Ddx: Radiculopathy, Plexopathy, Neuropathy

Question 1

Describe a motor neuron lesion presentation

Answer 1

• Cranial nerve/spinal motor neurons
• Peripheral nerve injury
• Weak/absent voluntary movements
• Ipsilateral paresis/paraylsis
• Neurogenic atrophy, wasting
• Decreased/absent reflexes
• Decreased/absent tone

Question 2

Where do the spinal nerve roots exit throughout the spine

Answer 2

• C1-7 nerve roots exit above their corresponding vertebrae
• All other spinal nerve roots exit below the pedicle of the corresponding vertebrae

Question 3

What information do afferent axons (sensory) carry

Answer 3

• Carry information from peripheral receptors toward the central nervous system
• Touch
• Proprioception
• Pressure
• Sharp/dull
• Temperature
• Pain

Question 4

What information do efferent axons (motor) carry

Answer 4

• Carry information away from the central nervous system
• Motor commands from the central nervous system to skeletal muscles

Question 5

What do the different layers of a peripheral nerve inclose

Answer 5

• Epineurion: nerve trunk
• Perineurium: separates fascicles
• Endoneurium: separates axons; sensory, motor, & autonomic

Question 6

Do peripheral nerves possess a high or low degree of resistance to ischemia

Answer 6

• High

Question 7

What is the order/degreres of peripheral nerve lesions

Answer 7

• Neuropraxia: mildest form; transient conduction block
• Axonotmesis: disruption of axon, Schwann cells/endo/perineurium intact, Wallerian degeneration
• Neurotmesis: most severe, complete nerve division, Wallerian degeneration, all structures are damaged

Question 8

What nerve roots and muscle innervations does the Axillary nerve include

Answer 8

• Nerve roots C5/C6
• Innervates Deltoid and Teres Minor
• Most likely injured in axilla due to shoulder dislocation, proximal humerus fx, or improper use of axillary crutches

Question 9

What nerve roots and muscle innervations does the Radial nerve include

Answer 9

• Nerve roots C5, C6, C7, C8, T1
• Innervates triceps, brachioradialis, supinator, wrist/finger extensors
• Common injury is “Saturday night palsy” or “Crutch palsy” results in wrist drop

Question 10

What nerve roots and muscle innervations does the musculocutaneous nerve include

Answer 10

• Nerve roots C5, C6, C7
• Innervates biceps, coracobrachialis, brachialis
• May be injured with humerus fx

Question 11

What nerve roots and muscle innervations does the Median nerve include

Answer 11

• Nerve roots C5, C6, C7, C8, T1
• Innervates flexor carpi radialis, pronator teres, palmaris longus, flexor digitorum superficialis and profundus, flexor pollicis longus, abductor pollicis brevis, flexor pollicis brevis, opponens pollicis brevis, lumbrical muscles of the index and middle fingers

Question 12

What nerve roots and muscle innervations does the Ulnar nerve include

Answer 12

• Nerve roots C7, C8, T1
• Innervates flexor carpi ulnaris, flexor digitorum profundus, adductor pollicis, abductor digiti V, opponens digiti V, flexor digiti brevis V, interosseus dorsal and palmar, lumbrical muscles of the fourth and little fingers