Musculocutaneous Nerve

Original Editor - Lucinda Hamilton Top Contributors -

Description[edit | edit source]

Nerves of the left upper extremity.gif

The Musculocutaneous nerve is a large branch of the Brachial Plexus.It is called musculocutaneous nerve as it supplies the muscles of the front of the arm and skin of lateral side of forearm.[1]

The Musculocutaneous nerve is a terminal branch of the lateral cord of the Brachial Plexus. It emerges at the inferior border of Pectoralis minor muscle.It passes lateral to the axillary and upper part of brachial artery. It leaves the axilla to then pierce the Corocobrachialis near it humeral insertion to lie in the intermuscular septum between biceps brachii and brachialis muscles.Then it enters the elbow by piercing deep fascia and terminates as the Lateral Cutaneous nerve of the forearm.[1]

[2]

Root[edit | edit source]

Ventral rami of C5, C6, C7

Branches[edit | edit source]

[1]Motor branches to[1]:

  • Corocobrachialis
  • Brachialis ( also has supply from Radial nerve)
  • Biceps Brachii(both long head and short head)

Sensory branches[1]:

  • lateral cutaneous nerve to the lateral forearm (both front and back)

Articular branches[1]:

Movements Produced[edit | edit source]

  • Coracobrachialis - flexes and adducts the glenohumeral (GH) joint and acts to stabilise the humeral head in the glenoid fossa when the arm is hanging freely by side.[3]
  • Brachialis- flexion of the elbow joint.
  • Biceps Brachii- a weak abductor of GH joint when arm externally rotated, weak flexor of GH joint, helps to stabilise GH joint when weight carried in arm, supinator and flexor of the elbow joint.[4]

Pathology/Injury[edit | edit source]

Isolated injuries of the Musculocutaneous Nerve are rare. It may become injured by[5][6]:

  • Brachial Plexus damage
  • Compression injury eg weight lifting or sports involving lots of forarm flexing and supination.The biceps aponeurosis and tendon compress against the fascia of the brachialis muscle causing sensory loss below the elbow on the lateral side of the forearm.
  • Dislocation of the shoulder
  • Shoulder surgery
  • Entrapment of the nerve at the elbow

Anatomical Variations[edit | edit source]

Considerable anatomical variations present with this nerve. This may lead to clinical implications in surgery, diagnosis.[5]

Physiotherapy Techniques[edit | edit source]

Examination[edit | edit source]

  • Check sensation on lateral forearm

Physiotherapeutic Techniques[edit | edit source]

References[edit | edit source]

  1. 1.0 1.1 1.2 1.3 1.4 1.5 Chaurasia BD. Human Anatomy.6th ed. Vol1,CBS Publisers and distributors Pvt Ltd.
  2. Osama Eqeel. Musculocutaneous nerve. Available from: https://www.youtube.com/watch?v=46PTcikRi44 (last accessed 20.3.2019)
  3. Saladin KS. "The Muscular System." Anatomy & Physiology: The Unity of Form and Function. New York, NY: McGraw-Hill, 2012. 346. Print.
  4. Kleiber T, Kunz L, Disselhorst-Klug C. Muscular coordination of biceps brachii and brachioradialis in elbow flexion with respect to hand position. Frontiers in physiology. 2015 Aug 6;6:215.
  5. 5.0 5.1 Patient. Musculocutaneous nerve. Available from: https://patient.info/doctor/musculocutaneous-nerve-lesion-c5-c6 (last accessed 20.3.2019)
  6. Healthline. Musculocutaneous nerve. Available from: https://www.healthline.com/human-body-maps/musculocutaneous-nerve#1 (last accessed 20.3.2019)