ABSTRACT
Background The afferent signals of proprioceptor in extraocular muscles play an important role in controlling eye position and conjugate movement. Palisade ending in the extraocular muscles is the main source of proprioceptive information, and its abnormalities in structure and function may be associated with the occurrence of nystagmus. Objective This study was to observe the changes of palisade ending in the extraocular muscles of patients with congenital nystagmus ( CN) and discuss the probable mechanism. Methods Modified Kestenbaum procedure was performed on 10 patients with CN, and the extraocular muscle samples were collected during the operation. Normal extraocular muscle samples were obtained from the enucleated eyeballs after ocular wound. The ultrathin sections of extraocular muscles were prepared and double-staining by uranyl acetate and lead citrate. The morphological changes of the palisade ending of extraocular muscles were examined under the transmission electron microscopy. Written informed consent was obtained from each subject before surgery. Results The ultrastructure of palisade ending in the extraocular muscle of CN subjects showed the different degrees of alterations. The mild changes included the collapse and disconnection of external capsules and the nonhomogeneous electron-dense substracts. The degeneration and dissociation of myelin in nerve endings, swelling and vacuolation of mitochondria were also exhibited. Myeloid body was found in axon. In the severe patients,the necrosis of Schwann' s cells,dissolve of axon and disappear of capsules were seen. Conclusion The palisade ending of extraocular muscle in the patients with CN are obviously abnormal in comparison with normal one. These alterations are probably associated with the etiology and pathogenesis of CN.
ABSTRACT
Proprioception plays an important role in the maintenance of joint stability and regulation of joint motion. Previous studies have suggested that dysfunction of proprioception is related to causal factors of various diseases and injuries of the musculoskeletal system. In recent years, training of proprioceptive function has been introduced for the rehabilitation of motor function and prevention of the joint injuries.In this review paper, definition of proprioception, and morphologic and physiologic characteristics of the proprioceptors in the joint and adjacent tissues such as ligaments, muscles and tendons are described. Previous clinical studies on the relationships between proprioceptive dysfunction and joint diseases and injuries are also reviewed.
ABSTRACT
To verify the postoperative ultrastructural changes of the myotendinous nerve endings of feline extraocular muscles, which are known as proprioceptors. Sixteen recti of four cats were used and divided into three groups. In group A, eight lateral recti were recessed. In group B, four medial recti were resected by 10 mm from insertion to include the myotendinous junction. In group C, four medial recti were resected by 4 mm of muscle bellies only, without disturbing the myotendinous junction. Four weeks after surgery, specimens were examined with electron microscopy. In group A, overall neural structures were well maintained with slight axonal degeneration. In group B, only muscle fibers were observed without any regeneration of neural sprouts. In group C, axonal disintegration and shrinkage were evident. These results indicate that myotendinous nerve endings can be damaged in strabismus surgery, and that resection was more invasive than recession in disrupting myotendinous nerve endings.