Type A:
Adjacent to joint, tendon is within the joint capsule
e.g. patella, 1st MCPJ sesemoids (2 in number, within the tendons of adductor pollicis and FPB)
Type B:
At the level of angling of the tendons, seperated from bone by synovial lined bursa
e.g. common in feet, peroneaus longus sesemoid
References:
Resnick et al, Bone and joint imaging, 3rd edition, Elsevier Saunders publications
