Chapter 3 - Orbita

Question 1

Orbital Volume

Answer 1

30cm2

Question 2

Orbit:

Entrance high

Answer 2

35 mm

Question 3

Orbit

Entrance width

Answer 3

40 mm

Question 4

Orbit

Medial wall length

Answer 4

45 mm

Question 5

Orbit

Distance from posterior globe to optic foramen

Answer 5

18 mm

Question 6

Orbit

Length of orbital segment of optic nerve

Answer 6

25-30 mm

Question 7

The orbital walls are composed of the following 7 bones:

Answer 7

• ethmoid
• frontal
  _ lacrimal
  _ maxillary
  _ palatine
  _ sphenoid
• Zygomatic

Question 8

Roof of the orbit is composed of:

Answer 8

1. The frontal bone

2. The lesser wing of the sphenoid

Question 9

Roof of the Orbit

Answer 9

• composed of the frontal bone and the lesser wing of the sphenoid
  
  • important landmarks: thelacrimal gland fossa,which contains the orbital lobe of the lacrimal gland; thefossa for the trochlea of the superior oblique tendon,located 5 mm behind the superior nasal orbital rim; and thesupraorbital notch,orforamen,which transmits the supraorbital vessels and branch of the frontal nerve
  • located adjacent to anterior cranial fossa and frontal sinus

Question 10

Lateral Wall of the Orbit

Answer 10

• composed of the zygomatic bone and the greater wing of the sphenoid; separated from the lesser wing portion of the orbital roof by the superior orbital fissure
  
  • important landmarks: thelateral orbital tubercle of Whitnall,with multiple attachments, including the lateral canthal tendon, the lateral horn of the levator aponeurosis, the check ligament of the lateral rectus, the Lockwood ligament (the suspensory ligament of the globe), and the Whitnall ligament; and thefrontozygomatic suture,located 1 cm above the tubercle
  • located adjacent to the middle cranial fossa and the temporal fossa
  • commonly extends anteriorly to the equator of the globe, helping to protect the posterior half of the eye while still allowing wide peripheral vision
  • is the thickest and strongest of the orbital walls

Question 11

Medial Wall of the Orbit

Answer 11

• composed of the ethmoid, lacrimal, maxillary, and sphenoid bones
  
  • important landmark: thefrontoethmoidal suture,marking the approximate level of the cribriform plate, the roof of the ethmoids, the floor of the anterior cranial fossa, and the entry of the anterior and posterior ethmoidal arteries into the orbit
  • located adjacent to the ethmoid and sphenoid sinuses and nasal cavity
  • medial wall of the optic canal forms the lateral wall of the sphenoid sinus

Question 12

The thinnest walls of the orbit are

Answer 12

thelamina papyracea,which covers the ethmoid sinuses along the medial wall, and themaxillary bone,particularly in its posteromedial portion. These are the bones most frequently fractured as a result of indirect, or blowout, fractures (see Chapter 6). Infections of the ethmoid sinuses may extend through the lamina papyracea to cause orbital cellulitis and proptosis.

Question 13

Floor of the Orbit

Answer 13

• composed of the maxillary, palatine, and zygomatic bones
  
  • forms the roof of the maxillary sinus; does not extend to the orbital apex but instead ends at the pterygopalatine fossa; hence, it is the shortest of the orbital walls
  • important landmarks: theinfraorbital grooveandinfraorbital canal,which transmit the infraorbital artery and the maxillary division of the trigeminal nerve

Question 14

Ethmoidal Foramina

Answer 14

The anterior and posterior ethmoidal arteries pass through the corresponding ethmoidal foramina in the medial orbital wall along the frontoethmoidal suture. These foramina provide a potential route of entry into the orbit for infections and neoplasms from the sinuses.

Question 15

Superior Orbital Fissure

Answer 15

The superior orbital fissure separates the greater and lesser wings of the sphenoid and transmits cranial nerves III, IV, and VI; the first (ophthalmic) division of cranial nerve (CN) V; and sympathetic nerve fibers. Most of the venous drainage from the orbit passes through this fissure by way of the superior ophthalmic vein to the cavernous sinus.

Question 16

Inferior Orbital Fissure

Answer 16

The inferior orbital fissure is bounded by the sphenoid, maxillary, and palatine bones and lies between the lateral orbital wall and the orbital floor. It transmits the second (maxillary) division of CN V, including the zygomatic nerve, and branches of the inferior ophthalmic vein leading to the pterygoid plexus. The infraorbital nerve, which is a branch of the maxillary nerve, leaves the skull through the foramen rotundum and travels through the pterygopalatine fossa to enter the orbit at the infraorbital groove. This fossa extends laterally to become the infratemporal fossa. The nerve travels anteriorly in the floor of the orbit through the infraorbital canal, emerging on the face of the maxilla 1 cm below the inferior orbital rim. The infraorbital nerve carries sensation from the lower eyelid, cheek, upper lip, upper teeth, and gingiva. Numbness in this distribution often accompanies blowout fractures of the orbital floor and typically improves with time.

Question 17

Apertures of the zygomatic bone

Answer 17

Zygomaticofacial and Zygomaticotemporal Canals
The zygomaticofacial canal and zygomaticotemporal canal transmit vessels and branches of the zygomatic nerve through the lateral orbital wall to the cheek and the temporal fossa, respectively.

Question 18

Optic Canal

Answer 18

The optic canal is 8–10 mm long and is located within the lesser wing of the sphenoid. This canal is separated from the superior orbital fissure by the bony optic strut. The optic nerve, ophthalmic artery, and sympathetic nerves pass through this canal. The orbital end of the canal is the optic foramen, which normally measures less than 6.5 mm in diameter in adults. Optic canal enlargement accompanies the expansion of the nerve, as seen with optic nerve gliomas. Blunt trauma may cause an optic canal fracture, hematoma at the orbital apex, or shearing of the nerve at the foramen, resulting in optic nerve damage.

Question 19

Nasolacrimal Canal

Answer 19

The nasolacrimal canal extends from the lacrimal sac fossa to the inferior meatus beneath the inferior turbinate in the nose. Through this canal passes the nasolacrimal duct, which is continuous from the lacrimal sac to the nasal mucosa (see Part III, Lacrimal System).

Question 20

superior orbital fissure

Answer 20

is located between the greater and lesser wings of the sphenoid bone and lies lateral to and partly above and below the optic foramen. It is approximately 22 mm long and is spanned by the common tendinous ring of the rectus muscles(annulus of Zinn).Above the ring, the superior orbital fissure transmits the following structures (Fig 1-3):
• lacrimal nerve of CN V1
• frontal nerve of CN V1
• CN IV (trochlear nerve)
• superior ophthalmic vein
Within the ring or between the 2 heads of the rectus muscle are the following:
• superior and inferior divisions of CN III (the oculomotor nerve)
• nasociliary branch of CN V1
• sympathetic roots of the ciliary ganglion
• CN VI (the abducens nerve)
The course of the inferior ophthalmic vein is variable, and it can travel within or below the ring as it exits the orbit.

Question 21

inferior orbital fissure

Answer 21

lies just below the superior fissure between the lateral wall and the floor of the orbit, providing access to the pterygopalatine and inferotemporal fossae. Therefore, it is close to the foramen rotundum and the pterygoid canal. The inferiororbital fissure transmits the infraorbital and zygomatic branches of CN V2, an orbital nerve from the pterygopalatine ganglion, and the inferior ophthalmic vein. The inferior ophthalmic vein connects with the pterygoid plexus before draining into the cavernous sinus.

Question 22

superior orbital fissure, nerves and veins that go through are:

Answer 22

lacrimal nerve of CN V1, frontal nerve of CN V1, CN IV (trochlear nerve), superior ophthalmic vein
Within the ring or between the 2 heads of the rectus muscle are the following: superior and inferior divisions of CN III (the oculomotor nerve), nasociliary branch of CN V1, sympathetic roots of the ciliary ganglion, CN VI (the abducens nerve)

Question 23

The inferiororbital fissure transmits:

Answer 23

the infraorbital and zygomatic branches of CN V2, an orbital nerve from the pterygopalatine ganglion, and the inferior ophthalmic vein. The inferior ophthalmic vein connects with the pterygoid plexus before draining into the cavernous sinus.

Question 24

The ciliary ganglion is located:

Answer 24

approximately 1 cm in front of the annulus of Zinn, on the lateral side of the ophthalmic artery between the optic nerve and the lateral rectus muscle

Question 25

The ciliary ganglion receives 3 roots:

Answer 25

1. A long sensory root arises from the nasociliary branch of CN V1. It is 10–12 mm long and contains sensory fibers from the cornea, the iris, and the ciliary body. 2. A short motor root arises from the inferior division of CN III, which also supplies the inferior oblique muscle. The fibers of the motor root synapse in the ganglion, and the postganglionic fibers carry parasympathetic axons to supply the iris sphincter. 3. A sympathetic root comes from the plexus around the internal carotid artery. It enters the orbit through the superior orbital fissure within the tendinous ring, passes through the ciliary ganglion without synapse, and innervates ocular blood vessels and the dilator muscles of the pupil.

Question 26

Ganglion ciliare. | A long sensory root arises from the nasociliary branch of CN V1. It is:

Answer 26

10–12 mm long and contains sensory fibers from the cornea, the iris, and the ciliary body.

Question 27

Ganglion ciliare. 2. A short motor root arises from the inferior division of CN III, which also supplies 1.) The fibers of the motor root synapse in the ganglion, and the postganglionic fibers carry 2.)

Answer 27

1. the inferior oblique muscle. | 2. parasympathetic axons to supply the iris sphincter.

Question 28

Ganglion ciliare. | 3. A sympathetic root comes from the plexus around the internal carotid artery. It enters the orbit through

Answer 28

the superior orbital fissure within the tendinous ring, passes through the ciliary ganglion without synapse, and innervates ocular blood vessels and the dilator muscles of the pupil.

Question 29

Branches of the Ciliary Ganglion Together, the nonsynapsing sympathetic fibers; the sensory fibers; and the myelinated, fast-conducting postganglionic parasympathetic fibers form the

Answer 29

short ciliary nerves.

Question 30

Two groups of short ciliary nerves arise from the ciliary ganglion. They travel on both sides of the optic nerve and, together with the long ciliary nerves, pierce the sclera around the optic nerve. Where do they go?

Answer 30

They pass anteriorly between the choroid and the sclera into the ciliary muscle, where they form a plexus that supplies the cornea, the ciliary body, and the iris.

Question 31

There are 7 extraocular muscles:

Answer 31

1. medial rectus 2. lateral rectus 3. superior rectus 4. inferior rectus 5. superior oblique 6. inferior oblique 7. levator palpebrae superioris

Question 32

The spiral of Tillaux is:

Answer 32

The medial rectus tendon is closest to the limbus, and the superior rectus tendon is farthest from it. By connecting the insertions of the tendons beginning with the medial rectus, then the inferior rectus, then the lateral rectus, and finally the superior rectus, a spinal is obtained.

Question 33

Rhinoorbitale Mukormykose | Präsentation:

Answer 33

langsame Entwicklung einer Gesichts- und periorbitalen Schwellung, Diplopie und Visusverlust

Question 34

Rhinoorbitale Mukormykose ist eine:

Answer 34

sehr seltene opportunistische Infektion, die durch Pilze der Familie Mucoraceae verusacht wird. Sie betrifft typischerweise Patienten mit diabetischer Ketoazidose oder Immunsuppression. Diese aggressive und potenziell tödliche Infektion wird durch die Inhalation von Sporen erworben, die zu einer Infektion des oberen Respirationstrakts führen. Die Infektion breitet sich anschließend kontinuierlich in die angrenzenden Sinus sowie in die Orbita und das Gehirn aus. Die Invasion der Blutgefäße durch die Hyphen führt zu einer okklusiven Vaskulitis mit einem ischämischen Infarkt der Orbitagewebe.

Question 35

Rhinoorbitale Mukormykose | Befunde:

Answer 35

- Ein ischämischer Infarkt, der eine septische Nekrose überlagert, ist für den schwarzen Schorf verantwortlich, der sich am Gaumen, an den Nasenmuscheln, am Nasenseptum, an der Haut und an den Lidern entwickeln kann. – Ophthalmoplegie – langsamere Progression als bei einer bakteriellen Orbitaphlegmone

Question 36

Rhinoorbitale Mukormykose | Komplikationen: 

Answer 36

retinale Gefäßverschlüsse, multiple Hirnnervenlähmungen und zerebrovaskuläre Verschlüsse