The radial nerve is at risk of injury at three locations in the upper limb: in the axilla, in the spiral groove of the humerus, and at the elbow. Injury in the axilla can result from pressure from a crutch and causes motor loss of triceps, wrist and finger extension, and supination as well as sensory loss in the arm and back of the forearm. Injury in the spiral groove most commonly causes motor loss of wrist and finger extension with possible sensory loss only in the hand. Radial tunnel syndrome can cause compression of the radial nerve at the elbow, resulting in loss of wrist and finger extension but no wrist drop.

1. Nerves of Upper limb & their Injuries
Dr Diwakar Kumar Shah
Assistant Professor
Department of Anatomy
Nobel Medical College Teaching Hospital

2. Introduction
• The nerve supply to the upper limb is provided by the brachial plexus.
• The five major nerves supplying the upper limb are:
• Axillary nerve.
• Musculocutaneous nerve.
• Radial nerve.
• Median nerve.
• Ulnar nerve.

3. Axillary Nerve
• The axillary nerve (C5 and C6) arises from
posterior cord of brachial plexus.
• It provides motor innervation to the deltoid
and teres minor muscles and sensory
innervation to the shoulder joint and to the
skin over the lower lateral part of the shoulder.

5. Musculoculatenous nerve
• The musculocutaneous nerve arises from lateral
cord of the brachial plexus (C5, C6, and C7).
• It provides motor innervation to the muscles on
the front of the arm and sensory innervation to
the skin of the lateral part of the forearm

7. Radial Nerve
• The radial nerve is a continuation of posterior cord of brachial plexus in the axilla.
• It is the largest nerve of the brachial plexus.
• It carries fibres from all the roots (C5, C6, C7, C8, and T1) of brachial plexus.
• In the axilla, the radial nerve lies posterior to the third part of the axillary artery and
anterior to the muscles forming the posterior wall of the axilla.
• In the axilla, it gives off the following three branches:
• Posterior cutaneous nerve of arm (which provides sensory innervation to skin on the back of the arm
up to the elbow).
• Nerve to the long head of triceps.
• Nerve to the medial head of triceps

11. • Radial nerve enters the arm at the lower border of the teres major.
• It passes between the long and medial heads of triceps to enter the lower
triangular space, through which it reaches the spiral groove along with profunda
brachii artery.
• The radial nerve in the spiral groove lies in direct contact with the humerus.

12. In the spiral groove, it gives
• Lower lateral cutaneous nerve of the arm:
• It provides sensory innervation to the skin on the lateral surface of the arm up to the elbow.
• Posterior cutaneous nerve of the forearm:
• It provides sensory innervation to the skin down the middle of the back of the forearm up to
the wrist.
• Nerve to lateral head of triceps.
• Nerve to medial head of triceps.
• Nerve to anconeus:
• It runs through the substance of medial head of triceps to reach the anconeus

13. • At the lower end of the spiral groove, the radial nerve pierces the lateral muscular
septum of the arm and enters the anterior compartment of the arm.
• It first descends between the brachialis and brachioradialis, and then between
brachialis and extensor carpi radialis longus before entering the cubital fossa.
• In the anterior compartment of arm above the lateral epicondyle, it gives off the
following three branches:
• Nerve to brachialis (small lateral part).
• Nerve to brachioradialis.
• Nerve to extensor carpi radialis longus (ECRL).
• At the level of lateral epicondyle of humerus, it terminates by dividing into superficial
and deep branches in the lateral part of the cubital fossa.

14. Deep Branch/Posterior Interosseous nerve
• In the cubital fossa it supplies two muscles, viz.
• Extensor carpi radialis brevis.
• Supinator.
• After supplying these two muscles, it passes through the substance of supinator
and enters the posterior compartment of the forearm.
• It then supplies all the extensor muscles of the forearm.
• It also gives articular branches to the distal radio-ulnar, wrist, and carpal joints.

15. Superficial branch
• It is sensory.
• It runs downwards over the supinator, pronator teres, and flexor digitorum
superficialis deep to brachioradialis.
• About one-third of the way down the forearm (at about 7 cm above wrist), it passes
posteriorly, emerging from under the tendon of brachioradialis, proximal to the styloid
process of radius.
• It then passes over the tendons of anatomical snuff-box, where it terminates as
cutaneous branches.
• The cutaneous branches provide sensory innervation to skin over the lateral part of
the dorsum of hand and dorsal surfaces of lateral 3½ digits proximal to the nail beds.

16. Injuries to radial nerve
• The radial nerve may be injured at three sites:
• In the axilla
• In the spiral groove
• At the elbow.

17. In the axilla the radial nerve may be injured by the pressure of the
upper end of crutch (crutch palsy).
Motor loss
• Loss of extension of elbow—due to paralysis of
triceps.
• Loss of extension of wrist—due to paralysis of
wrist extensors. This causes wrist drop due to
unopposed action of flexor muscles of the forearm
• Loss of extension of digits—due to paralysis of
extensor digitorum, extensor indicis, extensor
digiti minimi, and extensor pollicis longus.
• Loss of supination in extended elbow because
supinator and brachioradialis are paralyzed but
supination becomes possible in flexed elbow by
the action of biceps brachii.
Sensory Loss
• Sensory loss on small area of skin over the
posterior surface of the lower part of the arm.
• Sensory loss along narrow strip on the back of
forearm.
• Sensory loss on the lateral part of dorsum of hand
at the base of thumb and dorsal surface of lateral
3½ digits. More often, there is an isolated sensory
loss on the dorsum of hand at the base of the
thumb.

18. Injury of radial nerve in the radial/spiral groove
• In radial groove, the radial nerve may be injured due to:
• Midshaft fracture of humerus
• Inadvertently wrongly placed intramuscular injection
• Direct pressure on radial nerve by a drunkard falling asleep with his one arm over the back of the chair
(Saturday night paralysis).
• Injury to radial nerve occurs most commonly in the distal part of the groove beyond the origin of nerve
to triceps and cutaneous nerves.
• Clinical features in such cases will be as follows:
• Motor loss
• Loss of extension of the wrist and fingers.
• Wrist drop.
• Loss of supination when the arm is extended.
• Sensory loss is restricted only to a variable small area over the dorsum of hand between the first and
second metacarpals.
• Extension of the elbow is possible but may be little weak because nerves to long and lateral heads of
triceps arises in the axilla i.e., before the site of lesion.

19. Injury of radial nerve at elbow
• Radial tunnel syndrome:
• It is an entrapment neuropathy of the deep branch of radial nerve at elbow.
• The compression of radial nerve at elbow may be caused by the following four structures:
• Fibrous bands, which can tether the radial nerve to the radio-humeral joint.
• Sharp tendinous margin of extensor carpi radialis brevis.
• Leash of vessels from the radial recurrent artery.
• Arcade of Frohse, a fibro-aponeurotic proximal edge of the superficial part of the supinator muscle.
• Characteristic clinical features:
• Loss of extension of the wrist and fingers but no wrist drop.
• Pain over the extensor aspect of the forearm.