upper limb anatomy

Question 1

Motor: Elbow flexion (supplies biceps brachii) and supination

Sensory: Lateral part of the forearm

Isolated injury rare - usually injured as part of brachial plexus injury

Answer 1

Musculocutaneous nerve (C5-C7)

Question 2

Motor: Shoulder abduction (deltoid muscle)
Sensory: Inferior region of the deltoid muscle

Injured via Humeral neck fracture/dislocation
=> Results in flattened deltoid

Answer 2

Axillary Nerve (C5,6)

Question 3

Motor: Extension (forearm, wrist, fingers, thumb)

Sensory: Small area between the dorsal aspect of the 1st and 2nd metacarpals

Injured via Humeral midshaft fracture
Palsy results in wrist drop

Answer 3

Radial Nerve (C5-C8)

Question 4

Motor: Lateral two lumbricals, Opponens pollis, Abductor pollis brevis, Flexor pollis brevis
Sensory: Palmar aspect of lateral 3½ fingers

injured via Wrist lesion → carpal tunnel syndrome

Answer 4

Median nerve (C6, C8, T1)

Question 5

motor: Intrinsic hand muscles except those innervated by median. Wrist flexion
Sensory: Medial 1½ fingers

Injured via Medial epicondyle fracture
Damage may result in a ‘claw hand’

Answer 5

Ulnar nerve (C8, T1)

Question 6

Motor: Serratus anterior
Sensory: nil

Injured during sport e.g. following a blow to the ribs.
Also possible complication of mastectomy
Damage results in a winged scapula

Answer 6

Long thoracic nerve (C5-C7)

Question 7

Damage of the upper trunk of the brachial plexus (C5,C6)
- secondary to shoulder dystocia during birth
- arm hangs by the side and is internally rotated, elbow extended

Answer 7

Erb-Duchenne palsy

Question 8

Damage of the lower trunk of the brachial plexus (C8, T1)
- secondary to shoulder dystocia during birth.
- Also may be caused by a sudden upward jerk of the hand
- Associated with Horner’s syndrome

Answer 8

Klumpke injury