The upper and middle trucks of the brachial plexus combine to form the ____ cord.

Question

Options

• ALateral
• BPosterior
• CMedial
• DAnterior

• A
  78% (36)
• B
  4% (2)
• C
  11% (5)
• D
  7% (3)

Explanation

Option A (Lateral) is correct because the anterior divisions of the upper trunk (C5-C6) and middle trunk (C7) converge to form the lateral cord of the brachial plexus, which is named for its position lateral to the axillary artery.

Option B (Posterior) is wrong - the posterior cord forms from the posterior divisions of all three trunks (upper, middle, and lower). Option C (Medial) is wrong - the medial cord arises solely from the anterior division of the lower trunk (C8-T1). Option D (Anterior) is not a real cord of the brachial plexus; the cords are named lateral, posterior, and medial based on their relationship to the axillary artery.

Memory tip: Think "Upper + Middle = Outside" - the lateral cord comes from the two upper trunks, and "lateral" means outside/away from center. Alternatively, recall the mnemonic "LAT = Upper + Mid" (Lateral = Upper trunk + Middle trunk Anterior divisions).

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