Nerves (motor and sensory components) of the upper limb Flashcards
What are the dermatomes of the upper limb?
C4 shoulder
C5 lateral side of arm
C6 lateral side of forearm and thumb
C7 middle and ring finger
C8 medial side of hand, forearm and little finger
T1 medial side of upper forearm and arm
T2 axilla
How should the biceps deep tendon reflex be tested and what are the nerve roots?
Musculocutaneous nerve- C5 and C6.
Ask the patient to rest comfortably (sitting or lying supine), with elbow semi-flexed and hand pronated.
Place your thumb on the biceps tendon and tap briskly with the tendon hammer on the nail bed of your thumb.
If the reflex arc is intact there will be a brisk contraction of the biceps causing flexion of the forearm at the elbow joint.
Compare with that of the contralateral limb.
How should the triceps tendon reflex be tested and what are the nerve roots?
Radial nerve- C7 and C8.
Ask the patient to rest comfortably (sitting or lying supine), with elbow semi-flexed and hand pronated.
Support the elbow with one hand.
Tap the triceps tendon directly with the tendon hammer.
If the reflex arc is intact there will be a brisk contraction of the triceps causing extension of the forearm.
Compare with that of the contralateral limb.
How would you test the motor and sensory components of the axillary nerve?
Motor: innervates deltoid and teres minor muscles. Responsible for abduction of the arm at the shoulder beyond first 15 degrees. Ask patient to abduct their arm against resistance.
Sensory: innervates skin over shoulder. Test with cotton wool.
Nerve roots: C5 and C6.
How would you test the motor and sensory components of the musculocutaneous nerve?
Motor: innervates biceps brachii, brachialis, and coracobrachialis muscles. Responsible for flexion of the arm at the elbow, and supination of the forearm. Ask the patient to flex their arm at the elbow against resistance.
Sensory: lateral surface of forearm. Test with cotton wool.
Nerve roots: C5-C7.
How would you test the motor and sensory components of the radial nerve in the arm and forearm?
Motor: wrist extensors. Ask patient to extend their wrist, fingers and thumb against resistance.
Sensory: radial aspect of the dorsum of the hand, thumb, index finger, middle finger, radial half of the ring ringer proximal to the distal interphalangeal joints. Test with cotton wool at the dorsal web space between thumb and index finger.
How would you test the motor and sensory components of the ulnar nerve in the forearm and hand?
Motor: flexor carpi ulnaris, flexors of distal phalanx of ring and little fingers, all intrinsic hand muscles except the thenar group. Ask patient to abduct their fingers against resistance.
Sensory: ulnar portion of the dorsum of the hand, fifth digit, ulnar aspect of ring finger, hypothenar eminence. Test with cotton wool at the volar tip of the fifth digit.
How would you perform a basic motor examination of the hand?
Evaluation of median nerve integrity includes thumb opposition with little finger, and flexion of thumb interphalangeal (IP) joint with index finger proximal IP (PIP) joint to form an “OK” sign.
Ulnar nerve evaluation includes abduction of fingers by spreading them apart, and criss-crossing the index and third finger.
Radial nerve evaluation includes thumb extension to make a “thumbs-up” sign, dorsal wrist extension and extension of fingers at the metacarpophalangeal (MCP) joint.
How would you test the motor and sensory components of the median nerve in the forearm and hand?
Motor: muscles involving fine precision and pinch function of the hand, thenar muscles, index and middle finger lumbricals. Ask patient to touch their thumb to their fifth finger (opposition)- watch thenar muscles contract.
Sensory: thumb, index, middle and radial side of ring finger. Test with cotton wool at the volar tip of the index finger.
