Knee

The generative force; vitality; strength.  To place on the knee symbolized recognition of paternity; adoption; maternal care.  Kneeling depicts homage to a superior, supplication, submission and inferiority.  From:  An Illustrated Encyclopaedia of Traditional Symbols (J.C. Cooper)

  Songs referenced: 

Alamo

Concertina

Merman

Northern Lad

Sweet Dreams