conjunctiva covering the eyeball and the lining of the lower eyelid

31
Q

Extraocular muscles

A

AKA Extrinsic muscles. Move the superior eyelid and the eyeball. Recti muscles (Superior, inferior, medial, lateral), superior oblique, inferior oblique, levator palpebrae superioris.

32
Q

Describe the innervation of the extraoccular muscles

A

SO(IV) LR (IV). Rest (III). Superior Oblique CN IV (Trochlear), Lateral Rectus CNVI (Abducens), Rest CNIII (Oculomotor)

33
Q

Recti muscles

A

Originate from the common tendinous ring- fibrous structure originating from optic foramen and part of the superior orbital fissure. All four recti muscles attach to the sclera of the eyeball. Recti: lateral rectus(CNVI), medial rectus, superior rectus, inferior rectus

34
Q

Superior rectus

A

CNIII. Rotate pupils superiorly and medially

35
Q

Inferior rectus

A

CNIII. Rotate pupils inferiorly and medially

36
Q

Medial Rectus

A

CNIII. Rotate pupils medially

37
Q

Lateral Rectus

A

CNVI. Rotate pupils laterally.

38
Q

Nerves of the orbit

A

Optic Nerve, Opthalmic of CNV (CNV1), Oculomotor Nerve, Trochlear Nerve, Abducens Nerve, Autonomics

39
Q

Optic Nerve

A

Enters orbit via optic canal

40
Q

Opthalmic division of CNV

A

CNV1. First three terminal branches of opthalmic nerve enter orbit via superior orbital fissure. Supply sensory innervation to anterior orbit (lacrimal gland and eyelids), face, and scalp. Gives rise to frontal, lacrimal, and nasocilliary nerves.

41
Q

Frontal branch of CNV1

A

Largest branch of CNV1. Located superficial to levator palpebrae superioris muscle along roof of orbit. Travels anteriorly to give rise to two branches: supraorbital and supratrochlear

42
Q

Lacrimal Nerve

A

Smallest branch of CNV1. Enters the orbit through the superior orbital fissure and travels laterally superficial to lateral rectus muscle to reach lacrimal gland. Sensory nerve to lacrimal gland.

43
Q

Nasocillary Nerve

A

Supplies sensory branches to the eyeball via ciliary nerves. Some of the ciliary nerves pass through the ciliary ganglion. Nasociliary nerve continues along the medial wall of the orbit and gives rise to the following branches: Posterior ethmoidal, anterior ethmoidal, infratrochlear (terminal branch, sensory)

44
Q

Oculomotor Nerve

A

Enters through superior orbital fissure. Motor nerve to all muscles of orbit except Suprior Oblique (Trochler) and Lateral Rectus (Abducens).

45
Q

Trochlear Nerve

A

Enters orbit through superior orbital fissure. Motor nerve to superior oblique muscle.

46
Q

Abducens nerve

A

Enters orbit through superior orbital fissure. Motor nerve to lateral rectus muscle.

47
Q

Parasympathetic Autonomic Innervation of the Orbit

A

Preganglionic parasympathetic fibers for the smooth muscles of the eyeball (not the lacrimal gland) originate from the brainstem and enter the oculomotor nerve. Oculomotor nerve carries these preganglionic fibers into the orbit. Inside the orbit all preganglionic parasympathetic fibers leave CN III via its motor root. Motor root is a branch of CNIII: carries preganglionic fibers to the cilliary ganglion (Located in the orbit along the posterolateral side of the optic nerve). postganglionic fibers leave the ganglion via the short ciliary nerves (branches of CNV) and enter the eyeball. In the eyeball, the parasympathetic fibers supply the smooth muscles of the eyeball

48
Q

Cilliary Ganglia

A

Very small (size of pinhead). Contains cell bodies of postganglionic parasympathetic neurons; This is where the preganglionic fibers terminate and the postganglionic fibers begin

49
Q

Parasympathetic Autonomic Innervation of Lacrimal Gland

A

Branches of CNVII. Postganglionic fibers originate from the pterygopalatine ganglion and enter the orbit via the zygomatic branch of the maxillary nerve

50
Q

Sympathetic Innervation of the Orbit

A

Postganglionic sympathetic fibers from the superior cervical ganglion enter the orbit with the wall of blood vessels

51
Q

Blood vessels of Orbit

A

Opthalamic artery and veins

52
Q

Opthalamic artery

A

Enters the orbit through the optic canal and gives rise to the following branches: Supraorbital artery, supratrochlear artery, lacrimal artery, and central artery of retina

53
Q

Opthalamic veins

A

Venous drainage occurs via superior and inferior opthalamic veins. These veins pass through the superior orbital fissure and enter the cavernous sinus inside the skull

Anatomy Exam 2 (8 decks)

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