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The brachial plexus is an arrangement of nerve fibres (a Plexus ) running from the spine ( Vertebrae C5-T1), through the neck, the Axilla (armpit region), and into the arm. All nerves of the arm stem form the brachial plexus (with the exception of the intercostobrachialis nerve which supplies an area of skin near the axilla). Therefore, lesions of the plexus can lead to severe functional impairment.


ANATOMY

The brachial plexus starts from the five ventral rami of the .

  • The '' Posterior Cord '' is formed from the three posterior divisions of the trunks.

  • The '' Lateral Cord '' is the anterior divisions from the upper and middle trunks.

  • The '' Medial Cord '' is simply a continuation of the lower trunk.



Branches of the brachial plexus


3 branches from the ''roots''

# Dorsal Scapular Nerve




1 branch from the ''trunks''

# Suprascapular Nerve


3 branches from the ''lateral cord''

# Lateral Pectoral Nerve


  • supplies C5, C6 and C7 fibres to the median nerve.



5 branches from the ''posterior cord''

# Upper Subscapular Nerve






5 branches from the ''medial cord''

# Medial Pectoral Nerve



  • supplies medial skin of the forearm from C8 and T1

    • # Ulnar Nerve



ANESTHESIA OF THE BRACHIAL PLEXUS

The fact that the nerves of the brachial plexus are grouped together acts as a benefit as well. Local Anesthetic s such as Lidocaine or Bupivacaine can be Inject ed in close proximity to these Nerve s, rendering an entire arm insensate and immobile. The process of injecting local anesthetic for this purpose is called Regional Nerve Blockade or more simply, a nerve block, and it is a common procedure in Anesthesia . After an onset time of approximately 10 to 15 minutes, the targeted arm will be fully anesthetized and ready for Surgery . The patient can remain awake during the ensuing surgical procedure, or he can be sedated with medications or fully anesthetized with General Anesthesia as the situation requires.


Peripheral nerve blockade

The use of peripheral nerve blockade (in this case, a "brachial plexus nerve block") offers several advantages when compared to general anesthesia or local anesthesia:
  • The patient can remain awake and breathing on their own, thus protecting themselves from aspiration of stomach contents into the lungs. By avoiding general anesthesia, patients with adverse reactions to general anesthetics (''viz.'' malignant hyperthermia, severe post-operative nausea and vomiting, known hypersensitivity to agents) can be successfully treated. Similarly, patients who experience nuisance side effects from general anesthesia such as nausea, vomiting, or excessive sleepiness can minimize these symptoms.

  • There is no need to perform an Endotracheal Intubation , the procedure of inserting a breathing tube into the trachea. Occasionally, such intubation is unexpectedly difficult to perform, causing injury to the patient.

  • The affected limb's Sympathetic Nerve s are anesthetized, leading to Vasodilation . This improves Blood Flow to the affected limb and makes microvascular surgical procedures technically simpler.

  • The limb can remain numb for several hours after surgery, providing excellent pain relief.

  • Deep and superficial structures of the limb are similarly anesthetized, allowing extensive Surgical Exploration and correction to occur. This is in contrast to locally injected local anesthetics, which tend only to numb superficial structures in the immediate vicinity of the injection.



Brachial plexus blockade

Brachial plexus blockade is the preferred anesthetic technique when:
  • Surgery is expected to be limited either to a region between the midpoint of the Humerus and the Finger s (in which case the brachial plexus block should be either a Supra-clavicular , Infra-clavicular , subcoracoid, or axillary block), OR surgery is expected to be limited to a region between the midpoint of the humerus and the shoulder (in which case the brachial plexus block should be an interscalene block). Because of the distribution of the local anesthetics on the various portions of the brachial plexus, surgeries crossing the midpoint of the humerus often reveal patchy, unanesthetized portions of the arm. Such procedures probably should not be performed under regional nerve block alone.

    • AND

  • There are no contra-indications to a block such as infection at the intended injection site, significant Anti-coagulation , Allergy or Hypersensitivity to local anesthetic medications, or disproportionate risk in the event of a local anesthetic toxic reaction ( Seizure ) such as Gastric Aspiration in a patient who has not adequately fasted,

    • AND

  • There will not be a need to perform a Neurologic Examination immediately following the surgical procedure,

    • AND

  • Patient prefers this technique over other available and reasonable approaches.



INJURIES

Brachial plexus avulsion is a common neurologic injury from trauma (such as being hit by a car). The brachial plexus is susceptible to injuries that produce abduction of the thoracic limb from the body wall or a direct blow to the lateral surface of the Scapula . The cardinal signs of brachial plexus avulsion are a weakness in the arm,diminished reflexes and corresponding sensory deficits. The nerve roots are stretched or torn from their origin by this trauma, since the meningeal coverings of the nerve roots are thinner than those in the peripheral nerve. The Epineurium of the peripheral nerve is contiguous with the dural mater, providing extra support to the peripheral nerves. In cases where the nerve roots have been torn, recovery is unlikely without new experimental surgical techniques.
The diagnosis may be confirmed by an EMG examination in 5-7 days. The evidence of denervation will be evident. If there is no nerve conduction 72 hours after the injury, then avulsion is most likely.


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