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Spiral Cords

- Discussion
   - arises from thickening, contracture, and coalescence of the spiral band, Grayson's liagment, and the lateral digital sheet; 
   - it extends disatlly past the natatory ligament, first lying along lateral margin of the digit, but then courses toward the midline to insert into the central cord at the level of the distal PIP joint; 
   - w/ time the spiral cord tends to straighten; 

- Relationship to Neurovascular Bundle
   - the spiral cord passes underneath the N/V bundle (just before it inserts into the natatory ligament) 
   - contracture of the spiral cord will straighten the cord and will also draw the N/V bundle superficially to the midline (causing it to spiral); 
   - hence, it is actually the neurovascular bundle which spirals; 
   - spiral cord lies at first dorsal & then palmar to neurovascular bundle as it spirals to blend with Greyson's ligament and attaches to tendon sheath; 
   - since neurovascular bundle may lie palmar to diseased spiral cord, the bundle may be injured by surgical dissection; 
   - hence the N/V vessel is vulnerable to surgical dissection since it is drawn toward the midline, and lies superfical to the cord at its maximal point of displacement; 
   - PIP joint contracture will move the vulnerable point proximally; 

- Exam
   - an elevated pouch of circular soft pulpy prominence in digit web space suggests spiral cord involvement of N/V bundle; 
   - palpation cord arising from abductor digiti quinti may indicate that ulnar N/V bundle to little finger may be displaced to midline