Nerves of the Arm
The nerves of the arm originate from spinal nerves C5-8 and T1.
Helpful PDF for memorizing the brachial plexus
Sensory Patterns (Dermatomes) of the Arm
Nerve Roots
C5
Motor:
- biceps flexion - C5, 6: musculocutaneous nerve
- deltoid - C5, 6: axillary nerve
Reflex:
- biceps
Sensation:
- lateral arm, above deltoid - axillary nerve
C6
Motor:
- biceps flexion - C5-C6 musculocutaneous nerve
- wrist extensors - C6-C7 radial nerve
Reflex:
- brachioradialis
- biceps
Sensation:
lateral forearm, thumb, index, half of middle finger - remember by making a "6" with these fingers
C7
Motor:
- triceps: C6,7,8 - radial nerve
- finger extension: C7 - radial nerve
- wrist flexors: C7 - median and ulnar nerves
- pronator teres: C6, 7 - median nerve
Reflex:
- triceps reflex
Sensation:
- middle finger
C8
Motor:
- finger flexion -
- finger abduction - C8, T1
- finger adduction C8, T1
Reflex:
none
Sensation:
- medial forearm, ring and little finger
T1
Motor:
- finger abduction - C8, T1
- finger adduction C8, T1
Reflex:
none
Sensation:
medial upper forearm and arm
Nerves
musculocutaneous nerve
origins and path
- from C5,6,7
- travels within biceps and brachioradialis
- becomes lateral cutaneous nerve of forearm at elbow
musculature
- biceps brachii
- coracobrachialis
- brachialis
sensory
- lateral cutaneous nerve of forearm does just that
axillary nerve
origins
musculature
sensory
- superior lateral cutaneous nerve of arm - deltoid area
radial nerve
origins
musculature
- wrist extensors
sensory
- lateral dorsal hand
median nerve
origins and path:
- from C5,6,7,8T1
- travels down centre of anterior arm
musculature
- pronator teres - pronation
- wrist flexors
- flexor pollicis brevis (thenar)
sensory
- lateral palm
- palmar surface of thumb and first 2.5 fingers
ulnar nerve
origins and pathway
- from C7,8,T1
- travels behind medial epicondyle
musculature
- flexor digitorum profundus
- flexor pollicis brevis
- palmar and dorsal interosseus muscles (abducsion/adduction)
sensory
- medial hand, with pinkie and 1/2 of ring finger