NBME 21 Inferior rectus and inferior oblique (NBME Answers)

NBME 21 Answers

nbme21/Block 2/Question#34 (reveal difficulty score)
A 28-year-old man is brought to the emergency ...
Inferior rectus and inferior oblique 🔍 / 📺 / 🌳
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+25
submitted by ∗seagull(1790),

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+16
submitted by ∗dr_jan_itor(81),

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otOinp A si the yoln ntoopi ehrew hotb seluscm aer artp of eht broilat Aof o.sllr,o teh satl enenesct in het itoquesn tsem si a oaltt meryofid fo thwa eno loudw xtecpe the ensqtiou ot be si.nkag It is nto kigasn rof uoy to messua atht sehte escmusl aevh nbee evrd,ees r,plaazyed or endrdere dlfaci. tI is gasnik uoy to sumsae ttah tehy vhea beeocm "epe"nartdp if eth elmusc is rpntea,dep htne ti ncntao wlalo the eye ot vmeo iotn hrwateve otpsoiin ti duwlo be in wneh het mucsle is ta tis elethenngd s.oonipti oS in itsh es,ca It si teh eironfri ecruts engib reappndte ni a atcifluynonl ntsroedeh niosoitp taht si nteeirpvgn udrawp .aegz

cjdinurdreamz im confused...doesnt the IR make the eye look down so if its trapped then why is upward gaze affected and not downward? +

nutmeg_liver @cjdinurdreamz it does make your eye look down, so since it's trapped in a functionally shorter position you're trapped looking down, not up. +4

+4
submitted by ∗soph(80),

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sti bc tihs ear teh only 2 culsems no het broital olfro lg eoog italobr rlofo csueslm ni lgogeo imea gsuec.&Eh=gmacO./gohN?lemroisgOPFwRL#c/=os+t=ilh/qmmwrpws:bbaito:arNstMu1eNlcstc

+4
submitted by ∗burak(64),

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taOlbri oflro c:urraetf

1- alrobntrIiaf eervn nij:ryu ubsmNsen nda eatsepshair fo eht perup c,kehe purpe pli, uerpp givagni.

2- nnetEmtapr fo teh iifernro ctresu emul:sc idaepIrm udpwra zgae

3- psiolotsEhmna

-4 gCuinols fo imylaarlx uniss: rpaToder nigs

minion7 if IR muscle is affected it is impaired downward gaze!!! +

makinallkindzofgainz @minion7, If the Inferior Rectus muscle is impaired (e.g. nerve dysfunction), then yes, downward gaze would be affected. However, the question states that there is ENTRAPMENT of muscles. Trapping the inferior rectus muscle essentially locks the eye into a downward gaze, therefore impairing upward gaze, as the inferior rectus muscle is essentially trapped in contraction. +5

+2
submitted by ∗sympathetikey(1535),

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ifrrnIoe elquoib = lsehp ouy loko pu a&;pm in.

,Aols teyh dsia oflro of eth ibto,r so it kames sesen atht hte neiofirr muselsc would da.gdmea

sahusema I know you're right. I was just so uncomfortable picking an answer with "inferior rectus" because damage to the inferior rectus does nothing to explain the clinical findings of impaired upward gaze. Unless the muscle is physically stuck and can't relax or something +7

emmy2k21 Agreed. Why would a dysfunctional inferior rectus contribute to impaired upward gaze??? I eliminated that answer choice and got it wrong :( +2

dr_jan_itor in the last sentence it asks you to assume an "entrapment", so it is actually the inferior rectus which is the cause of the upward gaze palsy. The entrapped muscle is functionally trapped in it's shortened position, thereby not allowing the orbit to gaze upward. +16

chandlerbas bam! dr_jan_itor just cleaned up that confusion +2

weirdmed51 Why inferior oblique then? Doesn’t IO helps to look up ? +1

freemanpeng May be IR is stronger than IO in downward gaze? +

+0
submitted by ∗blah_blah(1),

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rnIefior ueiolbq nda rirIonef ctuers melucs ear hbot ni hte brtolai ofolr. antmetnErp of teesh cssmuel will tno owlla thsee idiviulnda uesmlsc to od ihtre f.ounicnt

RI = eey cnntao olok OIwdno = eye ncnota oklo pu

+0
submitted by ∗freemanpeng(1),

Can anyone explain what "diplopia" implies? I got sutck by"these clinical findings" (thinking upward gaze+ diplopia....) Or is "Diplopia" just a unspecific word in exam??

-1
submitted by ∗niboonsh(394),

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heT ielsubqo od eth spoepoit aocnti fo htier nema. renifoIr iebqolu svoem teh eey UP dan OTU tooixte,n(r ta,leevnio c)BnodAtiu. nSiec eht ieuontsq assy htat teerh is a ufarcert ngoniivvl the oltriba frloo, ttah yliltoutcaama ulsre uto D midl(ae csture nda rfroiien ubq,ei)lo ialgevn eth oyln lcoagli werasn ot be the ifirreon cuetsr nda eirfrion qboeuil. l.pcW.?/tckKv/uyetIshIwwwtWmbW/uowEaoDth:=H

aishu007 hi, but inferior oblique moves up and in and not out +

d_holles https://www.youtube.com/watch?v=3J2UZiLVZKA In case ppl need a refresher +