Brachial Plexus Anatomy-|Roots|Trunk|Division|Cord|branches|

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Introduction: It is the network of nerves present at the junction of neck and thorax.  It supplies the muscles, joints,  skin, and blood vessels of the anterior wall  of thorax, scapular region and upper limb. It is formed by ventral divisions of C5,C6,C7,C8 and T1.

Brachial plexus:

It may be fixed by two ways

A. Prefixed:  When C4 root joins with C5. Here C4 is large T2 is often absent.
B. Postfixed: When T2 root joins with T1. Here C4 root is absent. The contribution by T1 is large.

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Brachia

Situation: Roots of brachial plexus emerge between the scalenus anterior and scalenus medius muscles.

  1. Trunks appear in the lower part of Posterior triangle of neck
  2. Division lie behind the clavicle.
  • Anterior divisions supply all the muscles present on the ventral part of thorax and upper limb.

Posterior divisions supply the muscles present on dorsal part of thorax and upper limb.
3. The cords are present  in axilla. The names of the cords are in the relation with the second part of axillary artery. The cords give branches around 3rd part of axillary artery.

Relations:

  1. Supra clavicular part: The roots and trunks of the brachial plexus lie above clavicle.
  2. Retroclavicular part: The divisions of brachial plexus lie behind the clavicle.
  3. Infra clavicular part: The cords and branches of cords lie below the clavicle.

Branches: A. The nerves arising from roots supply the muscles which bring protraction and retraction of shoulder girdle i.e

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  • Nerve to rhomboids ( dorsal scapular nerve C5)
  • Nerve to serratus anterior ( long thoracic C5,C6 & C7)

B.Trunks: a. Suprascapular nerve(C5, C6) supplies

  • Supraspinatus
  • Infraspinatus
  • Shoulder joint
  • Acromioclavicular joint
  • Scapula

b. Nerve to subclavius ( C5, C6) supplies subclavius muscle.

C. Cords: Following are the branches from respective cords.
a. Lateral : Laila love majnu ( 🗝keyword)

  • Lateral pectoral nerve
  • Lateral root of median nerve
  • Musculo cutaneous nerve
     b. Medial: The 🗝word “medial”  and the branches of the medial cord begin with the letter “M” except ulnar nerve.
  • Medial pectoral
  • Medial root of median nerve
  • Medial cutaneous nerve of arm
  • Medial cutaneous nerve of forearm
  • Ulnar nerve
     c. Posterior: ULNAR ( 🗝keyword). The letter  of the word “ulnar” give the branches of the posterior cord.
  • Upper Subscapular
  • Lower Subscapular
  • Nerve to latissimus dorsi
  • Axillary nerve
  • Radial nerv

Applied anatomy: 

  1. Horner‘s syndorme:  Its is due to involvement of sympathetic nerve, which is contributed by T1 through white rami communication.  It usually occurs due to injury at the root of brachial plexus.
  2. Erbs paralysis: Injury to upper trunk usually at the Erb’s point causes Erb’s paralysis.
  3. Klumpke’s paralysis: Injury to the lower trunk of brachial plexus.
  4. Winging of scapula: Injury to the nerve to serratus anterior
  5. Claw hand: Injury to the ulnar nerve.
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People may also ask ?
  1. What are the symptoms of brachial plexus injury?

ANS: The most common symptoms of brachial plexus include,

  • Weakness or Numbness
  • Loss of sensation
  • Pain
  • Loss of movement
     2. How do brachial plexus injuries occurs ?
ANS: Brachial plexus injuries are caused by damage to those nerves. Symptoms may include a lack of muscle control in the arm, wrist and hand, limp or paralyzed arm and lack of feeling sensation in the arm and hand. brachial plexus occus as results of shoulder trauma, tumors or inflammation.
     3. Can brachial plexus injury heal on its own ?
ANS: Mild brachial plexus injuries results in tingling and weakness in the arm. This will generally go away on its own. In these type of  cases, it is very important to determine whether the injury will recover with times ,or  otherwise if surgery will be required in order to restore movement of the arm.

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