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{{WBRQuestion
{{WBRQuestion
|QuestionAuthor={{Rim}}
|QuestionAuthor= {{SSK}} {{Alison}} (Reviewed by Serge Korjian)
|ExamType=USMLE Step 1
|ExamType=USMLE Step 1
|MainCategory=Anatomy
|MainCategory=Anatomy
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|MainCategory=Anatomy
|MainCategory=Anatomy
|SubCategory=Head and Neck
|SubCategory=Head and Neck
|MainCategory=Anatomy
|MainCategory=Anatomy
|MainCategory=Anatomy
|MainCategory=Anatomy
|MainCategory=Anatomy
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|MainCategory=Anatomy
|MainCategory=Anatomy
|SubCategory=Head and Neck
|SubCategory=Head and Neck
|Prompt=A 42-year-old male patient presents to the physician's office with complaints of an inability to laterally flex his neck or rotate his head. Upon physical examination, which other finding is most likely demonstrated in this patient?
|Prompt=A 42-year-old man presents to the physician's office with complaints of right shoulder pain radiating to the neck and upper back for the past 3 weeks. He reports that the pain started after getting hit on the neck during a recent basketball game. Physical exam reveals normal passive motion but limited sustained abduction and elevation of the shoulder. Which other finding is most likely to be present in this patient?
|Explanation=The patient is presenting with signs consistent with injury to the sternocleidomastoid muscle, which is responsible for the lateral flexion of the neck and the rotation of the head. The sternocleidomastoid muscle originates in the anterior and superior manubrium and superior medial third of the clavicle and inserts in the lateral aspect of the mastoid process and anterior half of the superior nuchal line. It attaches the sternum, the clavicle, and the mastoid and occipital bones. The sternocleidomastoid is innervated by CN XI, or the spinal accessory nerve, which also innervates the trapezius, the main muscle responsible for the elevation of the shoulder.
|Explanation=The patient in this scenario likely suffered an injury to his spinal accessory nerve secondary to neck trauma. The spinal accessory nerve is the eleventh cranial nerve that arises mostly from the spinal cord. Only a small portion of the spinal accessory nerve originates from the nucleus ambiguus and eventually joins the vagus nerve.  The spinal portion arises from a column of nuclei in the ventral medulla. The nerve supplies both the sternocleidomastoid (SCM) and trapezius muscles. The sternocleidomastoid muscles originate from the sternum and clavicle and inserts on the mastoid process. The SCM rotates the head contralaterally and flexes the neck ipsilaterally. Patients with accessory nerve injury classically present with shoulder pain, weakness with sustained shoulder abduction, and difficulty shrugging shoulder. Signs in the SCM include weakness with ipsilateral neck flexion and contralateral head rotation.
 
|AnswerA=Inability to laterally flex the neck
|EducationalObjectives= Sternocleidomastoid laterally flexes the neck and rotates the head. It is innervated by CN XI. The trapezius muscle, which elevates the shoulder, is also innervated by CN XI.
|AnswerAExp=Cranial nerve (CN) XI or the spinal accessory nerve innervates the sternocleidomastoid, which is the muscle responsible for ipsilateral neck flexion and contralateral head rotation.
|References= First Aid 2014 page 67
|AnswerA=Inability to elevate his shoulder
|AnswerAExp=Cranial nerve (CN) XI or the spinal accessory nerve innervates the trapezius, which is the muscle responsible for elevation or shrugging of the shoulder.
|AnswerB=Inability to open his jaw
|AnswerB=Inability to open his jaw
|AnswerBExp=The lateral pterygoid is the main muscle the opens the jaw. All jaw muscles are innervated by the trigeminal nerve - the mandibular branch (CN V3).
|AnswerBExp=The lateral pterygoid is the main muscle responsible for opening the jaw. All jaw muscles are innervated by the trigeminal nerve - the mandibular branch (CN V3).
|AnswerC=Inability to protrude his tongue
|AnswerC=Inability to protrude his tongue
|AnswerCExp=CN XII or hypoglossal nerve is the nerve responsible for tongue motor function.
|AnswerCExp=The CN XII or the hypoglossal nerve innervates the tongue.
|AnswerD=Inability to elevate his arm
|AnswerD=Inability to abduct arm
|AnswerDExp=Elevation of arm is achieved by the deltoid muscles and to some extent by the supraspinatus muscle. The deltoid muscle is innervated by the axillary (C5-C6) nerve. The supraspinatus muscle is innervated by the suprascapular (C5-C6) nerve.
|AnswerDExp=Arm abduction relies on the deltoid muscles and the supraspinatus muscle. The deltoid muscle is innervated by the axillary (C5-C6) nerve. The supraspinatus muscle is innervated by the suprascapular (C5-C6) nerve.
|AnswerE=Inability to swallow
|AnswerE=Inability to swallow
|AnswerEExp=Swallowing is mainly achieved by CN IX or the glossopharyngeal nerve.
|AnswerEExp=Swallowing involves several cranial nerves most importantly CN IX or the glossopharyngeal nerve.
|EducationalObjectives=The spinal accessory nerve (CN XI) supplies the sternocleidomastoid (SCM) muscles responsible for ipsilateral neck flexion and contralateral head rotation, and the trapezius muscles responsible for shoulder elevation.
|References=Walker HK, Hall WD, Hurst JW, editors. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition. Boston: Butterworths; 1990. Chapter 64.<br>
First Aid 2014 page 472
|RightAnswer=A
|RightAnswer=A
|WBRKeyword=trapezius, sternocleidomastoid, shoulder, elevate, elevation, physical, examination, exam, muscle, innervate, innervation, cranial, nerve, 11, XI, spinal, accessory, nerve, shrug, shrugging, lateral, flex, flexion, rotate, rotation, head
|WBRKeyword=Trapezius, Sternocleidomastoid, SCM, Cranial nerves, CNXI, Cranial nerve injuries,
|Approved=No
|Approved=Yes
}}
}}

Latest revision as of 00:11, 28 October 2020
Author [[PageAuthor::Serge Korjian M.D. (Reviewed by Alison Leibowitz) (Reviewed by Serge Korjian)]]
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Anatomy
Sub Category SubCategory::Head and Neck
Prompt [[Prompt::A 42-year-old man presents to the physician's office with complaints of right shoulder pain radiating to the neck and upper back for the past 3 weeks. He reports that the pain started after getting hit on the neck during a recent basketball game. Physical exam reveals normal passive motion but limited sustained abduction and elevation of the shoulder. Which other finding is most likely to be present in this patient?]]
Answer A AnswerA::Inability to laterally flex the neck
Answer A Explanation AnswerAExp::Cranial nerve (CN) XI or the spinal accessory nerve innervates the sternocleidomastoid, which is the muscle responsible for ipsilateral neck flexion and contralateral head rotation.
Answer B AnswerB::Inability to open his jaw
Answer B Explanation AnswerBExp::The lateral pterygoid is the main muscle responsible for opening the jaw. All jaw muscles are innervated by the trigeminal nerve - the mandibular branch (CN V3).
Answer C AnswerC::Inability to protrude his tongue
Answer C Explanation AnswerCExp::The CN XII or the hypoglossal nerve innervates the tongue.
Answer D AnswerD::Inability to abduct arm
Answer D Explanation AnswerDExp::Arm abduction relies on the deltoid muscles and the supraspinatus muscle. The deltoid muscle is innervated by the axillary (C5-C6) nerve. The supraspinatus muscle is innervated by the suprascapular (C5-C6) nerve.
Answer E AnswerE::Inability to swallow
Answer E Explanation AnswerEExp::Swallowing involves several cranial nerves most importantly CN IX or the glossopharyngeal nerve.
Right Answer RightAnswer::A
Explanation [[Explanation::The patient in this scenario likely suffered an injury to his spinal accessory nerve secondary to neck trauma. The spinal accessory nerve is the eleventh cranial nerve that arises mostly from the spinal cord. Only a small portion of the spinal accessory nerve originates from the nucleus ambiguus and eventually joins the vagus nerve. The spinal portion arises from a column of nuclei in the ventral medulla. The nerve supplies both the sternocleidomastoid (SCM) and trapezius muscles. The sternocleidomastoid muscles originate from the sternum and clavicle and inserts on the mastoid process. The SCM rotates the head contralaterally and flexes the neck ipsilaterally. Patients with accessory nerve injury classically present with shoulder pain, weakness with sustained shoulder abduction, and difficulty shrugging shoulder. Signs in the SCM include weakness with ipsilateral neck flexion and contralateral head rotation.

Educational Objective: The spinal accessory nerve (CN XI) supplies the sternocleidomastoid (SCM) muscles responsible for ipsilateral neck flexion and contralateral head rotation, and the trapezius muscles responsible for shoulder elevation.
References: Walker HK, Hall WD, Hurst JW, editors. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition. Boston: Butterworths; 1990. Chapter 64.
First Aid 2014 page 472]]

Approved Approved::Yes
Keyword WBRKeyword::Trapezius, WBRKeyword::Sternocleidomastoid, WBRKeyword::SCM, WBRKeyword::Cranial nerves, WBRKeyword::CNXI, WBRKeyword::Cranial nerve injuries
Linked Question Linked::
Order in Linked Questions LinkedOrder::
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