Topic 1: Anatomical Planes & Orbit

Question 1

State the anatomical planes

Answer 1

sagittal, horizontal, coronal

Question 2

explain sagittal plane

Answer 2

divides structure into medial and lateral parts

Question 3

explain horizontal plane

Answer 3

divides the structure into superior and inferior parts

Question 4

explain coronal plane

Answer 4

divides the structure into anterior and posterior parts

Question 5

outline the orbital walls

Answer 5

roof/superior (concave), medial (very thin), lateral (thickest), floor/inferior (thinnest)

Question 6

explain roof of orbit

Answer 6

• concave
• bones: frontal, (lesser wing) sphenoid
• contains irregularity: optic foramen

Question 7

Explain medial wall

Answer 7

• very thin
• bones: ethmoid, lacrimal, maxillary, small part of sphenoid
• contains lacrimal fossa

Question 8

exolain lateral wall

Answer 8

• thickest
• bones: zygomatic, (greater wing) sphenoid
• separated from roof by superior orbital fissure

Question 9

explain floor of orbit

Answer 9

• thinnest
• most prone to blow out fracture
• bones: palatine, maxillary, zygomatic
• only wall not containing sphenoid

Question 10

explain periorbita

Answer 10

layer of tissue lining orbital walls

Question 11

explain orbital septum

Answer 11

Anterior boundary of the orbit, prevents facial infection from spreading into orbit -> infection from orbit can easily spread to brain

Question 12

explain Tennon’s capsule

Answer 12

AKA bulbar fascia thin membrane that lines the eyeball/covering sclera - except cornea and optic nerve region

Question 13

explain orbital fascia

Answer 13

sheets of connective tissue

line & support the structures within the orbit

allow for easy eye rotation

Question 14

Which anatomical planes have similar cross sections?

Answer 14

Horizontal and sagittal. They are both cut from the cornea to the back of the eyeball (behind retina), but optic nerve only seen closer to nose

Question 15

Explain ‘the equator’ etc of the eyeball

Answer 15

equator - cuts across half of eyeball

axial length - from midpoint of front eyeball (anterior pole) to midpoint of back eyeball (posterior pole)

Question 16

What geometric shape is the orbit similar to,

Answer 16

pyramid - square opening, four walls, apex

Question 17

explain optic foramen

Answer 17

1) optic nerve exits (to brain)
2) ophthalmic arteries enter (from heart)
3) in front is the annulus of zinn - origin of recti muscles (@ apex)