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NBME 22 Answers

nbme22/Block 2/Question#11 (56.2 difficulty score)
A 52-year-old man comes to the physician ...
Sensation from the anterior surface of the scrotum🔍
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 +9  upvote downvote
submitted by d_holles(139),
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I gto itsh eno iav pesocrs of nmileiin.tao oNt sure how uoy ear sopuedps ot brmmeeer all taht .htsi




From KenHub.com

  • Lumbar plexus
  • Genitofemoral nerve --> Genital branch ==> ANTEROLATEAL surface of scrotum
  • Ilioinguinal nerve --> Anterior scrotal nerve ==> ANTERIOR surface of scrotum
  • Sacral plexus
  • Pudendal nerve --> Posterior scrotal nerve ==> POSTERIOR surface of scrotum
  • Posterior cutaneous nerve of the thigh --> Perineal branches ==> INFERIOR surface of the scrotum

https://www.kenhub.com/en/atlas/anterior-scrotal-branch-of-ilioinguinal-nerve




 +4  upvote downvote
submitted by meningitis(412),
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cauAlt,ly I rtccore e:ymslf I eoklod orcsel nad hte etnoiG eolfmra sha an etaenrlx amSitrpec brhnca and a uaounnlbgiimL nr.chba I tgtohhu it was teh ieaolroetfmnG enevr eubacse eth atglein abnhcr sepssa otghruh teh peed anlnugii ingr, nrtese teh nanliuig al,can egos to cstrimaep rdoc dna puiselsp het cmtrsraee dna scorlta inks.

eersH eht ieg:ma irisurh44aGtemgaepiniow.ctd//8ipomn/:2ee.gpk//iw./akpyoadod/lms

etcorrC me if I ma gnwor pls.eea

gh889  I think you're right, FA2019 pp444 even states that sensory to the scrotum is via the Genitofemoral nerve +3  



 +4  upvote downvote
submitted by hello(250),
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Teh Q is gdrbcisien hte aloneitoermgf enver, ihcwh nrus on the ralenetx csfearu fo eth tmcrieasp dorc ta eth esailipfcur nlugniai inrg

Tihs Q is NOT ferrnreig to lliiunigioan ervne -- teh gialiulinoni reven itsex HURGOTH eth sifcilaepur nanguili alacn erewsha iths Q si insagk oatbu a vener ttah is ERTLNXAE to eht ieucfipslar uiinngal acl.na

eeS i/vtwgnelaaergach/e/p/jdecnopti.ti/ekcmosf..gwnircpudaai:wnst.f

trump2020  This is incorrect. You have it backwards. https://en.wikipedia.org/wiki/Spermatic_cord +2  
medjay7  Actually I think @hello is right. First, because that's the only way this shitty wording question makes sense, second cuz it says "that lies on the EXTERNAL SURFACE" that means outside of the spermatic cord, and the genital branch of GF nerve actually does: The genital branch of the genitofemoral nerve enters the inguinal canal via the deep inguinal ring. (https://www.ncbi.nlm.nih.gov/books/NBK430733/), and then exits to innervate the anterior and superior scrotal skin (also the cremaster muscle). +  
medjay7  CORRECTION: Nevermind, everything I said is wrong. I hate this question +  



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I ebevile r'yehte refrngrie to iomcroepssn fo hrencbsa fo het iaiulgnnoIli veNer (bssypiol teh oneirAtr toalSrc vNseer.

c:urSoe egakredk/oeci:soA/tiit_irttienrhs/_wnirr.wvpalspe/.on

armymed88  Ilioingual covers part of the medial thigh, base of penis and anterior scrotum Posterior scrotal nerves are a branch of pudendal and cover said area Doral nerves cover the dorsum of the penis which are also from the pudendal +1  
meningitis  I thought it was the Genitofemoral nerve because the genital branch supplies the cremaster and scrotal skin, but I looked it up and: The genital branch passes through the *deep inguinal ring* and enters the inguinal canal; also, Ilioinguinal wraps around the spermatic cord just like the question stem says. +1  
jean_young2019  "The structures which pass through the canals differ between males and females: in males: the spermatic cord[6] and its coverings + the ilioinguinal nerve." from wiki "Inguinal canal", which means the ilioinguinal nerve lies on the external surface of spermatic cord. https://en.wikipedia.org/wiki/Inguinal_canal The contents of spermatic cord includes, "nerve to cremaster (genital branch of the genitofemoral nerve) and testicular nerves (sympathetic nerves). It is worth noting that the ilio-inguinal nerve is not actually located inside the spermatic cord, but runs along the outside of it, in the inguinal canal." from wiki spermatic cord. https://en.wikipedia.org/wiki/Spermatic_cord +1  



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I hintk isht pceturi lixeaspn it :ewll

aiet.eiao/sc.wo/ldhgngcpwat/g.imjfrnat.tpi/aue:ek/crwnpndifcvse

hello  Adding to this... The Q is describing the GENIOFEMORAL nerve, which runs EXTERNAL TO of spermatic cord at the superficial inguinal ring This Q is NOT referring to ilioinguinal nerve, which exits THROUGH the superficial inguinal canal +  



 +2  upvote downvote
submitted by rainlad(20),

The other answer choices:

motor innervation to the bulbocavernosus muscle = deep/muscular branch of the perineal nerve, which is branch of the pudendal nerve

motor innervation to the lower portion of the rectus abdominis muscle = thoraco-abdominal nerves, which are continuations of the T7-T11 intercostal nerves

sensation from the dorsal surface of the penis = dorsal nerve of the penis, which is the deepest division of the pudendal nerve




 +2  upvote downvote
submitted by amd(2),

It is the ILIOINGUINALguys stop misleading ppl! https://www.openanesthesia.org/aba_ilioinguinal_anatomy/




 +1  upvote downvote
submitted by kevin(3),

Just to clarify all the comments.

  • (B) Rectus innervation would not be as deep as the spermatic cord (thoracoabdominal/intercostal nerves)

  • (A) & (D) are both pudendal nerve, I think it's reasonable to exclude both as an answer choice as such

  • (C) Process of elimination. Sure, we can nitpick if it's genitofemoral or ilioinguinal but I think that's all we're being tested on here




after rabbit-holing this one for a bit.... this is the photo that demonstrates it best (to me, anyway). must be ilioinguinal n.

enjoy

https://d1yboe6750e2cu.cloudfront.net/i/5e43dd40330f1cd702313cf56b29b8b3f793b00b




 +0  upvote downvote
submitted by diabetes(15),

The pampiniform plexus, testicular artery, cremasteric artery, artery of the ductus deferens, lymphatic vessels, testicular sympathetic nerves, and ductus deferens all run deep to the internal spermatic fascia. The ilioinguinal nerve runs on the superficial surface of the external spermatic fascia The ilioinguinal nerve is a sensory nerve that innervates the skin over the groin region, the medial aspect of the thigh, the upper part of the scrotum and the penile root. It is normally encountered during open repair of inguinal hernia.




 -1  upvote downvote
submitted by lovely(0),

It appears that both the genitofemoral nerve (genital branch) and the ilioinguinal nerve both are external to the spermatic cord and at the superficial inquinal canal. Depending on location of the genitofermal nerve makes a difference for what it innervates. It appears that the genitofemoral nerve (genital branch) innervates the lateral anterior surface of the srotum, while the ilioinguinal nerve innervates the anterior surface of the scrotum.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5503924/

Google also says that the genital branch of the genitofemoral nerve can innervate the sensation of the skin of the anterior surface of the scrotum. Does it appears that either nerve choice would lead you to the correct answer?




 -1  upvote downvote
submitted by lisa(0),

The question asks about a nerve that is on the EXTERNAL surface of the espermatic cord at the level of superficial ring, that is the ilioinguinal nerve, because the genital branch of the genitofemoral nerve goes inside.

The trick is that the genitofemoral is responsible of invervating the anterior surface of the escrotum, but the genital branch of the inguinal nerve that goes external is responsible of the superior anterior surface of the scrotum

Here you can see both nerves outside and inside the spermatic cord https://image.slidesharecdn.com/herniasdepared-170305224216/95/hernias-de-pared-10-638.jpg?cb=1488753771 and here you can see the inervation from both nerves https://medicalfoster.com/wp-content/uploads/2017/01/attelu-rezultati-vaicajumam-genitofemoral-nerve.jpeg