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NBME 22 Answers

nbme22/Block 2/Question#11

A 52-year-old man comes to the physician because a ...

Sensation from the anterior surface of the scrotum

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 +3  upvote downvote
submitted by hello(79),

The Q is describing the genitofemoral nerve, which runs on the external surface of the spermatic cord at the superficial inguinal ring

This Q is NOT referring to ilioinguinal nerve -- the ilioinguinal nerve exits THROUGH the superficial inguinal canal whereas this Q is asking about a nerve that is EXTERNAL to the superficial inguinal canal.

See http://www.groinpainclinic.co.uk/data/images/nervesaffected.jpg





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 +  




 +3  upvote downvote
submitted by meningitis(176),

Actually, I correct myself: I looked closer and the Genito femoral has an external Spermatic branch and a Lumboinguinal branch. I thought it was the Genitofemoral nerve because the genital branch passes through the deep inguinal ring, enters the inguinal canal, goes to spermatic cord and supplies the cremaster and scrotal skin.

Heres the image: https://upload.wikimedia.org/wikipedia/commons/e/e4/Gray824.png

Correct me if I am wrong please.

gh889  I think you're right, FA2019 pp444 even states that sensory to the scrotum is via the Genitofemoral nerve +2  




 +2  upvote downvote
submitted by mattnatomy(21),

I believe they're referring to compression of branches of the Ilioinguinal Nerve (possibly the Anterior Scrotal Nerves.

Source: https://en.wikipedia.org/wiki/Anterior_scrotal_nerves

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  upvote downvote
submitted by amd(1),

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





 +1  upvote downvote
submitted by d_holles(41),

I got this one via process of elimination. Not sure how you are supposed to remember all that shit.





 +0  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?





 +0  upvote downvote
submitted by diabetes(3),

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.





 +0  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





 +0  upvote downvote
submitted by socialismkills(0),

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





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