Brachial plexus Flashcards
Which muscles are innervated by the axillary nerve?
Deltoid Teres minor (external rotator)
Where does the lat dorsi insert?
“A lady between two majors”
Bicipital groove, between pec major (anterior lip) and teres major (posterior lip)
What is the content of the suprascapular notch?
Roof: transverse scapular ligament
“Army over the bridge, Navy under the bridge”
Suprascapular artery over ligament
Suprascapular nerve under ligament
What is the difference between avulsion and rupture?
Avulsion: nerve torn from its attachment (spinal cords or muscle)
Rupture: traction force on an incompletely divided nerve causing a complete division with proximal/distal ends
5 diagnostic differences between preganglionic and postganglionic lesions
Pre-ganglionic:
- Winged scapula, no levator scapula, serratus anterior, rhomboid, elevation of diaphragm (all proximal motor nerves)
- head looking away from side
- Deafferentation/root pain
- No Tinel’s
- SNAPs present
- Histamine test positive: vasodilation, wheal & flair
Post-ganglionic:
- proximal muscles OK
- Diaphragm normal
- Present Tinel’s
- Sweating in the palms
- Histamine test negative
What does a positive histamine triple response test mean?
If vasodilation, wheal, flare after injection + skin denervation
= Axonal reflex involving DRG
= PRE-ganglionic lesion
What is the priority of repair for adult total BP palsy?
Elbow flexion
Shoulder stability, abduction, external rotation
Sensation below elbow C6-7 (lateral cord)
Wrist and finger flexion
Wrist and finger extension
Intrinsic hand function
How to check intra-operatively for nerve continuity?
1) Between spinal cord and nerve:
- Somatosensory evoked potentials (SSEPs)
- Motor evoked potentials (MEPs)
2) Conduction across nerve:
- nerve action potential (NAP)
3) Conduction across nerve lesion to muscle:
- compound muscle action potential (CMAP)
4) Histochemical (limited to 5 days after injury):
- thiocholine (motor)
- carbonic anhydrase (sensory)
- choline acetyl transferase activity
