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Long Thoracic Nerve

Key Points:
• Innervates the serratus anterior muscle.
• Originates from roots C5, C6, C7, C8.
• There exists a specific type of scapular winging for serratus anterior deficit.
Physical examination of the long thoracic nerve includes motor examination of the serratus anterior muscle.
Detailed Examination Links:
Serratus anterior
Summarized Examination:
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• Scapular winging, due to the the scapula being internally rotated and anteriorly tilted.
Pathological Findings:

• If the long thoracic (serratus anterior) is dysfunctional, patients will exhibit significant lost of shoulder flexion with moderate lost of shoulder abduction. Shoulder flexion < shoulder abduction in terms of affected function.
• The serratus anterior assists in scapula positioning for shoulder flexion, therefore this movement is significantly affected. The trapezius allows for the rotation of the scapula in the adducted position, thus enabling full shoulder abduction, therefore this movement is less significantly affected.

Clinical Relevance:
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Relevant Anatomy:
• Roots: C5, C6, C7, C8.
• Nerve: Long thoracic nerve.
• Muscles Innervated: Serratus anterior.
• Innervation Route: C5, C6, C7, C8 → long thoracic nerve → serratus anterior.