← All decks
Orthopaedics
Lesions of the Posterior Branch of the Axillary Nerve
Built from Pillemer — Physical Signs in Orthopaedics and Neurology
What’s inside
6 sections · 36 slides
The Big Picture
Why one small nerve branch matters
- What this topic is about
- Why a nerve splitting into branches matters
- Axillary nerve lesions: the familiar version
- The new idea: a lesion of just the posterior branch
Anatomy
Tracing the nerve from plexus to shoulder
- Where the axillary nerve begins in the brachial plexus
- The brachial plexus and the posterior cord
- The course: heading backwards to the shoulder
- The quadrilateral space and the axillary nerve
- Boundaries of the quadrilateral space
- The split into two branches
- Two branches, two jobs
- Skin territory of the axillary nerve
- The sensory patch you must test
- Whole nerve versus posterior branch: a key contrast
Mechanism of Injury
How the branch gets hurt
- How the posterior branch is injured
Clinical Presentation
What the patient shows you
- The one finding present in every case
- Wasting of the posterior deltoid versus the normal side
- Posterior deltoid wasting: helpful but not constant
- Localised tenderness: the third clue
- Comparing affected and unaffected shoulders
- What to notice when you compare the shoulders
- Why the diagnosis keeps being missed
Diagnosis
Three findings to nail it down
- The three diagnostic findings
- Reading the three findings together
Clinical Significance
Why getting this right protects patients
- Why the missed diagnosis leads to the wrong surgery
- Post-fall shoulder pain, ultrasound reports sub-deltoid bursitis. What single bedside test could change management?
- Summary: the whole story on one slide
- References
- Physical Signs in Orthopedic and Neurologic Disorders: A Practical Guide