Axillary Nerve

 What is the origin and root value of axillary nerve?

• Origin and root value : Axillary nerve is a branch of posterior cord of brachial plexus. Its root value is C5,C6 segments of spinal cord.

 Describe the course of axillary nerve.

• Axillary nerve arises in the axilla from posterior cord of brachial plexus behind the third part of axillary artery.
• It then runs backwards in close relation to the capsule of shoulder joint .
• Enters and  passes backwards through the quadrangular space.
• It terminates by dividing into anterior and posterior divisions.
• Anterior branch accompanies the posterior circumflex humeral vessels  and winds around the surgical neck of humerus, deep to deltoid.
• Posterior branch pierces deep fascia along the posterior border of lower part of deltoid and continues as upper lateral cutaneous nerve of arm.

 Name the branches and structures supplied by the axillary nerve.

Branches and distribution:

•  Branch to capsule of shoulder joint
• Anterior branch supplies:
  • Deltoid muscle
  • Skin over anteroinferior part of deltoid muscle.
• Posterior branch supplies:
  • Teres minor and deltoid muscle (the branch to teres minor bears pseudoganglion)
  • It continues as upper lateral cutaneous nerve of the arm which supplies the skin over the lower half of deltoid.

 Applied Aspect