FORMATION & RELATIONS OF BRACHIAL PLEXUS
CUTANEOUS SUPPLY\ DERMATOME OF UPPER LIMB
LEARNING OBJECTIVES
At the end of this lecture students should be able to understand:
 Mention formation of brachial plexus (roots, trunk, division, and cords)
 Discuss the relation of brachial plexus also in connection to clavicle (Supra,
retro, infra clavicular parts
 Enumerate the branches arising the different cords
 Able to draw the brachial plexus
 Describe cutaneous supply of arm
BRACHIAL PLEXUS
• Plexus- is a network of nerves
• Brachial plexus-is a network of nerves found in the neck and axilla
• Formed by ventral rami of C5- C8 AND T1 ( there may be contributions
from C4, T2)
• Gives rise to nerves that supply the upper limb
FORMATION
• ROOTS Ventral Rami of :
– C5
– C6
– C7
– C8
– T1
• TRUNKS– UPPER
– MIDDLE
– LOWER
• DIVISONS
– ANTERIOR
– POSTERIOR
• CORDS
– MEDIAL
– LATERAL
– POSTERIOR
Formation of Trunks and Divisions
• C5 accepts contribution from C4 and then unites with C6 to form the upper
trunk.
• C7 will continue as the middle trunk.
• T1 accepts contribution From T2 and then unites with C8 to form the lower
trunk.
• The trunks desend laterally above the clavicle and bifurcate into anterior and
posterior division
FORMATION OF CORDS
• The anterior division of the upper trunk and middle trunk will unite to form
the lateral cord.
• The anterior division of the lower trunk continues as the medial cord.
• The posterior divisions of all the trunks will unite to form the posterior cord.
RELATIONS OF THE BRACHIAL PLEXUS
• Brachial plexus lies at the posterior triangle of the neck between the angle
formed by the clavicle and the stenocleidomastoid muscle.
• Found to emerge between the scalenus anterior and scalenus medius
muscles.
• It is covered by the skin, deep fascia, and platysma muscle
• It is also crossed by suprascapular nerve, external jugular vein, and inferior
belly of Omohyoid muscle
RELATIONS OF THE BRACHIAL PLEXUS IN THE AXILLA
• The cords of the brachial plexus derived their names based on their
relationship with the 2nd part of the axillary artery
• The lateral cord and posterior cord lie
– laterally to the 1st part of axillary artery
– The medial cord lies posterior to it.
• Below the pectoralis minor
– the lateral cord lies lateral of the 2nd part of the axillary artery
– posterior cord lies posteriorly
– The medial cord lies medially to the 2nd part of axillary artery.
• Below the pectoralis minor the cords gives their terminal branches
BRANCHES OF BRACHIAL PLEXUS
• BRANCHES FROM THE ROOT
1. Long thoracic nerve (C5,C6,C7).
2. Dorsal scapular nerve (C5).
3. Nerve to subclavius (C5, C6).
• BRANCH FROM THE TRUNK
1. Suprascapular Nerve.
• BRANCHES FROM THE LATERAL CORD
1. Lateral pectoral Nerve. ((C5, C6).
2. Musculocutaneous – (C5,C6, C7)
3. Lateral root of median nerve (C5, C6, C7).
• BRANCHES FROM THE MEDIAL CORD
1. Medial pectoral nerve
2. Medial cutaneous nerve of arm
3. Medial cutaneous nerve of forearm
4. Ulnar nerve
5. Medial root of median nerve
• POSTERIOR CORD BRANCHES
1. Axillary nerve (C5, C6)
2. Upper subscapular nerve (C5,C6)
3. Thoracodorsal nerve (C7,C8).
4. ower subscapular nerve (C5,C6)
5. Radial nerve (C5-T1).
IMPORTANT NERVES AND AREA OF SUPPLY
1) MEDIAN NERVE ( Formed by both medial and lateral cord)
• A) supplies all the flexors of the forearm( except flexor carpi ulnaris and
medial half of flexor digitorum profundus)
• B) intrinsic muscles in the lateral palm including thenar eminence)
2) ULNAR NERVE
• Supplies the medial half of flexor digitorum profundus and the flexor carpi
ulnaris
• B) supplies most of the intrinsic muscles of the hand including the
hypothenar eminence, and skin on the medial side of the hand
• Clinical application
• Injury to median nerve-” apes hand”
• Injury to ulnar nerve-” claw hand
3) MUSCULOCUTANEOUS NERVE
Supplies the biceps, coracobrachialis and brachialis
4) AXILLARY NERVE
- Supplies the deltoid and teres minor muscle
- Supplies the shoulder joint
5) RADIAL NERVE
- Supplies the triceps
- Supplies the brachioradialis
- Supplies most of the extensors of the forearm
- * injury results in “ wrist drop”
Cutaneous innervations of Upper Limb
Nerves of Brachial Plexus Supplying Upper limb
APPLIED ANATOMY OF THE BRACHIAL PLEXUS -ERB’S PARALYSIS
• This is the paralysis that occurs as a result of damage to the upper trunk of
the brachial plexus
• a result of accidental fall or birth injury
• results in damage to the nerves that
have root value of C5 and C6 which
include:
· Suprascapular nerve
· Nerve to subclavius
· Lateral pectoral nerve
· Axillary nerve
· Musculocutaneous nerve
• The arm is placed in an adducted position and medially rotated, the forearm
pronated and the palm facing backwards presenting the classical waiters tip
position.
ERB’S PARALYSIS
1. Loss of abduction of the arm due to the damage to
the suprascapular nerve which supply the
supraspinatus muscle and the axillary nerve which
supply the deltoid muscle.
2. The arm is medially rotated due to paralysis of the
lateral rotator muscles of the arm which include
the teres minor supplied by the axillary nerve and
the infraspinatus muscle supplied by the
suprascapular nerve.
3. Loss of flexion at the elbow joint due to paralysis
of the biceps brachi muscle as a result of damage
to the musculocutaneous nerve.
4. Forearm is pronated due to the unopposed action of
pronator teres muscle as a result of paralysis of the
biceps.
• Injury to the lower roots, C8 and T1, results in
Klumpke's Palsy.
• The ulnar and median nerves affected
• paralysis of all of the intrinsic muscles of hand
• Claw hand due to hyperextension of metacarpophalangeal joints and flexion
of digits by forearm flexors unopposed by interossei.
• Ulnar flexors of wrist and fingers are involved along
with cutaneous anaesthesia and analgesia along the
ulnar border.