Oct18 M3-Anatomy_Orbit and Nose_Notes

Question 1

(dnm) intraocular mm fct

Answer 1

constrict or dilate pupil + change shape of lens

Question 2

orbit charact

Answer 2

• cone shaped
• triangle in the back
• wall in between 2 orbits

Question 3

other cavities in face

Answer 3

• paranasal sinuses (at least 4 of them, 2 on each side. 1 medial sup to orbit and 1 lat inf to orbit). are little pockets). open in the nasal cavities
• 2 nasal cavities

Question 4

coronal cut of orbit charact

Answer 4

• cavity on top = cranial cavity
• midline plate = cribriform plate where olfactory n. sits
• orbital fissure in the back
• optic canal = small hole medial to orbital fissure where optic n passes

Question 5

charact of bone around orbit

Answer 5

• diff thicknesses all around
• floor = thin layer of bone (bc pocket of empty bone (air circulating) underneath it, called the maxillary sinus). easily breakable bone, thin
• roof = thicker bc of thick frontal bone. so thick you have small cavities developing above orbit, called frontal sinuses

Question 6

lobotomy done how

Answer 6

remove part of frontal lobe for behavioral tx by going through orbit, breaking roof and reaching frontal lobe of brain

Question 7

orbit content

Answer 7

• lot of fat (70%)
• eyeball
• optic n. connecting to eyeball in the back
• extraocular muscles (levator palpebrae superioris m. for upper eyelid elevation + 6 mm for moving eyeball)

Question 8

extraocular muscles moving the eyeball

Answer 8

• sup rectus = elevate
• inf rectus = depress
• lat rectus = abduct eyeball (move lat)
• medial rectus = adduct
• inf oblique (start on medial wall and insert lat inf, coming from underneath medially)
• sup oblique (start on medial wall and insert lat sup)

Question 9

fct of inf oblique m.

Answer 9

• when looking straight, rotate eyeball laterally (counterclockwise) if the head tilts to maintain the visual field. called EVERSION (lat rotation)
• when eye adducted, elevate it by doing the eversion (so can look medial up)

Question 10

fct of sup oblique

Answer 10

• like inf oblique when looking straight, but turning clockwise. called INVERSION (medial rotation). stroke involving this m = pat comes in with head tilted
• when eye adducted, depress it by doing the inversion

Question 11

sup oblique m. trajectory

Answer 11

• comes from medial wall of orbit
• passes in trochlea (piece of bone, cartilage)
• one muscle belly before trochlea and one after
• 2nd ones does the inversion
• insert on lat side off eyeball
• supplied by trochlear n.

Question 12

how to test fct of eye muscles

Answer 12

H test. move fingers in a H shape in front of pt eyes. each direction = specific mm involved

Question 13

orientations of muscles and their origin in the orbit (what explains special fcts of sup oblique and inf oblique mm)

Answer 13

• the orbit is not perfectly AP and rather goes posterior = medial to anterior = lateral
• the eyeball axis however is perfectly AP
• bc of this diff, the muscles don’t come from back of eyeball but from medial wall of orbit

Question 14

look up lat = what muscles

Answer 14

• lat rectus

- sup rectus

Question 15

look down lat = what muscles

Answer 15

• lat rectus

- inf rectus

Question 16

look up medial = what mm

Answer 16

• medial rectus

- inf oblique (because sup rectus is not aligned with AP axis of eyeball anymore but inf oblique now is)

Question 17

look down medial = what mm

Answer 17

• medial rectus
• sup oblique (same reason. inf rectus not aligned with AP axis of eyeball anymore but sup oblique now is bc of its 7 shape bc of trochlea)

Question 18

CNs moving the eyeball

Answer 18

III, IV and VI

Question 19

IV (trochlear n) to what m

Answer 19

superior oblique

-short trochlear n. medially directly diving in sup oblique

Question 20

VI (abducens) to what m

Answer 20

lateral rectus (abducens n. is the name bc lateral rectus abducts the eye)
-small n. on surface of lat rectus

Question 21

III to what m

Answer 21

all others

• medial rectus
• inf rectus
• sup rectus
• inf oblique
• between sup rectus (inf) and levator papebrae superioris (sup) in middle of orbit*

Question 22

branches of V1 relating to the orbit

Answer 22

note: V1 and V2 are mainly sensory. V3 is motor
- lacrimal nerve (branch of V1) = lat wall, over lat rectus, to lacrimal gland (so near abducens n.)(sensation of gland fct + SS and PSS inn to control it)
- frontal nerve (branch of V1) = midline of orbit, sup to all mm. splits in ant part of orbit
- supraorbital n. (branch) of frontal nerve (V1 branch) more laterally: for surface of eyeball + skin of forehead
- supratrochlear n. (branch) of frontal n. (V1 branch) more medial: inn. space between two eyebrows

Question 23

summary of nn in orbit

Answer 23

medial to lat

• trochlear n. (CN IV) to sup oblique
• supratrochlear n. (branch of frontal n., branch of V1)
• frontal n.
• supraorbital n. (branch of frontal n., branch of V1)
• oculomotor n. (CN III) to 4 other extraocular mm
• abducens n. to lat rectus
• lacrimal n. (branch of V1) to lacrimal gland

Question 24

how to determine what the problem is if notice that one eye is deviated when pt looks straight

Answer 24

deviated eye is bc of unopposed action of a muscle. so problem in the opposite muscle

Question 25

one eye looking straight + other deviated medially dx

Answer 25

abducent nerve palsy | -disabled lateral rectus (unopposed adduction)

Question 26

one eye looking straight + other deviated medially up dx

Answer 26

trochlear n. palsy | -disabled sup oblique m. (unopposed inf oblique eversion)

Question 27

one eye looking straight + other deviated lat down dx

Answer 27

complete oculomotor palsy - sup rectus, inf rectus, medial rectus and inf oblique disabled - unopposed lat rectus and sup oblique

Question 28

lacrimal apparatus

Answer 28

- lacrimal gland superolat (for lubrication over all conjunctiva = epith of eyeball) in the eye. produces tears then drained in system of ducts - canaliculi for sup and inf eyelides (medially in orbit) - lacrimal sac (medially between orbit and nose) travels in bone to the nose (nasal cavity) - drains in nose * no valves in the lacrimal apparatus*

Question 29

problem related to no valves in lacrimal apparatus

Answer 29

fluid can go back up, high infection risk

Question 30

anterior and nasal apertures def

Answer 30

- opening of nostrils in the front (can collapse) | - opening of nasal cavity in the back (nasal CHOANAE) into the nasopharynx (can not collapse bc formed by bone)

Question 31

why useful that nasopharynx connects to mouth and nasal cavity?

Answer 31

can put mirror in back of mouth and look at nasal cavity from the back, check for obstruction, infection

Question 32

name of chin bone

Answer 32

maxilla (top of upper teeth medially, the palate of the mouth) -palate separates nasal cavity from oral cavity

Question 33

gap in maxilla where air can circulate

Answer 33

- maxillary sinus - bacteria can accum in these sinuses when we breathe - the ethmoid bone and the inferior nasal concha are 2 plates of BONE covering the nasal cavity from the maxillary sinus

Question 34

diff between the 3 nasal concha

Answer 34

- sup and middle nasal concha are plates coming off the ethmoid bone - the inferior nasal concha is a separate bone by itself * ALL 3 COVER OPENING of nasal cavity into maxillary sinus*

Question 35

concha physiology

Answer 35

- create little air spaces for air circulation so also called nasal turbinates (bc turbulence to create warm ir from contact with blood vessels and epith on concha) - epith of nasal cavity (covering concha) can get inflamed = stuffed nose, takes too much space, hard time to breathe bc nasal cavity is small (packed with bony processes and epith)

Question 36

2 fcts of nasal conchae

Answer 36

- separate nasal cavity and maxillary sinus | - warm and humidify inhaled air

Question 37

paranasal sinuses other than maxillary sinus (below eyes, lat to bottom nose)

Answer 37

- frontal sinuses (pockets in frontal bone at roof of orbit medially) - ethmoid cells (little cavities inside ethmoid bone). medial to eyes, lat to top nose - sphenoidal sinus (big cavity under cav sinus) * ALL COMM WITH NASAL CAVITY* * all these cavities grow with age so infection becomes more likely*

Question 38

nasal septum and palatine bones def

Answer 38

- nasal septum = midline sep of 2 nasal cavities | - palatine bones = bone of palate. maxillary sinus above it. dentists are first to see maxillary sinus infection

Question 39

where is the opening of sphenoidal sinus into nasal cavity

Answer 39

sup to superior concha

Question 40

what openings are underneath the middle concha

Answer 40

- frontal sinus opening - maxillary sinus opening - ethmoidal bullae (openings of ethmoidal cells, small holes) * so most openings underneath the middle concha*

Question 41

what is the semilunar hiatus

Answer 41

little groove underneath the middle concha (so relates to maxillary sinus, frontal sinus and ethmoidal bullae) where frontal sinus opens into maxillary sinus

Question 42

how surgery for pit tumor is done using the paranasal sinuses

Answer 42

- pit gland sits sup to sphenoidal sinus - can access this sinus from the nose - break posterior wall of sphenoidal sinus to access pituitary

Question 43

clinical relevance of paranasal sinuses

Answer 43

infections

Question 44

CT image with opacity in maxillary sinus, no prob of nasolacrimal duct, nasal cavity not obstructed, no fracture or bone damage: dx

Answer 44

infection of maxillary sinus