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Orthopaedics
The Ulnar Nerve
Built from Pillemer — Physical Signs in Orthopaedics and Neurology
What’s inside
8 sections · 64 slides
Overview
- What this topic covers
Anatomy
Where the nerve begins and the path it follows to the hand
- Where the ulnar nerve comes from
- Ulnar nerve as a terminal branch of the brachial plexus
- The journey down the arm
- The ulnar nerve in the arm
- At the elbow: the exposed corner
- The ulnar nerve at the elbow
- At the wrist: entering the hand
- Guyon's canal at the wrist
Function
The muscles it powers and the skin it supplies
- Motor supply: what the nerve moves
- The intrinsic muscles, one job at a time
- A memory hook for the interossei
- Ulnar intrinsic muscle actions and sensory territory
- Sensory supply: the skin it feels for
Testing motor function
Examining each ulnar muscle group at the bedside
- Adduction of the fingers
- Testing finger adduction
- Abduction of the fingers
- Testing finger abduction
- Palpating the first dorsal interosseous
- The sign of long-standing damage: wasting
- Wasting and clawing in a chronic ulnar lesion
- Adduction of the thumb and Froment's sign
- Positive Froment's sign
- A subtlety worth knowing
- Thumb IP flexion during adduction
Testing sensory function
Mapping feeling and the tricks for a patient who cannot cooperate
- Three nerves share the hand
- Autonomous zones: the reliable spots
- Autonomous zones of the median and ulnar nerves (palm)
- Autonomous zone of the radial nerve (dorsum)
- How to test sensation well
- A bent K-wire used for sensory testing
- Testing a patient who cannot cooperate
- Two clever tricks that need no words
- The violin test
- The violin test with tissue paper
- The prune test
Lesions of the ulnar nerve
The two sites where the nerve is commonly trapped
- Cubital tunnel syndrome: the elbow
- Cubital tunnel syndrome: the physical signs
- Ulnar tunnel syndrome (Guyon's canal): the wrist
- Wrist lesion versus elbow lesion
- Guyon's canal: anatomical boundaries
- Anatomical boundaries of Guyon's canal
The ulnar claw hand
Why the deformity looks the way it does
- The ulnar claw hand deformity
- Two ideas unlock the whole deformity
- Balanced versus unbalanced paralysis
- Why the distinction changes treatment
- What the intrinsic muscles do
- Normal intrinsic action: flexion at MP, extension at IP
- Putting it together: the claw explained
- Why does the ulnar claw hand form?
The ulnar paradox
Why a worse lesion looks milder
- Low versus high ulnar lesion
- Why it is called a paradox
- Numbers worth remembering
- Key takeaways
- References
- Physical Signs in Orthopedic and Neurologic Disorders: A Practical Guide