A quantitative study of muscle spindles and tendon organs in some intrinsic muscles of the hand in the bonnet monkey (Macaca radiata)

The number and density of muscle spindles and tendon organs have been determined in the following intrinsic muscles of the hand of bonnet monkeys: I lumbrical, II lumbrical, abductor digiti minimi, adductor pollicis, and I dorsal interosseous. All these muscles were found to be very rich in muscle spindles (17.6 to 42.31 per gram wet weight) but relatively poor in tendon organs (0.606 to 10.06 per gram wet weight). The lumbricals have very few tendon organs. The possible functional significance of these findings has been discussed.