Nerves of the arm

• Axillary nerve

  Arises from c5, c6, superior trunk (posterior division) and posterior cord

  In the axilla is passes posterior to axially artery and anterior to the subscapularis

  It passes inferior to the shoulder joint (which it innervates) + through the quadrilateral space.

  It then divides into anterior and posterior branches

  • It then winds around the surgical neck of humerus 

  Motor supply: Deltoid + teres minor muscles

  Sensory: skin on lat aspect of shoulder (via the upper lateral cutaneous nerve of the arm) 
• Musculocutaneous nerve


  Arises from C5,C6 and 7, the superior and middle trunks (anterior divisions) and the lateral cord
• Musculocutaneous nerve

  • In the axilla it is lateral to the axillary artery
  • It descends into the arm by piercing coracobrachialis(which it also innervates)
  • It then runs distally between biceps and brachialis to reach the lateral side of the arm
  • At the elbow it becomes the lateral cutaneous nerve of the forearm which emerges laterally underneath biceps to become superficial and supply the skin on the lateral half of the forearm down to the base of the thumb
• Median nerve

  Arises from C5, 6,7,8,T1, the superior, middle and inferior trunks (anterior divisions) and the lateral and medial cords
• Median nerve path

  1. Enters the arm from the axilla at the inferior margin of teres major

  2. Passes down the medial side of the arm under cover of biceps brachii

  3. Lies anterior to the elbow joint in the cubital fossa, deep to the bicipital aponeurosis

  4. Enters the forearm between the 2 heads of pronator teres

  5. Runs below the tendinous arch of FDS and then distally between FDS and FDP to the wrist

  6. Becomes superficial, appearing between the tendons of FDS & FCR just above the wrist

  7. Travels under the flexor retinaculum to enter the hand, passing anterior to the long flexor tendons within the carpal tunnel

  8. Divides into lateral (recurrent) and medial branches in the hand
• Median nerve


  • Motor supply: Pronator teres, FCR, palmaris longus and FDS
  • Sensory supply: articular branches to the elbow joint
• Radial nerve


  Arises from c5,6,7,8, T1 the superior, middle and inferior trunks (posterior divisions) and the posterior cord
• Radial nerve course


  1. Lies posterior to the axillary artery in the axilla

  2. Passing anterior to the tendons of subcapularis, latissimus doors and teres major

  3. Enters the posterior aspect of the arm via the triangular space

  4. Runs obliquely inferolaterally along the radial groove on the posterior aspect of the humerus between the medial and lateral heads of triceps

  5. Reaches the lateral border of the humerus in the distal 1/3 of the arm
• Ulnar nerve


  Arises from the ventral rami of c8,T1 (sometimes C7), the inferior trunk(anterior division) and the medial cord
• Ulnar nerve path


  1. Enters the arm medial to the axiallary artery

  2. Descends the arm medial to the brachial artery and anterior to triceps

  3. Half way down the arm the ulnar nerve passes posteriorly, piercing the medial inter muscular septum to enter the posterior compartment of the arm

  4. At the elbow it passes behind the medial epicondyle of the humerus in the ulnar groove before entering the forearm

  5. In the forearm, the ulnar nerve passes into the anterior compartment by passing between the 2 heads of FCU

  6. It then descends down the medial side forearm between FCU and FDP

  7. At the wrist the nerve lies lateral to the FCU tendon and medial to the ulnar artery

  8. It crosses over the flexor retinaculum into the hand where it divides into superficial and deep branches within Guyom's canal (between the hook of hamate and the pisiform)
• Ulnar Motor supply


  FCU and medial 1/2 FDP
• Ulanar Sensory supply

  Articular branch to the elbow
• Superficial branch of radial nerve begins anterior to lat epicondyle, descends along anterolateral side of forearm covered by brachioradialis.

  • 2/3 of way down forearm the nerve emerges posteriorly from underneath tendon ofbrachioradialis to become superficial.
  • It then passes laterally and posteriorly over the radius and the divides into four or five digital branches.
• Superficial branch of radial nerve MOTOR SUPPLY: None SENSORY SUPPLY: Supplies skin on the dorsolateral aspect of the wrist and hand, the dorsum of the lateral 3 1⁄2 digits as far as the distal IP joints and articular branches to the MCP and PIP joints.