The brachial plexus is formed by the ventral rami of cervical spinal nerves C5-T1. It provides motor and sensory innervation to the upper limb. The brachial plexus has 5 roots, 3 trunks, 6 divisions, 3 cords, and 5 major branches that innervate specific muscles and skin areas of the upper limb. Injuries to different parts of the brachial plexus can result in paralysis of certain muscles and sensory loss.

2. Brachial Plexus
• It begins in the root of the neck, passes through the axilla, and runs through
the entire upper extremity
• Network of nerve fibres that supplies the skin and musculature of the upper
limb
• Provides full sensory and motor innervation to the arm
• The plexus is formed by the anterior rami (divisions) of cervical spinal
nerves C5-C8 and thoracic spinal nerve T1
• The brachial plexus is divided into five parts; roots, trunks, divisions, cords
and branches (Read That Damn Cadaver Book)

3. 5 Roots
• These are the anterior rami of spinal nerves formed from 5 roots i.e. C5, C6, C7,
C8, and T1
• These nerves pass between the anterior and medial scalene muscles to enter the
base of the neck

4. 3 Trunks
• Roots merge to form trunks in the posterior triangle of the neck
• 3 trunks are formed
 Superior trunk (C5-C6)
Spinal nerve from C5 & C6 merges to form Superior/Upper trunk
 Middle trunk (C7)
 Inferior trunk (C8-T1)
Spinal nerve from C8 & T1 merges to form Inferior/Lower trunk

5. 6 Divisions
• Trunk split into 2 branches within the posterior triangle of the neck
• One division moves anteriorly and the other posteriorly
• 3 anterior and 3 posterior nerve fibers leave the posterior triangle
and pass into the axilla
Anterior
Anterior
Anterior
Posterior
Posterior
Posterior

6. 3 Cords
• Divisions combine together to form 3 cords
• Lateral Cord is formed from Anterior division of Superior and
Middle Trunk
• Posterior Cord formed from Posterior division of Superior,
Middle and Inferior Trunk
• Medial Cord is formed from Anterior division of Inferior
Trunk

7. 5 Major Branches
• Musculocutaneous nerve
• Axillary nerve
• Median nerve
• Radial nerve
• Ulnar nerve

8. ROOTS (5) TRUNKS (3) DIVISIONS (6) CORDS (3) BRANCHES (5)
SUPERIOR
MIDDLE
INFERIOR
ANTERIOR
ANTERIOR
POSTERIOR
LATERAL (C5-C7)
POSTERIOR (C5-T1)
MEDIAL (C8-T1)
MUSCULOCUTANEOUS NERVE
MEDIAN NERVE
ULNAR NERVE

9. BRANCHES FROM ROOT AND TRUNK
LONG THORACIC NERVE (C5-C7)
DORSAL SCAPULAR NERVE (C4-C5)
SUPRASCAPULAR NERVE (C5-C6)
NERVE TO SUBCLAVIUS (C5-C6)
PHRENIC NERVE (C3-C5)

10. BRANCHES FROM ROOT AND TRUNK
Branches from root
1. Long thoracic nerve (C5-C7)
2. Phrenic nerve (C3-C5)
3. Dorsal scapular nerve (C4-C5)
Branches from the Trunk
There are two branches from the upper trunk
1. Suprascapular nerve (C5-C6)
2. Nerve to subclavius (C5-C6)

11. LATERAL PECTORAL NERVE (C5-C7)
UPPERSUBSCAPULAR NERVE
NERVE TO LATTISMUS DORSI OR
THORACO-DORSAL NERVE
LOWER SUBSCAPULAR NERVE
MEDIAL CUTANEOUS NERVE OF FOREARM
MEDIAL CUTANEOUS NERVE OF ARM
MEDIAL PECTORAL NERVE
BRANCHES FROM CORD

12. BRANCHES FROM THE CORD
Lateral cord gives off three branches
1. Musculocutaneous nerve
2. Lateral pectoral nerve
3. Lateral root of Median nerve
Posterior cord gives off five branches (ULNAR)
1. Upper subscapular nerve
2. Lower subscapular nerve
3. Nerve to latissimus dorsi or Thoracodorsal nerve
4. Axillary nerve
5. Radial nerve
Medial cord gives off five branches (MMMMU)
1. Medial pectoral nerve
2. Medial cutaneous nerve of arm
3. Medial cutaneous nerve of forearm
4. Medial root of Median nerve
5. Ulnar nerve

13. Origin Nerve Muscles
Lateral
Cord
(C5-C7)
Musculocutaneous Nerve Biceps Brachii, Brachialis, Coracobrachialis (BBC)
Lateral Pectoral Nerve Pectoralis major and Pectoralis minor
Median Nerve
(C5-T1)
Flexor of the forearm except Flexor carpi ulnaris, Thenar
muscles, 2 lateral lumbricals
Medial
Cord
(C8-T1)
Ulnar Nerve Flexor Carpi Ulnaris, flexor digitorum profundus, muscles of the
hand except the thenar and 2 lumbricals
Medial Pectoral Nerve Pectoralis major and Pectoralis minor
Medial Cutaneous Nerve Of The Arm Skin of arm
Medial Cutaneous Nerve Of The Forearm Skin of forearm
Posterior
Cord
(C5-T1)
Axillary Nerve Deltoid and Teres Minor
Radial Nerve Supinator, Extensors of the forearm, Anconeus, Triceps (SEAT)
Lower Sub Scapular Nerve Subscapularis and Teres Major
Upper Sub Scapular Nerve Subscapularis
Thoracodorsal Nerve Lattisimus Dorsi

14. Distribution of Nerve branches of Brachial Plexus
Erb’s Point
A point in upper trunk that is a meeting point of 5 nerve branches
Nerves Region supplied
Musculocutaneous nerve Anterior compartment of the arm (Flexor)
Median Flexors of forearm and intrinsic muscles of the hand
Ulnar FCU, FDP and intrinsic muscles in hand
Axillary Deltoid and Teres Minor
Radial Extensors of arm and forearm

15. Origin Nerve Muscles
Roots
C3-C5
Phrenic Nerve Diaphragm
C4-C5
Dorsal scapular
nerve
Rhomboid Major and
Minor, Levator
scapulae
C5-C7
Long Thoracic
nerve
Serratus Anterior
Upper
trunk
Nerve to
Subclavius
Subclavius muscle
Upper
trunk
Suprascapular
Nerve
Supraspinatus and
Infraspinatus muscle

16. Nerves of the Hand
 Median Nerve innervates front of index and middle finger, medial half of thumb, lateral half of ring finger and upper half
of these fingers posteriorly
 Ulnar Nerve supplies the small finger and medial half of the ring finger anteriorly and posteriorly
 Radial nerve supplies lateral half of the thumb and lower portion of the index and middle finger

17. CLINICAL ANATOMY OF BRACHIAL PLEXUS
• Site of injury
• Cause of injury
• Nerve roots involved
• Muscles paralyzed
• Deformity
• Disability
• Sensory loss
• Vasomotor changes
• Trophic changes

18. Erb’s Paralysis
Site of injury Upper Trunk or Erb’s point
Cause of
injury
Birth injury, fall on shoulder
Nerve roots
involved
C5 and C6
Muscles
paralyzed
BBC, Supraspinatus, Infrasinatus, Deltoid,
Deformity Policeman’s tip, waiter’s tip paralysis
Position of the
Hand
Arms hang by side (adducted), medially rotated,
extension at elbow, forearm is pronated
Disability Abduction and lateral rotation of arm
Flexion and Supination of forearm
Sensory loss Small area over the deltoid

19. Site of injury Lower Trunk
Cause of injury Undue abduction of the arm, Birth injury
Nerve roots
involved
C8 and T1
Muscles
paralyzed
Intrinsic muscles of the hand, flexor of wrist and fingers
Deformity Claw hand
Disability Claw hand, cutaneous anesthesia and analgesia along
medial border of forearm and hand
Horner’s
Syndrome
Ptosis, myosis, anhidrosis, enophthalmos
Vasomotor
changes
Skin is warm (due to arteriolar dilatation) and dry
(anhidrosis due to loss of sympathetic activity)
Klumpke’s Paralysis

20. Site of injury Long thoracic nerve
Cause of injury Sudden pressure on shoulder, carrying
heavy loads
Nerve roots involved C5-C7
Muscle paralyzed Serratus anterior
Deformity Winging of scapula
Disability Loss of pushing and punching action,
overhead abduction is not possible
(beyond 90°)
Winging of Scapula