Branches from the Roots of brachial plexus                                                              

• Dorsal Scapular Nerve (C5):
  • * Pierces the scalenus medius muscle to reach the posterior cervical triangle.
  • * Supplies rhomboid minor and major muscles.
  • * Responsible for retraction of the shoulder girdle, giving a branch to levator scapulae.

• Long Thoracic Nerve (C5–C7):
  • * Descends behind the brachial plexus and runs on the external surface of the serratus anterior muscle.
  • * Supplies serratus anterior muscle.
  • * Responsible for overhead abduction.
  • * Damage to it causes winging of the scapula.                                                                                                                                               

Branches From the Upper Trunk of brachial plexus                                                              

• Suprascapular Nerve (C5–C6):
  • * Runs laterally across the posterior cervical triangle.
  • * Passes through the scapular notch under the superior transverse scapular ligament.
  • * Supplies the supraspinatus muscle and the shoulder joint. It then descends through the notch of the scapular neck to innervate the infraspinatus muscle.

• Nerve to Subclavius (C5):
  • * Descends in front of the brachial plexus and the subclavian artery, behind the clavicle to reach the subclavius muscle.
  • * Innervates the sternoclavicular joint.
  • * Usually gives accessory phrenic nerve (C5), which enters the thorax to join the phrenic nerve.                                              

Branches From the Lateral Cord of Brachial Plexus                                                                 

• Lateral Pectoral Nerve (C5–C7):
  • * Innervates the pectoralis-major muscle and the pectoralis minor muscle through a nerve loop.
  • * Pierces the costocoracoid membrane of the clavipectoral fascia.

• Musculocutaneous Nerve (C5–C7):
  • * Pierces the coracobrachialis muscle, descends between the biceps brachii and brachialis muscles.
  • * Supplies muscles of the front of the arm, including coracobrachialis, biceps brachii, and brachialis.

• Lateral root of median nerve (C5–C7):
  • * It joins the medial root of the median nerve.
  • * Median nerve is the chief nerve of the muscles of the front of the forearm and muscles of the thenar eminence.                                                                                                                                                                                                 

Branches From the Medial Cord of Brachial Plexus                                                                   

• Medial Pectoral Nerve (C8–T1):
  • * Passes forward between the axillary artery and vein and forms a loop in front of the axillary artery with the lateral pectoral nerve.
  • * Supplies the pectoralis minor muscle and reaches the overlying pectoralis major muscle.

• Medial Brachial Cutaneous Nerve (C8–T1):
  • * It is a small branch of the medial cord of the brachial plexus.
  • * May communicate with the intercostobrachial nerve, which arises as a lateral branch of the second intercostal nerve.
  • * It innervates the skin over the lower medial side of the arm.

• Medial Antebrachial Cutaneous Nerve (C8–T1):
  • * Runs between the axillary artery and vein and then runs medial to the brachial artery.
  • * Innervates the skin on the medial side of the forearm.

• Ulnar Nerve (C7–T1):
  • * Runs down the medial aspect of the arm but does not branch in the brachium.                                                                                 

Branches From the Medial and Lateral Cords of Brachial plexus                                                

• Median Nerve (C5–T1):
  • * It is formed as a combination from both the medial and lateral cords.
  • * Runs down the anteromedial aspect of the arm but does not branch in the brachium.                                                                         

Branches From the Posterior Cord of brachial plexus

• Upper Subscapular Nerve (C5–C6):
  • * Innervates the upper portion of the subscapularis muscle.

• Thoracodorsal Nerve (C7–C8):
  • * Runs behind the axillary artery and accompanies the thoracodorsal artery to enter the latissimus dorsi muscle.

• Lower Subscapular Nerve (C5–C6):
  • * Innervates the lower part of the subscapularis and teres major muscles.
  • * Runs downward behind the subscapular vessels to the teres major muscle.

• Axillary Nerve (C5–C6):
  • * Passes posteriorly through the quadrangular space accompanied by the posterior circumflex humeral artery and winds around the surgical neck of the humerus.
  • * Innervates the deltoid and teres minor muscles and gives rise to the lateral brachial cutaneous nerve.

• Radial Nerve (C5–T1):
  • * The largest branch of the brachial plexus.
  • * Occupies the musculospiral groove on the back of the humerus with the profunda brachii artery.