The lateral, medial and posterior cords give branches supplying muscles and skin of the upper limb.
Lateral cord
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The lateral pectoral nerve supplies both pectoralis major and pectoralis minor.
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The musculocutaneous nerve supplies coracobrachialis, both heads of biceps brachii and brachialis.
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The lateral root of the median nerve joins the medial root. The median nerve is the chief nerve of the muscles of the front of the forearm and the thenar eminence.
Medial cord
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The medial pectoral nerve also supplies pectoralis minor and pectoralis major.
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The medial cutaneous nerve of arm carries sensation from a small area on the medial side of the arm. The medial cutaneous nerve of forearm carries sensation from a large area on the medial side of the forearm.
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C7 fibres reach the ulnar nerve through a communicating branch from the lateral root of the median nerve.
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The ulnar nerve supplies one and a half muscles of the front of the forearm and 15 intrinsic muscles of the palm.
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The medial root of the median nerve joins the lateral root and is distributed through the branches of the median nerve.
Posterior cord
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The upper subscapular nerve supplies subscapularis. The lower subscapular nerve assists in supplying subscapularis and also supplies teres major.
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The thoracodorsal nerve, also called the nerve to latissimus dorsi, supplies only latissimus dorsi.
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The axillary nerve, also called the circumflex nerve, supplies deltoid and teres minor.
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The radial nerve is the thickest branch of the brachial plexus. It supplies all three heads of triceps brachii and 12 muscles on the back of the forearm.
Additional nerve supply near the trunk
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Near the trunk, the upper limb also receives supraclavicular branches of the cervical plexus and the intercostobrachial branch of the second intercostal nerve.
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Sympathetic nerves are distributed through the brachial plexus.