Brachial Plexus Flashcards
Muscles in the anterior arm, anterior forearm, and hand that act mainly as FLEXORS are innervated by nerves that contain ANTERIOR DIVISION FIBERS
Musculocutaneous
Ulnar
Median
Lateral and Medial Pectoral Nerves
Muscles in the posterior arm and posterior forearm that act mainly as EXTENSORS are innervated by nerves that contain POSTERIOR DIVISION FIBERS
Axillary
Radial
Upper, Middle and Lower Subscapular Nerves
Branches of the brachial plexus
ROOTS
Roots:
DORSAL SCAPULAR (C5) - Rhomboids
LONG THORACIC (C5-C7) - Serratus Anterior
Branches of the brachial plexus
UPPER TRUNK
Upper trunk:
NERVE TO SUBCLAVIUS (C5 & C6)
SUPRASCAPULAR (C5 & C6)
- Supraspinatus Infraspinatus
Branches of brachial plexus
LATERAL CORD
Lateral cord:
LATERAL PECTORAL (C5-C7) - Pectoralis Major
MUSCULOCUTANEOUS (C5-C7)
- Coracobrachialis
- Biceps brachii
- Brachialis
LATERAL ROOT OF MEDIAN (C5, C6 & C7)
Branches of brachial plexus
MEDIAL CORD
Medial cord:
MEDIAL PECTORAL (C8-T1) - Pectoralis Minor
MEDIAL CUTANEOUS NERVE OF ARM (C8-T1)
MEDIAL CUTANEOUS NERVE OF FOREARM
(C8-T1)
ULNAR (C8-T1)
MEDIAL ROOT OF MEDIAN (C8-T1)
Branches of brachial plexus
POSTERIOR CORD
Posterior cord:
UPPER SUBSCAPULAR (C5 & C6) - Subscapularis
THORACODORSAL (C6, C7 & C8)
- Latissimus dorsi
LOWER SUBSCAPULAR (C5 and C6) - Teres Major
AXILLARY (C5 and C6)
- Deltoid, Teres Minor
RADIAL (C5, C6, C7, C8 and T1)
Axillary nerve
Deltoid
Teres Minor
Musculocutaneous nerve
Anterior / Flexor compartment of arm
Radial nerve
Posterior / Extensor compartment of arm and forearm
Median nerve
Anterior / flexor compartment of forearm except FCU and FDP - medial
Ulnar nerve
Intrinsic muscles of hand
Tendon reflexes:
Biceps Brachii tendon reflex
Triceps tendon reflex
Brachioradialis tendon reflex
Biceps Brachii tendon reflex
- C5 and C6; flexion of the elbow joint by tapping the biceps tendon
Triceps tendon reflex
- C6, C7 and C8; extension of the elbow joint by tapping the triceps tendon
Brachioradialis tendon reflex
- C5, C6 and C7; supination of the radioulnar joints by tapping the insertion of the brachioradialis tendon
- Results from lesion of C5 and c6 ventral rami in the superior trunk of the plexus
- PROXIMAL musculature in the upper limb is mainly affected - muscles acting at the shoulder and at the elbow will be weakened
- upper limb is held in a “WAITER’s TIP” position; arm is adducted, extended and medially rotated; forearm is probated and the carpal flexors flex the hand at the wrist
- altered sensation in lateral arm, forearm, thumb and index finger
ERB-DUCHENNE’s SYNDROME
- Result from compression if the c8 and T1 ventral rami in the inferior trunk of the plexus
- DISTAL muscles in the upper limb innervated by C8 and T1 will be affected
- altered sensation in the medial hand, ring and little finger
- weakness of the intrinsic muscles of hand - combination of an “APE hand” and a “CLAW hand”
KLUMPKE’s PARALYSIS
Most commonly injured as it courses superficial to the SERRATUS ANTERIOR on the lateral wall of the thorax
Patients cannot hold the vertebral border of the scapula flat against the back may have a “WINGING” of the vertebral border
Experience weakness in the ability to PROTRACT the scapula and difficulty in aria using arm above their head
Etiologies: thoracic surgery; Radical mastectomy; stab wounds
LONG THORACIC NERVE LESIONS
May be as a result of surgical procedures of the axilla
Patients may have difficulty in elevating the trunk and may have difficulty in using a crutch
Latissimus dorsi muscle is affected
THORACODORSAL NERVE LESIONS
May be injured as a result of a dislocation of the head of the humerus or by a fracture of thE SURGICAL NECK of the humerus
Patients may experience weakness in the ability to ABDUCT the arm and there may be altered sensation in the skin covering the DELTOID
weakness in LATERAL ROTATION because of weakness of Teres minor muscle
AXILLARY NERVE LESIONS
Uncommon
May be compressed as it passes through the Coracobrachialis muscle
Weakness in flexion of the forearm at the elbow and weakness in supination
MUSCULOCUTANEOUS NERVE LESION
As a result of a SPIRAL fracture of the MIDSHAFT of the humerus
“WRISTDROP”
Weakness in the ability to extend the hand at the wrist and a loss of extension at the MP joints of all digits
May experience pain and paresthesia in skin over the first dorsal interosseous muscle between the thumb and index finger
Supination may be weakened but not lost
Extension of the forearm is spared
RADIAL NERVE LESIONS
SUPRACONDYLAR fracture of the humerus
Compression between heads of pronator teres muscle
Altered cutaneous sensation - lateral 3 & 1/2 digits and thenar eminence
Weakness in flexion at wrist; flexion of lateral fingers and flexion of thumb
“HAND OF BENEDICTION” - index and middle fingers remain extended when attempting to flex in making a fist
MEDIAN NERVE LESION (PROXIMAL)
CARPAL TUNNEL SYNDROME
- LUNATE dislocation
Experience numbness and pain over the palmar aspects of thumb, index and middle fingers
Altered cutaneous sensation - lateral 3 &1/2 digits
“APE HAND” - weakness in OPPOSITION of thumb; remains adducted and extended
MEDIAN NERVE LESION (DISTAL)
MEDIAL EPICONDYLE fracture of the humerus
Altered cutaneous sensation - medial 1 & 1/2 digits and hypo thenar eminence
Weakness in flexion of medial fingers; flexion at wrist
ULNAR NERVE LESION (PROXIMAL)
Fracture of hook of HAMATE
altered sensation in skin of the medial aspect of the hand and digits
“CLAW HAND” - caused by weakness of the medial 2 lumbricals that flex the MP joints and extend the IP joints of the ring and little fingers
Weakness in the ability to abduct/adduct fingers (unable to hold a piece of paper between adjacent fingers)
ULNAR NERVE LESION (DISTAL)
Blood vessels of the BRACHIAL PLEXUS
Axillary artery
Brachial artery
Radial/Ulnar artery
Palmar arch
Artery that is continuation if subclavian artery
From 1st rib to TERES MAJOR
Axillary artery
Tendon of PECTORALIS MINOR divides the vessels into 3 parts
1st part
2nd part
3rd part
1st part: SUPERIOR THORACIC ARTERY (highest thoracic artery) supplies the muscles of the FIRST TWO INTERCOSTAL SPACES
2nd part: THORACOACROMIAL (pectoral, acromial, deltoid, clavicular) and LATERAL THORACIC
3rd part: SUBSCAPULAR ARTERY (largest branch); supplies subscapularis, teres major & latissimus dorsi; branches 1. thoracodorsal artery (along the thoracodorsal nerve and long thoracic nerve) supplies the anterior serratus muscle & 2. Circumflex scapular artery. ANTERIOR CIRCUMPLEX UMERAL & POSTERIOR CIRCUMPLEX HUMERAL
Veins of the Upper X
Cephalic vein –> Axillary vein
Basilic vein + Brachial vein = Axillary vein
Axillary vein –> Brachiocephalic
Posterior to styloid process of radius - ascends lateral side of Biceps brachii - reaches intraclavicular fossa - drains into axillary vein
CEPHALIC VEIN
Choice for central venous catheterization - increases in diameter and is in direct line with axillary vein
BASILIC VEIN
Between anterior & middle scalene muscles
Ventral primary rami (C5-T1)
Posterior triangle of the neck
Upper middle & lower trunks
5 major terminal branches
Musculocutaneous nerve (C5,6,7)
Axillary nerve (C5,6)
Radial nerve (C5,6,7,8,T1)
Median nerve (C5,6,7,8,T1)
Ulnar nerve (C8,T1)
Roots?
Trunks?
Divisions?
Cords?
5 roots
3 trunks
6 divisions
3 cords
