Brachial Plexus
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1. The brachial plexus forms in the posterior cervical region from nerve roots C5-T1 and provides motor and sensory innervation to the upper limb. 2. Individual nerves of the brachial plexus have specific courses and functions - for example, the radial nerve runs in the radial groove of the humerus and innervates muscles for forearm supination and wrist/finger extension. 3. Brachial plexus injuries can occur from trauma during childbirth and result in characteristic deficits depending on the level of injury, such as an upper plexus injury (C5-C7) causing weakness of arm abduction and elbow flexion ("waiter's tip" deformity
Brachial Plexus
- 1. UL: Brachial Plexus Lecture 3 Maryna Kornieieva, PhD, MD Asst. of Clinical Anatomy
- 2. Learning objectives: 1. Formation of brachial plexus 2. Relations of the BP cords to the axillary artery 3. Individual nerves of the UL: course 4. Individual nerves of the UL: function 5. Related clinical syndromes 6. General principles of distribution of nerve fibers along the UL: superior and inferior BP injuries
- 3. Formation of Brachial Plexus Middle scalene Anterior scalene Trunks Divisions Cords Roots
- 4. Supraclavicular Branches From the roots: • Dorsal scapular nerve (C5) • Long thoracic nerve (C5, 6, and 7)
- 5. Dorsal Scapular nerve (C5, C4) Course: Structures Innervated: Pierces middle scalene; descends deep to levator scapulae and rhomboids. Rhomboid major and minor
- 6. Long Thoracic nerve (C5, C6, C7) “Winged scapula” syndrome Course: Serratus Anterior Passes through cervico-axillary canal, runs inferiorly on superficial surface of serratus anterior
- 7. Supraclavicular Branches From the trunks: 1) Nerve to subclavius 2) Suprascapular nerve 1 2
- 8. Suprascapular nerve (C5, C6) Course: Structures Innervated: Passes laterally across lateral cervical region; then through the suprascapular notch inferior to superior transverse scapular ligament. Supraspinatus and infraspinatus muscles; glenohumeral (shoulder) joint.
- 9. Nerve to Subclavius (C5, C6) Course: Structures Innervated: Descends posterior to clavicle and anterior to brachial plexus and subclavian artery and vein. Subclavius and sternoclavicular joint
- 10. Nerves of Lateral Cord (C5-C7) 1. Lateral pectoral nerve 2. Musculocutaneous nerve 3. Lateral root of median nerve 1 2 3
- 11. Lateral Pectoral Nerve Course: Structures Innervated: Pierces costocoracoid membrane to reach deep surface of pectoral muscles. Primarily pectoralis major; contributes to supply of the pectoralis minor via branch to medial pectoral nerve.
- 12. Musculocutaneous Nerve Structures Innervated: “muscular” part “cutaneous” part • Exits axilla by piercing coracobrachialis; • Descends between biceps brachii and brachialis; • Continues as lateral cutaneous nerve of forearm. Course: 1. Coracobrachialis, 2. Biceps brachii, 3. Brachialis. Lateral cutaneous nerve of the forearm Injury: cannot flex elbow 12 3
- 13. Lateral and Medial Roots of Median Nerve Structures Innervated: Lateral and medial roots merge to form median nerve lateral to axillary artery; descends through arm adjacent to brachial artery, with nerve gradually crossing anterior to artery to lie medial to artery in cubital fossa Course: No structures in the arm.
- 14. Nerves of Median Cord (C8-T1) 1. Medial pectoral nerve 2. Medial cutaneous n. of arm 3. Medial cutaneous n. of forearm 4. Ulnar nerve 5. Medial root of median nerve 1 2 3 4 5
- 15. Medial Pectoral Nerve Course: Structures Innervated: Passes between axillary artery and vein; then pierces pectoralis minor and enters deep surface of pectoralis major. Pectoralis minor and sternocostal part of pectoralis major.
- 16. Ulnar Nerve Course: Descends along the posteromedial aspect of the arm; passes posterior to medial epicondyle of humerus; then descends on the ulnar aspect of the forearm to the hand. 1. Ulnar nerve 2. Median nerve 3. Medial cutaneous n. of forearm 4. Brachial artery 5. Biceps brachii 6. Triceps brachii 1 2 4 3 5 6
- 17. Medial Cutaneous Nerves of Arm (1) and Forearm (2) Course: St. In.: (1) runs along medial side of axillary and brachial veins; communicates with intercostobrachial nerve. (2) Initially runs with ulnar nerve (with which it may be confused) but pierces deep fascia with basilic vein and enters subcutaneous tissue, dividing into anterior and posterior branches. (1) Skin of medial side of arm, as far distal as medial epicondyle of humerus and olecranon of ulna. (2) Skin of medial side of forearm, as far distal as wrist. Intercostobrachial n. 1 1 2
- 18. Nerves of Posterior Cord (C5-T1) 1. Upper subscapular nerves 2. Lower subscapular nerves 3. Thoracodorsal nerve 4. Axillary nerve 5. Radial nerve 1 2 3 4 5
- 19. Upper (1) and Lower (2) Subscapular Nerves (C5, C6) Course: Pass posteriorly (1) and inferiorly (2) to enter subscapularis m. Subscapularis (1,2) + Teres major (2)Structures Innervated: 1 2
- 20. Thoracodorsal Nerve (C6, C7, C8) Course: Structures Innervated:Arises between the upper and lower subscapular nerves and runs inferolaterally along the posterior axillary wall to the upper part of the latissimus dorsi. Latissimus dorsi
- 21. Axillary Nerve (C5, C6) Course: Structures Innervated: Exits axillary cavity passing through quadrangular space with posterior circumflex humeral artery; gives rise to superior lateral brachial cutaneous nerve; then winds around surgical neck of humerus deep to deltoid. GH joint; teres minor and deltoid muscles; skin of superolateral arm. Injury: loss of abduction 15-90◦
- 22. Radial Nerve (C5-T1) Course: Common places of injury: 1) Radial (spiral) groove of the humerus 2) Entering the posterior compartment of forearm b/w 2 heads of supunator runs posterior to the spiral/radial groove of the humerus
- 23. Brachial Plexus Injuries C5 – T1 C5 – C7 C8 – T1 Proximal part of the upper limb (i.e., shoulder and arm) Distal part of the upper limb (i.e., forearm and hand) Upper brachial plexus palsy (Erb or Erb– Duchenne) Mechanism of trauma: forced shoulder abduction Mechanism of trauma: forced lateral flexion of the neck, forceps delivery. Lower brachial plexus palsy (Klumpke)
- 24. Upper BP palsy (Erb–Duchenne) Infant with flail upper limb Shoulder dystocia during delivery. The right shoulder is impeded in the birth canal by the pubic symphysis. Sensory Deficit • Lateral aspect of upper limb Motor Deficit • Loss of arm abduction and lateral rotation • Loss of elbow flexion • Loss of forearm supination • Weakness of wrist extension “waiter’s tip” arm deformity Obstetric Brachial Plexus Palsy
- 25. Lower BP palsy (Klumpke) Obstetrics precondition: vertex presentation (i.e., the occiput is first to enter the birth canal). • All fingers are clawed; “clawed hand” deformity • A supinated forearm is due to weakened pronator quadratus. 2) Sensory loss: med. side of arm and forearm 1) Motor loss: flexor and extensors of the forearm, + intrinsic muscles of the hand. C8 - T1 ulnar, median, and radial nn. + Horner syndrome
- 26. Revision Short nerves: Long nerves: • Shoulder • Arm • Forearm • Hand 1. Median n. 2. Ulnar n. 3. Radial n.
- 27. Thank you for your attention!!!