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{{WBRQuestion
{{WBRQuestion
|QuestionAuthor=William J Gibson
|QuestionAuthor=William J Gibson (Reviewed by Serge Korjian)
|ExamType=USMLE Step 1
|ExamType=USMLE Step 1
|MainCategory=Anatomy
|MainCategory=Anatomy
Line 8: Line 8:
|MainCategory=Anatomy
|MainCategory=Anatomy
|SubCategory=Musculoskeletal/Rheumatology, Oncology, General Principles
|SubCategory=Musculoskeletal/Rheumatology, Oncology, General Principles
|MainCategory=Anatomy
|MainCategory=Anatomy
|MainCategory=Anatomy
|MainCategory=Anatomy
|MainCategory=Anatomy
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|MainCategory=Anatomy
|MainCategory=Anatomy
|SubCategory=Musculoskeletal/Rheumatology, Oncology, General Principles
|SubCategory=Musculoskeletal/Rheumatology, Oncology, General Principles
|Prompt=A 52 year old woman presents to her primary care physician after noticing a firm lump in her breast.  She undergoes fine needle aspiration of the mass, which reveals a grade 3 invasive ductal carcinoma with overexpression of the HER2/Neu oncogene.  The woman undergoes surgical resection of the mass and the axillary lymph nodes.  She is treated with adjuvant Trastuzumab and undergoes breast reconstruction.  Two weeks after her surgery, she notices that her scapula protrudes when she lifts her arm.  Which of the following nerves give rise to the affected nerve in this patient?
|Prompt=A 52-year-old woman presents to her primary care physician after noticing a firm lump in her right breast.  She undergoes fine needle aspiration of the mass, which reveals a grade 3 invasive ductal carcinoma with overexpression of the HER2/Neu oncogene.  Following surgical resection of the mass and axillary lymph node dissection, the patient undergoes breast reconstructive surgery.  Two weeks after her surgery, she starts noticing a bony protrusion in her back everytime she lifts her right arm.  Which of the following is the most likely origin of the injured nerve in this patient?
|Explanation=The patient in this vignette has suffered damage to the long thoracic nerve as a result of radical mastectomy.  The long thoracic nerve arises from the C5-C7 nerve roots to innervate the serratus anterior muscle.  The serratus anterior normally serves to abduct the arm beyond 90 degrees to the body.  Lesion of this nerve can lead to “winging” of the scapula.
|Explanation=[[File:Brachial_plexus_long_thoracic_nerve.jpg|900px]]


'''Educational Objective:''' Lesion of the long thoracic nerve, derived from the C5-C7 nerve roots, leads to winging of the scapula.
The patient in this vignette has suffered damage to the long thoracic nerve as a result of radical mastectomy.  The long thoracic nerve arises from the nerve roots of C5-C7 to innervate the serratus anterior muscle.  The serratus anterior normally serves to abduct the arm beyond 90 degrees to the body.  Lesion of this nerve can lead to “winging” of the scapula.
 
'''References:''' First Aid 2012 page 411
|AnswerA=C5-C6
|AnswerA=C5-C6
|AnswerAExp='''Incorrect:''' The C5-C6 nerve roots give rise to the radial nerve and the posterior cord of the brachial plexus.  These nerves are damaged in Erb’s palsy.
|AnswerAExp=The C5-C6 nerve roots give rise to the axillary nerve and the posterior cord of the brachial plexus.  These nerves are damaged in Erb’s palsy.
|AnswerB=C5-C7
|AnswerB=C5-C7
|AnswerBExp='''Correct:'''  The C5-C7 nerve roots give rise to the long thoracic nerve.  The long thoracic nerve innervates the serratus anterior and
|AnswerBExp=The C5-C7 nerve roots give rise to the long thoracic nerve.  The long thoracic nerve innervates the serratus anterior.
|AnswerC=C8-T1
|AnswerC=C8-T1
|AnswerCExp='''Incorrect:''' the C8-T1 nerve roots give rise to the inferior trunk of the brachial plexus.  These nerves are injured in Krumpke’s palsy.
|AnswerCExp=The C8-T1 nerve roots give rise to the inferior trunk of the brachial plexus.  These nerves are injured in Krumpke’s palsy.
|AnswerD=Inferior trunk of the brachial plexus
|AnswerD=Inferior trunk of the brachial plexus
 
|AnswerDExp=The inferior trunk of the brachial plexus is injured in Krumpke’s palsy.
|AnswerDExp='''Incorrect:''' the inferior trunk of the brachial plexus is injured in Krumpke’s palsy.
|AnswerE=Posterior cord of the brachial plexus
|AnswerE=Posterior cord of the brachial plexus
|AnswerEExp='''Incorrect:''' the posterior cord of the brachial plexus gives rise to the axillary and radial nerves.
|AnswerEExp=The posterior cord of the brachial plexus gives rise to the axillary and radial nerves.
|EducationalObjectives=Lesions of the long thoracic nerve, derived from the C5-C7 nerve roots, leads to winging of the scapula.
|References=First Aid 2014 page 413
|RightAnswer=B
|RightAnswer=B
|WBRKeyword=Breast, Nerve, Long thoracic nerve, Brachial, Brachial plexus, Arm, Paralysis, Serratus, Muscle,  
|WBRKeyword=Breast, Nerve, Long thoracic nerve, Brachial, Brachial plexus, Arm, Paralysis, Serratus anterior, Muscle,
|Approved=Yes
|Approved=Yes
}}
}}

Latest revision as of 00:45, 28 October 2020
Author PageAuthor::William J Gibson (Reviewed by Serge Korjian)
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Anatomy
Sub Category SubCategory::Musculoskeletal/Rheumatology, SubCategory::Oncology, SubCategory::General Principles
Prompt [[Prompt::A 52-year-old woman presents to her primary care physician after noticing a firm lump in her right breast. She undergoes fine needle aspiration of the mass, which reveals a grade 3 invasive ductal carcinoma with overexpression of the HER2/Neu oncogene. Following surgical resection of the mass and axillary lymph node dissection, the patient undergoes breast reconstructive surgery. Two weeks after her surgery, she starts noticing a bony protrusion in her back everytime she lifts her right arm. Which of the following is the most likely origin of the injured nerve in this patient?]]
Answer A AnswerA::C5-C6
Answer A Explanation AnswerAExp::The C5-C6 nerve roots give rise to the axillary nerve and the posterior cord of the brachial plexus. These nerves are damaged in Erb’s palsy.
Answer B AnswerB::C5-C7
Answer B Explanation AnswerBExp::The C5-C7 nerve roots give rise to the long thoracic nerve. The long thoracic nerve innervates the serratus anterior.
Answer C AnswerC::C8-T1
Answer C Explanation AnswerCExp::The C8-T1 nerve roots give rise to the inferior trunk of the brachial plexus. These nerves are injured in Krumpke’s palsy.
Answer D AnswerD::Inferior trunk of the brachial plexus
Answer D Explanation AnswerDExp::The inferior trunk of the brachial plexus is injured in Krumpke’s palsy.
Answer E AnswerE::Posterior cord of the brachial plexus
Answer E Explanation AnswerEExp::The posterior cord of the brachial plexus gives rise to the axillary and radial nerves.
Right Answer RightAnswer::B
Explanation [[Explanation::

The patient in this vignette has suffered damage to the long thoracic nerve as a result of radical mastectomy. The long thoracic nerve arises from the nerve roots of C5-C7 to innervate the serratus anterior muscle. The serratus anterior normally serves to abduct the arm beyond 90 degrees to the body. Lesion of this nerve can lead to “winging” of the scapula.
Educational Objective: Lesions of the long thoracic nerve, derived from the C5-C7 nerve roots, leads to winging of the scapula.
References: First Aid 2014 page 413]]

Approved Approved::Yes
Keyword WBRKeyword::Breast, WBRKeyword::Nerve, WBRKeyword::Long thoracic nerve, WBRKeyword::Brachial, WBRKeyword::Brachial plexus, WBRKeyword::Arm, WBRKeyword::Paralysis, WBRKeyword::Serratus anterior, WBRKeyword::Muscle
Linked Question Linked::
Order in Linked Questions LinkedOrder::
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