The ventral rami of C5, C6, C7, C8, and T1.
In the neck between the scaleneus anterior and medius muscles.
In the posterior triangle of the neck.
Each trunk divides into anterior and posterior divisions behind the middle third of the clavicle.
The flexor compartment of the upper limb.
The extensor compartment of the upper limb.
The anterior division of the upper and middle trunk unite to form the lateral cord.
Injury to the long thoracic nerve, especially when a person pushes against a wall with resistance.
Complete paralysis of the upper limb.
In the post-fixed type, the plexus is one spinal segment lower than usual, with the superior root being C6 and the inferior root being T2.
Injury to the superior parts of the brachial plexus can lead to weakness or paralysis of the shoulder and arm muscles, resulting in conditions such as Erb's Palsy.
Erb's paralysis is an injury at Erb's point that stretches or tears the upper part of the brachial plexus.
The injury occurs at Erb's point, where six nerves meet, affecting the upper trunk.
The characteristic posture is called Waiter's tip or Porter's tip.
It leads to claw hand, which is associated with lower trunk injury or Klumpke’s paralysis.
The cords lie in the axilla related to the 1st and 2nd part of the axillary artery.
An axillary nerve injury results in the loss of abduction of the arm above 15 degrees.
The Median and Ulnar nerves innervate the anterior aspect of the forearm (flexors).
The Median and Ulnar nerves are responsible for the innervation of the palm of the hand.
The Radial nerve innervates the posterior aspect of the arm and forearm.
In the pre-fixed type, the plexus is one spinal segment higher than usual, with the superior root being C4 and the inferior root being C8.
Brachial plexus blocks provide regional anesthesia as an alternative to general anesthesia for surgeries of the shoulder, arm, forearm, wrist, and hand.
Nerve to serratus anterior or long thoracic nerve (C5,6,7)
The posterior divisions unite to form the posterior cord.
Median and Ulnar nerves
It stretches the lower trunk, potentially leading to injury.
Their opponents, which produce opposite actions, are supplied by spinal segments in numerical sequence. For example, the flexor of the elbow is supplied by C5, C6, while the extensor of the elbow is supplied by C7, C8.
Techniques include interscalene block on the neck, supraclavicular block above the midpoint of the clavicle, infraclavicular block below the clavicle, and axillary block in the axilla.
The anterior division of the lower trunk continues as the medial cord.
Median and Ulnar nerves
A posterior cord injury, often due to poor fitting crutches or pressure, leads to 'Saturday night palsy' which involves the radial nerve and results in 'wrist drop' with a flexed elbow.
Most muscles are supplied by one or two spinal segments.
1. Upper subscapular nerve (C5,6) 2. Lower subscapular nerve (C5,6) 3. Thoraco-dorsal or Nerve to latissimus dorsi (C6,7,8) 4. Axillary nerve (C5,6) 5. Radial nerve (C5,6,7,8 & T1)
Injury to the inferior parts of the brachial plexus can result in weakness or paralysis of the hand and wrist muscles, leading to conditions such as Klumpke's Palsy.
RADIAL
Musculocutaneous nerve
RADIAL
1. Medial pectoral nerve (C8 & T1) 2. Medial cutaneous nerve of arm (T1) 3. Medial cutaneous nerve of forearm (C8,T1) 4. Medial root of median nerve (C8,T1) 5. Ulnar nerve (C8, T1)
The upper limbs rotate 90 degrees laterally, making the ventral surface anterior and the preaxial border lateral.
They are innervated by the anterior branches of ventral rami spinal nerves.
D. C8 - T1
Dorsal scapular nerve (C5)
It can stretch or tear the lower trunk, causing paralysis of small muscles of the hand.
Suprascapular nerve (C5 & 6)
A thoracodorsal nerve injury causes paralysis of the Latissimus dorsi, making it impossible for the person to pull up the trunk to arm level.
The Musculocutaneous nerve innervates the anterior aspect of the arm (flexors).
They are supplied by the same spinal segment, for example, the flexors of the shoulder joint (Pectoralis major, Biceps, and Coracobrachialis) are supplied by C5, C6, C7.
Joints distal in a limb are supplied by lower segments of the spinal cord, for example, the shoulder joint by C5, C6 and the elbow joint by C7, C8.
An increase in the angle between the neck and shoulder stretches the upper trunk, which can lead to injury.
Nerve to subclavius (C5 & 6)
The brachial plexus is formed by the union of the ventral rami of C5 to C8 and T1.
1. Lateral pectoral nerve (C5,6,7) 2. Lateral root of median nerve (C6&7) 3. Musculo-cutaneous nerve (C5,6,7)
Muscular elements are formed by somatic mesoderm which invades the limb bud.
Upper trunk injury can result from excessive separation of the neck and shoulder during delivery, carrying heavy weights on the shoulder, or high-speed motorcycle accidents.
The ventral side contains flexors and pronators of the upper limb.
The dorsal side contains extensors and supinators of the upper limb.
They are innervated by the posterior branches of ventral rami of spinal nerves.
