Chapter 5 - Brachial Plexus

• A plexus is a network
• Four primary nerve plexuses

  • Cervical plexus
  • Brachial plexus
  • Lumbar plexus
  • Sacral plexus

  
• Brachial plexus


  Network of nerves that supply sensation and motor function to upper extremity

  
• Brachial plexus is formed by ventral primary rami of lowest four cervical and uppermost thoracic nerve (C5-T1)

  
• Roots of Brachial Plexus

  • The ventral rami of spinal nerves C5 to T1

  
• Formation of Brachial Plexus


  1. Roots

  2. Trunks

  3. Divisions

  4. Cords

  5. Terminal branches
• Formation of Brachial Plexus - Roots

  The ventral rami of spinal nerves C5 to T1 are referred to as the roots of the plexus

  
• Formation of Brachial Plexus - Trunks

  1. 5 roots unite to form three trunks

  2. C5 & C6 unite to form superior trunk

  3. C7 continues as middle trunk

  4. C8 & T1 unite to form inferior trunk
• Formation of Brachial Plexus - Divisions

  1. Each trunk splits into anterior and posterior division

  2. Anterior divisions usually supply flexor muscles

  3. Posterior divisions usually supply extensor muscles
• Formation of Brachial Plexus - Cords

  1. Anterior divisions of superior and middle trunks unite to form lateral cord

  2. Anterior division of lower trunk forms medial cord

  3. All 3 posterior divisions unite to form posterior cord
• Terminal branches of Brachial Plexus

  • Musculocutaneous n.
  • Axillary n.
  • Radial n.
  • Median n.
  • Ulnar n.

  
• Musculocutaneous n.


  Supplies the flexors of the arm
• Axillary n.


  Supplies the deltoid and teres minor muscles
• Radial n.


  Supplies the muscles on the posterior aspect of the arm and forearm
• Median n.


  Supplies most of the muscles of the anterior forearm and some of the muscles of the hand
• Ulnar n.


  Supplies the anteromedial muscles of the forearm and most of the muscles of the hand
• Common causes of brachial plexus injuries

  • Severe traction with the arm in abduction
  • Shoulder dislocation
  • Stab or gunshot wound
  • Blunt force trauma
  • Poor posture
  • Chronic repetitive stress
• Patients with brachial plexus injuries commonly present with pain and/or muscle weakness (anesthesia), partial or complete muscle paralysis
• Some patients may experience muscle atrophy
• Mechanisms of injury for Brachial Plexus

  • Vacuum extractor delivery
  • Forceps delivery
  • Falling on shoulder
  • Excessive stretching
  • Direct blow
• Presentation/Characteristic of Brachial Plexus injuries