axillary nerve (circumflex nerve)

Origin

• posterior cord of the brachial plexus

Innervation

• deltoid
• teres minor

Course

• the nerve originates from the posterior cord of the brachial plexus in the axilla, passes laterally & posteriorly through the quadrangular space with the posterior circumflex humeral artery, winds round the surgical neck of the humerus to supply the deltoid & teres minor muscles, terminating as the superior lateral brachial cutaneous nerve

Branches

• superior lateral brachial cutaneous nerve

Pathology

• subject to injury from
  • anterior shoulder dislocation
  • falling on an outstretched hand
• paresthesias & diminished sensation to light touch over the lateral aspect of the shoulder
• weakness with abduction & external rotation of the arm

More general terms

• peripheral nerve