Upper limb nerve injury

Question 1

How is the axillary nerve commonly damaged?

Answer 1

Shoulder dislocation (esp. anterior) 
Fractured surgical neck of humerus

Question 2

What muscles are innervated by the axillary nerve?

Answer 2

Deltoid

Teres Minor

Question 3

How is the median nerve commonly damaged?

Answer 3

Penetrating injury to medial arm/ cubital fossa or anterior wrist
Carpal Tunnel (compression)
Compression between heads of Pronator Teres

Question 4

What muscles are innervated by the median nerve?

Answer 4

Anterior forearm (except Flexor Carpi Ulnaris and Flexor Digitorum Profundus to digits 4+5)
Thenar muscles
Lumbricals to digits 2+3

Question 5

What would damage or compression of the median nerve at the wrist result in?

Answer 5

Thenar wasting
Loss of thumb opposition
Thumb placement would be laterally rotated and adducted
Digits 2+3 would lag when making fist (paralysis of lumbricals 1+2)
Sensory loss would be dependent on whether damage was just to Carpal Tunnel syndrome (palm can be spared) or distal forearm laceration (palm sensation lost)

Question 6

Why can sensation to the palm be spared in Carpal Tunnel Syndrome compared to a laceration to the distal forearm, damaging the median nerve?

Answer 6

Palmar branch of median nerve branches before Carpal Tunnel - does not pass through

Question 7

What additional features may be seen if the median nerve was damaged at the elbow (or proximal)?

Answer 7

Loss of pronation of forearm

Weak wrist flexion

Question 8

How can the ulnar nerve be damaged?

Answer 8

Medial epicondyle (fracture/ compression)
Cubital tunnel (compression)
Guyon's Canal (wrist)

Question 9

What would damage of the ulnar nerve result in?

Answer 9

Loss of most intrinsic hand muscles (except thenar eminence and lumbricals 1+2)