Peripheral nerve injury without numbness! - USMLE Forums
USMLE Forums Logo
USMLE Forums         Your Reliable USMLE Online Community     Members     Posts
Home
USMLE Articles
USMLE News
USMLE Polls
USMLE Books
USMLE Apps
Go Back   USMLE Forums > USMLE Step 1 Forum

USMLE Step 1 Forum USMLE Step 1 Discussion Forum: Let's talk about anything related to USMLE Step 1 exam


Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 11-24-2011
USMLE-Syndrome's Avatar
USMLE Forums Master
 
Steps History: ---
Posts: 1,203
Threads: 180
Thanked 1,254 Times in 441 Posts
Reputation: 1268
Question Peripheral nerve injury without numbness!

A 33-year-old woman undergoes a lymph node biopsy of her deep cervical nodes on the left side of her neck. Immediately following surgery, she complains of weakness in her left shoulder. On exam, the left shoulder droops, and she is unable to raise the point of her shoulder. She denies numbness in her shoulder, back, and neck. In most peripheral nerve injuries, there is usually characteristic sensory loss, producing numbness in a specific area. Which of the following best explains why there is no numbness in this case?

A. The motor part of CN XI must have been damaged, while the sensory part remained intact.
B. The spinal accessory nerve is unique among peripheral nerves in that it does not carry any sensory fibers whatsoever.
C. Sensory loss is not expected from damage of this nerve because no peripheral nerve that innervates a skeletal muscle of the upper limb carries sensory fibers.
D. Nerves that innervate skeletal muscles carry only motor neurons, and cutaneous sensory nerves carry only sensory neurons.
Reply With Quote Quick reply to this message
The above post was thanked by:
Abdulaziz (11-26-2011), Glomerulus (11-24-2011), hope12 (05-02-2012), medkary (11-26-2011), Syed Hasan (11-25-2011), umeraulakh (11-24-2011), wimzie (11-27-2011), zohra (11-26-2011)



  #2  
Old 11-24-2011
USMLE Forums Guru
 
Steps History: Step 1 Only
Posts: 342
Threads: 50
Thanked 197 Times in 103 Posts
Reputation: 207
Default

well i think it's a cranial nerve injury, patient can't shrug the shoulders . .

B . . .but it isn't unique . . .
Reply With Quote Quick reply to this message
  #3  
Old 11-24-2011
USMLE Forums Addict
 
Steps History: Step 1 Only
Posts: 154
Threads: 8
Thanked 134 Times in 62 Posts
Reputation: 144
Default

Hey, thanks for the question. I would go with B too.Is it unique?
Reply With Quote Quick reply to this message
 
  #4  
Old 11-24-2011
USMLE Forums Scout
 
Steps History: Not yet
Posts: 46
Threads: 3
Thanked 34 Times in 20 Posts
Reputation: 44
Default

Quote:
Originally Posted by Glomerulus View Post
Hey, thanks for the question. I would go with B too.Is it unique?
It's not unique. C1 is purely motor.
Reply With Quote Quick reply to this message
  #5  
Old 11-25-2011
USMLE-Syndrome's Avatar
USMLE Forums Master
 
Steps History: ---
Posts: 1,203
Threads: 180
Thanked 1,254 Times in 441 Posts
Reputation: 1268
Default

ANSWER B. The spinal accessory n. is, in fact, unique among peripheral nerves in that it does not carry any sensory fibers whatsoever.
CN XI is truly only motor.
Some other motor nerves (e.g., dorsal scapular n.) do not carry any cutaneous sensory neurons, but all nerves to skeletal muscle also carry proprioceptive fibers. These fibers transmit sensory information concerning the state of contraction and position of joints to the central nervous system, allowing for coordination of movement.

A. Though many peripheral nerves innervate both skeletal muscle and skin, the accessory nerve is not one of them.

C. This gross generalization is not true. While it is true that the dorsal scapular n. and spinal accessory n. provide no cutaneous sensory innervation to any part of the body, other nn. of the upper limb, such as the ulnar nerve, have branches that provide innervation to both skeletal muscle and skin. Moreover, most nn. to skeletal muscle also carry proprioceptive fibers that transmit sensory information about the state of contraction of muscles and about the position of joints back to the central nervous system. This information allows for coordinated movement.

D. This is not a valid generalization for most nerves in the body. Cutaneous sensory nerves all carry motor fibers that innervate sweat glands (secretomotor neurons), blood vessel walls (vasomotor neurons), and arrector pili muscles (pilomotor neurons). Motor nerves to skeletal muscle all carry proprioceptive (i.e., sensory) fibers that transmit sensory information about the state of contraction of muscles and about the position of joints back to the central nervous system. This information allows for coordinated movement.
Reply With Quote Quick reply to this message
The above post was thanked by:
Abdulaziz (11-26-2011), Amenah (11-26-2011), deeqwerty (11-26-2011), drortho (02-09-2012), Glomerulus (11-25-2011), indigo (11-25-2011), K06100 (11-26-2011), medkary (11-26-2011), oksana (11-26-2011), USMLEBoy (11-26-2011), zohra (11-26-2011)



Reply

Tags
Nervous-System-, Neuroanatomy-, Pathology-, Step-1-Questions

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the USMLE Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Medical School
Choose "---" if you don't want to tell. AMG for US & Canadian medical schools. IMG for all other medical schools.
USMLE Steps History
What steps finished! Example: 1+CK+CS+3 = Passed Step 1, Step 2 CK, Step 2 CS, and Step 3.

Choose "---" if you don't want to tell.

Favorite USMLE Books
What USMLE books you really think are useful. Leave blank if you don't want to tell.
Location
Where you live. Leave blank if you don't want to tell.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Nerve injury in mid shaft humeral fracture plasticsurgeon USMLE Step 1 Forum 5 09-26-2011 01:02 PM
Traumatic Head Injury and Nerve Cell Concentration! ricko335 USMLE Step 1 Forum 10 08-02-2011 08:08 AM
Difference between Romberg and Peroneal nerve injury gaits docoftheworld USMLE Step 2 CK Forum 0 06-01-2011 05:41 PM
C6 Dorsal Root Ganglion Injury and nerve degeneration adorisz USMLE Step 1 Forum 2 02-08-2011 01:29 AM
Colle's Fracture and Median Nerve Injury Androide89 USMLE Step 1 Forum 1 09-26-2010 10:19 AM

RSS Feed
Find Us on Facebook
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.

USMLE® & other trade marks belong to their respective owners, read full disclaimer
USMLE Forums created under Creative Commons 3.0 License. (2009-2014)