The mechanoreceptor innervation of the posterior attachments of the lateral meniscus of the dog knee joint.

The posterior attachments of the dog knee joint lateral menisci have been studied to identify and characterize their mechanoreceptor innervation. Two basic types of mechanoreceptor were identified that appeared to be similar to the Type III and Type II endings described by Freeman & Wyke (1967) in cat knee periarticular tissues. Significantly, two distinct forms of Type II corpuscles were identified in this study, referred to as Types IIa and IIb, respectively. Endings were usually identified either at the point where the posterior meniscotibial ligament merged with the main body of the meniscus and the meniscofemoral ligament, or within the inner aspect of the meniscofemoral ligament where it joined the meniscal 'body'. The presence of encapsulated mechanoreceptors within the attachments of dog knee lateral menisci means that the central nervous system is being appraised of the mechanical state of these structures. A mechanism is suggested by which the tension of meniscal attachments could be varied according to knee joint position. A possible relationship between the morphology of the receptors identified in this study and the physiological responses of similar cat knee joint receptors is discussed.