MEDIAN NERVE

NERVE ROOTS– C6 to T1 (May contain C5)

Motor functions

• Innervates flexor muscles in the anterior compartment of forearm

• Supplies innervation to thenar muscles and lateral 2 lumbricals in hand

Sensory functions

• Innervates the lateral part of palm through the palmar cutaneous branch

• Innervates the lateral 3 1/2 fingers on the palmar surface through digital cutaneous branch

Median nerve injury

• Decreased sensation in the palm over the radial 3 ½ digits

• Unable to abduct thumb against resistance. Inability to touch thumb to other fingers

• Weak forearm pronation

 

ULNAR NERVE

NERVE ROOTS– C8 to T1

Motor function

 

• Innervates the muscles of the hand ( apart from thenar muscles and 2 lateral lumbricals), flexor carpi ulnaris and medial half of flexor digitorum profundus

Sensory function

• Medial surfaces of medial 1 ½ fingers and palm area.

Ulnar nerve injury

• Decreased sensation in the palmar and dorsal 1 ½ digits (Little finger)

• Decreased abduction and adduction

• May have decreased flexion at distal interphalangeal joints of the little and ring fingers

 

RADIAL NERVE

NERVE ROOTS– C5 to T1

Motor function

• Innervates triceps and majority of the extensor muscles of the forearm

Sensory branch

• Innervates most of the skin of the posterior side of forearm

• Supplies the dorsal surface of the lateral side of palm

• Supplies dorsal surface of lateral 3 ½ digits of he hand

Radial nerve injury

• Decreased sensation on dorsum first web space

• The weakness of extension at the distal interphalangeal joint of the thumb, and of the wrist and finger extensors.

 

MUSCULOCUTANEOUS NERVE

• Weak flexion at the elbow.

 

CIRCUMFLEX NERVE

• Weak abduction at the shoulder.

 

DIGITAL NERVE INJURY

• Decreased sensation along radial or ulnar half of digit distally

• Some sensation may be preserved

 

BRACHIAL PLEXUS INJURY

• Various combinations of lesions within the median, ulnar, radial, musculocutaneous, and circumflex nerve territories.

 

OTHER INJURIES

Superficial flexor muscles

• Unable to flex Proximal interphalangeal joints when holding the fingers straight

Deep flexor muscles

• Unable to flex Distal interphalangeal joint

Extensor tendon injury

• Complete division prevents extension (Mallet deformity)

• Central deformity causes the ‘Boutonniere deformity’