Morphological study of mechanoreceptors in ligaments of the trapeziometacarpal joint

Abstract

The complex stability of the trapeziometacarpal (TMC) joint depends on the role of ligaments and muscles around joints. The mechanoreceptors within ligaments and adequate regulation of peripheral neuromuscle reflexes promote joint dynamic stability. We know that the dorsal radial ligaments (DRL) and anterior oblique ligaments (AOL) play most respective roles of in controlling the stability of the TMC joint. This experiment has the following purposes (1) we want to describe the shape and distribution of mechanoreceptors in DRL and AOL of TMC joint using modified gold chloride staining techniques. (2) To explore whether there is a relationship between gender and the number of mechanoreceptors. Normal specimens of the thumb ligament were obtained from the upper limbs of 12 fresh frozen cadavers. The length, width and thickness of the DRL and AOL were measured. The DRLs and the AOLs were divided into the proximal, middle and distal sections. Each segments of ligament were made into 5 μm thick slices. The slices were stained by modified gold chlorine staining techniques after the slices were dehydrated with 70% alcohol. All the four typical types of nerve endings (the Ruffini corpuscles, Pacinian corpuscles, Golgi corpuscles, and free nerve endings) were found in these ligaments. Pacinian corpuscles were the predominant in all four complexes. Most mechanoreceptors were found in synovial membrane near both ends of the ligaments attached to the bone. The DRL was significantly thicker and tougher than the AOL. The DRL had significantly more mechanoreceptors than AOL. There were significant differences in terms of the number of whole mechanoreceptors in the DRL and the AOL due to the differences of gender. The morphology and distribution of mechanoreceptors are different from those reported in previous literature, suggesting that TMC joint have more complex proprioceptive functions. The proprioception of TMC joint in male maybe more powerful than female.