Upper limb anatomy

Anatomy · Upper limb anatomy

The information below contains selected facts which commonly appear in examinations:

Nerve	Motor	Sensory	Typical mechanism of injury & notes
Musculocutaneous nerve (C5-C7)	Elbow flexion (supplies biceps brachii) and supination	Lateral part of the forearm	Isolated injury rare - usually injured as part of brachial plexus injury
Axillary nerve (C5,C6)	Shoulder abduction (deltoid muscle)	Inferior region of the deltoid muscle	Humeral neck fracture/dislocation Results in flattened deltoid
Radial nerve (C5-C8)	Extension (forearm, wrist, fingers, thumb)	Small area between the dorsal aspect of the 1st and 2nd metacarpals	Humeral midshaft fracture Palsy results in wrist drop
Median nerve (C5-T1)	LOAF* muscles Features depend on the site of the lesion: wrist: paralysis of thenar muscles, opponens pollicis elbow: loss of pronation of forearm and weak wrist flexion	Palmar aspect of lateral 3½ fingers	Wrist lesion → carpal tunnel syndrome
Ulnar nerve (C8, T1)	Intrinsic hand muscles except LOAF* Wrist flexion	Medial 1½ fingers	Medial epicondyle fracture Damage may result in a 'claw hand'
Long thoracic nerve (C5-C7)	Serratus anterior		Often during sport e.g. following a blow to the ribs. Also possible complication of mastectomy Damage results in a winged scapula

Diagram of the brachial plexus

Erb-Duchenne palsy ('waiter's tip')

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

Klumpke injury

due to damage of the lower trunk of the brachial plexus (C8, T1)
as above, may be secondary to shoulder dystocia during birth. Also may be caused by a sudden upward jerk of the hand
associated with Horner's syndrome

*LOAF muscles

Lateral two lumbricals
Opponens pollis
Abductor pollis brevis
Flexor pollis brevis