Brachial plexus
- 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