Nerve Palsies Flashcards
Define Hilton’s Law?
Any nerve supplying a joint will also supply:
- The muscles moving that joint
- Skin over the insertion of those muscles
Example of a nerve following Hilton’s Law?
Musculocutaneous nerve supplies the anterior capsule of the elbow, as well as:
- Muscles biceps, coracobrachialis and brachialis
- Skin over these muscle insertion (lateral forearm via lateral cutaneous nerve of forearm)
Infant presents with the classic “Waiters Tip” position, what is this position?
Shoulder adducted and Internally rotated
Elbow extended and pronated
Wrist flexed
What does the “Waiter’s Tip” position suggest pathologically?
What are the main causes of this condition?
Erb’s palsy, Traction of the brachial plexus (specifically C5/6 aka the superior trunk)
Main cause is shoulder dystocia (complication of birth) as well as trauma causing traction/damage to superior trunk of B plexus
Patient presents with a totally clawed hand, what injury to the brachial plexus could cause this?
Klumpke’s Palsy, i.e. injury to the Inferior trunk (C8/T1). It affects the small hand muscles
Other than Erb’s (sup trunk) & Klumpke’s (Inf Trunk) what other common nerve palsies affect the brachial plexus?
Total Brachial Plexus Palsy.
Affecting C5-T1
Patient presents with a wasted deltoid and loss of sensation in their regimental badge area. They also mentioned having had a recent fracture of their arm?
What muscles does this nerve supply?
Axillary nerve (C5/6) palsy, commonly associated with surgical neck fractures of the humerus and shoulder dislocation.
It supplies the deltoid, teres minor and regimental badge area
What does the radial nerve arise from and supply?
C5-T1, arising from the post cord
Supplies:
- Triceps
- Brachioradialis
- ECRL & ECRB
- Finger extensors via PIN
- Posterior hand sensation via SRN
How would compression or entrapment of the radial nerve present?
Depends on the level its injured at:
- Compress SRN* at wrist –> lose sensation back of hands (e.g. handcuffs)
- Compress PIN** in forearm –> Lose finger extension
- Compress Radial in arm –> lose above + wrist extension
- Compress Radial in axilla –> Above + Elbow extension
- SRN = superficial radial nerve
- *PIN = posterior interosseus nerve
From where does the median nerve arise and what does it supply?
C5-T1, arises from medial & Lateral cords
Supplies:
- All forearm flexors except FCU & Medial half of FDP
- LOAF muscles in hand
- Sensation to radial 3.5 digits
What condition comes with median nerve palsy?
Carpal Tunnel Syndrome
What causes carpal tunnel syndrome?
Developmental
Trauma (Distal radial fracture)
Ganglia, fibroma or lipoma swelling
Inflammatory - Gout, rheumatoid, TB or Amyloid
Metabolic - Pregnancy, mucopolysaccharides & Hypothyroidism
How does carpal tunnel syndrome present?
Numbness/pain in lateral 3.5 fingers Nocturnal pain & paraesthesia Abductor Pollicis Brevis weakness \+ve Tinnels/Phalen's Signs Thenar wasting & ~scars + deformity
Where does the ulnar nerve arise and what does it supply?
C8/T1, arising from medial cord
Supplies FCU & medial 1/2 of FDP
+ Intrinsic hand muscles except LOAF
Sensation to Ulnar 1.5 digits
What are the LOAF Muscles?
The only intrinsic hand muscles not supplied by the ulna, they’re innervated by the median nerve:
- Lateral 2 Lumbricals
- Oppenens Pollicis
- Abductor Pollicis Brevis
- Flexor Pollicis Brevis
