Which one of the following muscles would be affected by damage to the thoracodorsal nerve?

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Question restatement: Which one of the following muscles would be affected by damage to the thoracodorsal nerve?

Option a: Teres major. While Teres major is near the thorax and participates in adduction and medial rotation of the humerus, it is innervated primarily by the lower subscapular nerve, not the thoracodorsal nerve. Therefore, damage to the thoracodorsal nerve would not primarily disrupt Teres major function.

Option b: Latissimus dorsi. Latissimus dorsi is the muscle classically innervated by the thoracodorsal nerve (also known as the middle subscapular nerve). This nerve supplies motor fibers that enable actions like adduction, extension, and medial rotation of the humerus. If the thoracodorsal nerve is compromised, Latissimus dorsi would show weakness or paralysis in these movements, making this the muscle directly affected by such a lesion.

Option c: Rhomboid major. Rhomboid major receives innervation from the dorsal scapular nerve. Damage to the thoracodorsal nerve would not primarily impact Rhomboid major, so this option does not align with thoracodorsal involvement.

Option d: Serratus anterior. Serratus anterior is innervated by the long thoracic nerve. While this nerve runs in the same regional area as the thoracodorsal nerve, its motor supply is distinct, so thoracodorsal nerve damage would not principally affect Serratus anterior.

Option e: Levator scapulae. Levator scapulae is supplied mainly by dorsal scapular nerve and cervical nerves. It would not be the primary muscle affected by thoracodorsal nerve injury, so this option is unlikely.

Summary: The thoracodorsal nerve specifically innervates Latissimus dorsi, enabling shoulder adduction, extension, and medial rotation. Other listed muscles have different innervation patterns (teres major by lower subscapular nerve; rhomboids by dorsal scapular nerve; Serratus anterior by long thoracic nerve; levator scapulae by dorsal scapular and cervical nerves), so their function would be preserved or variably affected only if there were broader nerve damage. The key distinction is the direct innervation link between the thoracodorsal nerve and Latissimus dorsi, which sets this option apart as the one most impacted by thoracodorsal injury.

Dashboard ASSESSABLE Pectoral Girdle and Shoulder Quiz

Which one of the following muscles would be affected by damage to the thoracodorsal nerve?

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