We present the development of a vision-feedback method to characterize how selective paralysis distorts the three-dimensional (3D) volume representing digit-tip force production capability and its application to healthy individuals producing thumb-tip force with and without simulated low ulnar nerve palsy (LUNP). Subjects produced maximal static voluntary force spanning the transverse, sagittal...

BACKGROUND For surgical reconstruction of lateral pinch following tetraplegia, the function of the paralyzed flexor pollicis longus is commonly restored. The purpose of this study was to investigate if one of the intrinsic muscles could generate a more suitably directed thumb-tip force during lateral pinch than that of flexor pollicis longus. METHODS Endpoint force resulting from 10 N applied...

To produce a torque about a joint in the human body there must be sufficient drive to excite motor neurones in the spinal cord to discharge action potentials. The number of motor neurones that are recruited, and the rate at which those motor neurones discharge action potentials, is directly linked to the summation of twitch forces in the muscle. However, the potential to generate a torque also ...

To investigate the organization of multi-fingered grasping, we asked subjects to grasp an object using three digits: the thumb, the index finger, and the middle or ring finger. The object had three coarse flat contact surfaces, whose locations and orientations were varied systematically. Subjects were asked to grasp and lift the object and then to hold it statically. We analyzed the grasp force...

38 Objective: The purpose of this study was to investigate altered finger-thumb coupling in 39 individuals with chronic hemiparesis post-stroke. 40 Methods: First, an external device stretched finger flexor muscles by passively rotating the 41 metacarpophalangeal (MCP) joints. Subjects then performed isometric finger or thumb force 42 generation. Forces/torques and electromyographic (EMG) signa...

The purpose of this study was to investigate altered finger-thumb coupling in individuals with chronic hemiparesis poststroke. First, an external device stretched finger flexor muscles by passively rotating the metacarpophalangeal (MCP) joints. Subjects then performed isometric finger or thumb force generation. Forces/torques and electromyographic signals were recorded for both the thumb and fi...

The control of whole hand grasping relies on complex coordination of multiple forces. While many studies have characterized the coordination of finger forces and torques, the control of hand muscle activity underlying multi-digit grasping has not been studied to the same extent. Motor-unit synchrony across finger muscles or muscle compartments might be one of the factors underlying the limited ...

The control of whole hand grasping relies on complex coordination of multiple forces. While many studies have characterized the coordination of finger forces and torques, the control of hand muscle activity underlying multi-digit grasping has not been studied to the same extent. Motor unit synchrony across finger muscles or muscle compartments might be one of the factors underlying the limited ...

Background: The trapeziometacarpal joint (TMCJ) is inherently unstable, relying on ligament restraint to preventsubluxation. Subluxation of the thumb in a dorsoradial direction is often observed in clinical practice, either after acuteligament injury or more commonly with osteoarthritis (OA). This subluxation follows loss of function of trapeziometacarpalligaments that stabilise this joint, res...