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Axillary nerve

Branches · C5 C6

Leaves the axilla through the quadrangular space and winds around the surgical neck of the humerus with the posterior circumflex humeral artery.

Traced from the start

  1. C5 nerve rootC6 nerve root
  2. Upper trunk
  3. C7 nerve root
  4. Middle trunk
  5. C8 nerve rootT1 nerve root
  6. Lower trunk
  7. Posterior division of the upper trunkPosterior division of the middle trunkPosterior division of the lower trunk
  8. Posterior cord
  9. Axillary nerve

Detail

Motor
Deltoid. Teres minor
Sensory
The regimental badge area over the lower deltoid, via the superior lateral cutaneous nerve of the arm

When it goes wrong

Fracture of the surgical neck of the humerus, or anterior dislocation of the shoulder

Abduction is lost beyond about 15 degrees — supraspinatus still initiates the first 15, but without deltoid the arm cannot be raised to 90 — with deltoid wasting that flattens the shoulder contour and numbness over the regimental badge area.

Practise this structure

1 question in the bank tagged Axillary Nerve.

A 24-year-old man returns to clinic three weeks after coming off his motorbike onto his right shoulder. Radiographs at the time showed a fracture through the su…

Foundations · common