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Structure and Function > Brachial Plexus and Upper Limb Nerve Injury > Flashcards

Brachial Plexus and Upper Limb Nerve Injury Flashcards

1
Q

Brachial Plexus

A
  • Brachial plexus
    • Nerve plexus is a network of nerve fibers that arise from multiple sources
    • Nerve supply to upper limbs > sensory and motor innervation
    • Neck > axilla = sorted anterior and posterior > cords
    • Brachial plexus arises from anterior rami of C5 C6 C7 C8 T1
    • Individual nerves contain fibers from multiple spinal cord levels
      • Ie radial nerve has fibers from C5 C6 C7 C8
    • Collateral nerves (proximal muscles of shoulder and axillary walls)
      • Posterior cord > 3 subscapular nerves = muscles of posterior wall of axilla
      • Lateral and medial cords > lateral and medial pectoral nerves > muscles of anterior wall of the axilla
      • Long thoracic nerve > muscle of the medial wall of the axilla
      • Dorsal scapular nerve > shoulder girdle
      • Suprascapular nerves > shoulder girdle
    • Nerves:
      • Musculocutaneous nerve (anterior)
        • All muscles of the anterior arm
      • Median nerve (anterior)
        • Muscles of the anterior forearm (except 1.5 by ulnar nerve)
      • Ulnar nerve (anterior)
        • Muscles of anterior hand (rest by median nerve)
      • Radial nerve (posterior)
        • All muscles of the posterior arm and forearm
        • There are NO posterior hand muscles
      • Axillary nerve (posterior)
        • Deltoid muscle
        • Teres minor
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2
Q

Musculocutaneous Nerve

MARMU

A

Musculocutaneous nerve (anterior)

  • C5-C7
  • All muscles of the anterior arm
    • Biceps brachii
    • Brachialis
    • Corachobrachialis
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3
Q

Axillary Nerve

MARMU

A

Axillary nerve (posterior)

  • C5-C6
    • Deltoid muscle
    • Teres minor
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4
Q

Radial Nerve

MARMU

A

Radial nerve (posterior)

  • C5-C8
  • All muscles of the posterior arm and forearm
  • There are NO posterior hand muscles
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5
Q

Median Nerve

MARMU

A

Median nerve (anterior)

  • C6-T1
  • Muscles of the anterior forearm (except 1.5 by ulnar nerve)
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6
Q

Ulnar Nerve

MARMU

A

Ulnar Nerve

  • C8-T1
  • Flexor carpi ulnaris
  • Muscles of anterior hand (rest by median nerve)
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7
Q

Dorsal Scapular Nerve

Collateral Nerve

A
  • C5
  • Rhomboids
  • Levator scapulae
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8
Q

Suprascapular Nerve

Collateral Nerve

A
  • C5-C6
  • Supraspinatus
  • Infraspinatus
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9
Q

Lateral Pectoral Nerve

Collateral Nerve

A
  • C5-C7
  • Pectoralis major
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10
Q

Lower Subscapular Nerve

Collateral Nerve

A
  • C5-C6
  • Teres major
  • Subscapularis
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11
Q

Thoracodorsal Nerve

Collateral Nerve

A
  • C5-C7? C6-c8?
  • Latissmus dorsi
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12
Q

Upper Subscapular Nerve

Collateral Nerve

A
  • C5-C6
  • Subscapularis
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13
Q

Medial Pectoral Nerve

Collateral Nerve

A
  • C8-T1
  • Pectoralis minor
  • Pectoralis major
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14
Q
A
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15
Q

Nerve Regeneration

A
  • Peripheral nerve axon damage but cell body intact > can regenerate if have a pathway
  • Regeneration more likely with compression than laceration because of pathway
  • PNS neuron pathway = Schwann cells and endoneurium
  • Regeneration = 1cm per week after a 2 week delay
    • Proximal de-enervated will gain function before distal
    • Example
      • Median nerve lesion at elbow > forearm regain function before hand
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16
Q

Upper Trunk Injury

C5-C6

A
  • C5-C6 innervates
    • Motor: shoulder
    • Sensory: lateral arm, forearm, hand
  • Erb’s Palsy
    • Cx: Separation of shoulder from neck
      • Birth injury
      • Motor cycle injury
    • Proximal limb affected
      • Shoulder
        • Abductor, flexor, external rotator
      • Axillary walls
      • Forearm
        • Supinator
    • S/S
      • Shoulder is adducted, extended and internally rotated
      • Forearm is pronated
        • “waiter’s tip” sign
      • Sensory loss along lateral distal arm and proximal forearm
        • C5-C6 dermatomes
17
Q

Lower Trunk Injuries

C8-T1

A
  • C8-T1
    • Innervates:
      • Motor: intrinsic muscles of the hand
      • Sensory: medial forearm and arm
  • Klumpke’s Palsy
    • Cx: Stretch or compress lower trunk vis upward traction or “thoracic outlet” (cervical rib) compression
  • Distal limb muscles affected
    • Intrinsic hand muscles
      • Thenar muscles
      • Hypothenar muscles
      • Interossei
    • S/S
      • Digits 2-5 clawing
      • Loss of abduction/adduction in fingers
      • Sensory loss along medial side of distal arm and proximal forearm
        • C8-T1 dermatomes)
18
Q

Axillary Nerve Injury

A
  • Innervates:
    • Motor: deltoid, teres minor
    • Sensory: skin on deltoid
  • Cx:
    • Fracture of surgical neck of humerus
    • Glenohumeral dislocation
  • S/S
    • De-enervation of the deltoid
      • Loss of shoulder abduction
      • Deltoid atrophy
    • Loss of teres minor okay
      • Other strong lateral rotators > infraspinatus
    • Sensory loss on skin overlying the deltoid
19
Q

Radial Nerve injury

A
  • Innervates:
    • Motor: triceps brachii, extensor muscles of posterior compartment
    • Sensory: posterior arm/forearm, radial posterior-lateral hand
  • Cx:
    • Fracture of the midshaft of the humerus
    • Fracture/dislocation of the head of the radius
    • Glenohumeral dislocation
    • Upward pressure in the floor of the axilla
      • “Saturday night palsy” or “crutch injury
    • Laceration/compression at dorsum of wrist
      • Handcuffs too tight > sensory loss
  • S/S
    • Wrist drop > inability to exten wrist
    • Cutaneous sensory loss at dorsal, radial hand
    • More proximal injury > greater motor and sensory loss
    • Do not do a digit test
20
Q

Median Nerve Injury

A
  • Innervates:
    • Motor: anterior forearm (flexors), all thenar muscles, 2 lateral lumbricals of index and middle finger (LLOAF)
    • Sensory: 3.5 fingers on palmar surface
  • Cx:
    • Cubital fossa trauma
      • Supracondylar (of humerus) fracture
      • Elbow dislocation
    • Wrist trauma
      • Laceration
    • Compression in the carpal tunnel
    • Compression through the pronator teres (“entrapment”)
  • S/S
    • Thenar atrophy
    • Loss of opposition
    • Unopposed thumb (ape-hand)
    • Clawing of digits 2-3
      • Lumbrical muscles
    • If distal injury near wrist > thumb flexion and abduction may be possible
      • Flexor pollicis longus
      • Abductor pollicis longus
    • If proximal injury
      • Ulnar deviation of hand when wrist flexed
        • Flexor carpi radialis paralyzed
      • Loss of flexion at digits 1-3 “Sign of Benediction”
        • Flexor pollicis longus
        • Flexor polliics brevis
        • Flexor digitorum superficialis
        • Radial half of flexor digitorum profundus
    • Sensory loss of lateral palmar surface of hand and palmer surfaces of digits 1-3
    • Wrist flexion > nerve compression > carpal tunnel compression (common)
21
Q

Ulnar Nerve Injury

A
  • Innervates:
    • Motor: except thenar and 2 lateral lumbricals (median nerve), flexi carpi ulnaris, medial half of flexor digitorum profundus
    • Sensory: anterior and posterior of 1.5 fingers and palm area
  • Cx:
    • Trauma at the medial epicondyle of the humerus
    • Trauma at the heel of the hand
  • S/S
    • Loss of abduction/adduction of digits 2-5
      • Interosseous muscles
    • Interossei wasting
    • Clawing of Digts 4-5
      • Lumbricals paralyzed
    • Proximal injury
      • Radial deviation of hand when wrist flexed
        • Paralysis of flexor carpi ulnaris
      • Loss of flexion of DIP of digits 4-5
        • Flexor digitorium profundus
    • Cutaneous sensory loss on medial side of hand
22
Q

Musculocutaneous Nerve Injury

A
  • Uncommon
  • Cx: penetrating wound (knife, bullet)
  • S/S
    • Loss of function of anterior arm muscles
      • Weakness of shoulder flexion
      • Extreme weakness of elbow flexion
      • Weakness of supination
    • Sensory loss to lateral side of the forearm
      • Lateral antebrachial cutaneous nerve distal to musculocutaneous nerve
23
Q

Long Thoracic Nerve Injury

A
  • Innervates
    • Motor: serratus anterior
  • Cx:
    • Trauma to the chest wall > compression of nerve against chest wall
    • Surgical injury at medial axilla during surgery (most common)
  • S/S
    • “Winging” of scapulae
      • Loss of serratus anterior muscle
        • Serratus anterior attaches medial border of scapula to chest wall
      • Limited upward rotation of scapula (by intact trapezius)
        • No scapular protraction/upward rotation
    • No cutaneous sensory loss
24
Q

Thoracodorsal Nerve Injury

A
  • Cx:
    • During axillary surgery
  • S/S
    • Weakness of shoulder extension
    • Adduction and internal rotation
      • Latissimus dorsi lost
    • Not cutaneous sensory loss
25
Q

Spinal Accessory Nerve

A
  • Cx
    • Trauma in the posterior triangle of the neck or base of skull (jugular foramen)
  • S/S
    • Shoulder drop
    • Inability to abduct/flex at shoulder
      • Loss of trapiezius muscle
    • Limited upward rotation of scapula
    • No cutaneous sensory loss

Structure and Function (15 decks)

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