Nerves

• The Axillary Nerve:

  • Arises from the ventral rami of C5 and 6, the superior trunk (posterior division) & the posterior cord.

  • In the axilla, it passes posterior to the axillary artery & anterior to subscapularis.

  • It passes close to the inferior aspect of the shoulder joint & through the quadrilateral space.

  • It divides into anterior and posterior branches

  • It then winds around the surgical neck of the humerus

  Motor supply: Deltoid and Teres minor muscles

  Sensory supply: Skin on the lateral aspect of the shoulder (via the upper lateral cutaneous nerve of the arm
• The Musculocutaneous Nerve:

  • Arises from the ventral rami of C5, 6 & 7, the superior & middle trunks (anterior divisions) & the lateral cord.
  • In the axilla it lies lateral to the axillary artery.
  • It descends into the arm by piercing coracobrachialis
  • It then runs distally between biceps and brachialis into the lateral side of the arm.
  • At the elbow it becomes the lateral cutaneous nerve of the forearm which emerges laterally from underneath biceps.
• Musculocutaneous Nerve:

  Motor supply: Biceps brachii, medial part of brachialis & coracobrachialis

  Sensory supply: Skin on the lateral half of the forearm down to the base of the thumb (via the lateral cutaneous nerve of the forearm).
• Median Nerve:

  • Arises from C5, 6, 7, 8, T1, the superior, middle & inferior trunks (anterior divisions) & the lateral and medial cords
  • It enters the arm from the axilla at the inferior margin of teres major and passes down the medial side of the arm under cover of biceps brachii.
  • In the lower part of the arm it lies on brachialis and enters the cubital fossa.

  Motor supply: Pronator teres, Pronator quadratus and muscles of the forearm

  Sensory supply: Articular branches to the elbow joint
• Ulnar Nerve:

  • Arises from the ventral rami of C8 and T1 (and occasionally C7), the inferior trunk (anterior division) and the medial cord.
  • Runs medial to axillary artery and descends down medial to brachial artery and anterior to triceps.
  • Half way down the arm the ulnar nerve pierces the intermuscular septum to enter posterior compartment of arm
  • It lies on the medial head of triceps down and runs down to the medial epicondyle of the humerus and lies in the ulnar groove behind the medial epicondyle (funny bone), before entering the forearm.
• Ulnar Nerve:

  Motor supply: Muscles of the forearm

  Sensory supply: Articular branches to the elbow joint
• Radial Nerve:

  • Arises from C5, 6, 7, 8, T1, the superior, middle & inferior trunks & the posterior cord.
  • Lies behind axillary artery in the axilla & passes anterior to subscapularis, latissimus dorsi & teres major tendons
  • Enters the posterior aspect of the arm via the triangular space (formed by the humerus laterally, the long head of triceps medially & teres major superiorly).
  • Along the radial groove of the humerus (medial to lateral)
• Radial Nerve: (2)

  • Along the radial groove of the humerus (medial to lateral)
  • Runs between the lateral and medial heads of the triceps
  • It pierces intermuscular septum to enter the anterior compartment
  • Divides into the superficial and deep branches anterior to the lateral epicondyle
• Radial Nerve: (3)

  Motor supply: Triceps, anconeus, brachialis (lateral 1/3), brachioradialis, supinator and muscles of the forearm

  Sensory supply: Skin on back of arm and forearm (via posterior cutaneous nerve of arm, the lower lateral cutaneous nerve of arm and posterior cutaneous nerve of forearm). Articular branches to the elbow.