Anatomy of the juncturae tendinum of the hand

Three distinct morphologic types of juncturae tendinum of the extensor tendons were identified in the dissection of 40 cadaver hands. Type 1 juncturae consists of filamentous regions within the intertendinous fascia that attached to the extensor tendons on either side of the intermetacarpal space in a transverse or oblique direction. The second type, consists of much thicker and well-defined connecting bands. Type 3 juncturae consist of tendon slips from the extensor tendons and were subclassified into "y" or "r" subtypes depending on shape. Type 1 juncturae were present in 88% of the second intermetacarpal spaces and in 28% of the third intermetacarpal spaces. Type 2 juncturae were present in 40% of the third intermetacarpal spaces and in 23% of the fourth intermetacarpal spaces. Type 3 juncturae were present in 33% of the third intermetacarpal spaces and in 80% of the fourth intermetacarpal spaces. Juncturae were absent in all of the first intermetacarpal spaces and in 12% of the second intermetacarpal spaces; they were present in all other spaces. The extensor indicis proprius did not receive a junctural connection, whereas extensor digiti quinti tendons did receive junctural connections. Intertendinous fascia was present between all extensor digitorum communis tendons regardless of presence of juncturae.