Identify the axillary nerve and the posterior circumflex humeral artery as they enter the deep surface of the deltoid muscle. To expose the nerve and blood vessels to the deltoid muscle, detach it from its attachments to the spine and acromion process of the scapula and reflect the deltoid muscle laterally. The axillary nerve is a branch of the posterior cord of the brachial plexus [tip of the scissors]. This nerve provides motor innervation to the deltoid and teres minor muscles. The posterior humeral circumflex artery [to be dissected in another exercise] is one of three main branches that arise from the third part of the axillary artery.
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