This thesis is an investigation of the role of skin and muscle receptors in proprioception at the ankle joint in humans. Somatosensory afferents provide the central nervous system with cues that code for movement and position of the segments, senses collectively known as proprioception. Intramuscular receptors, in particular muscle spindles, code for length and movement velocity of muscles surrounding a joint and therefore play an integral role in proprioception. The role of cutaneous receptors is less clear. When activated via skin stretch they create illusory movements of the limbs, and they are capable of responding to movements of the joints. To what extent these cues are utilized over and above input from muscle spindles remains unknown. In addition, there is evidence that cutaneous receptors may influence the sensitivity of muscle spindles by modulating their level of fusimotor activation. The aim of this thesis was to further examine the role of skin in proprioception and to determine whether or not skin of the foot and ankle is capable of modulating fusimotor drive to muscle spindles of the lower limb. The current thesis is comprised of three studies. The first experiment utilized a matching task at the ankle joint and determined that skin from the dorsum of the foot and ankle is necessary for accurate proprioception. The remaining two experiments used the technique of microneurography to record from single nerve afferents in awake, human participants. Initially, cutaneous afferents were isolated and recorded to determine the efficacy of using cooling over their receptive field as a method to decrease their sensitivity and output. Once cooling was established as an effective tool, the final experiment isolated and recorded from muscle spindles in response to passive, ramp and hold movements at the ankle. It was determined that a reduction in skin input (via cooling) altered the firing response of a portion of spindles. It is likely that this change in firing was due to modulation of fusimotor drive to the spindles. Collectively, the current work contributes the novel findings that skin on the dorsum of the foot is necessary for accurate proprioception at the ankle and that this is largely due to the role of skin as an independent proprioceptive channel. In addition, we have shown for the first time that a reduction in skin input from the foot dorsum is capable of modulating spindle discharge during a passive ramp and hold movement at the ankle, demonstrating a minor role for this interaction in proprioception. A secondary finding of the thesis was that cooling with ice is an effective tool for reducing input from all four classes of cutaneous mechanoreceptors.

Thesis (MAppSc in Physiotherapy)--University of South Australia, 1995

Thesis (M.S.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains vi, 91 p. : ill. (some col.). Includes abstract. Includes bibliographical references.

Thesis (M.A.)--University of North Carolina at Chapel Hill, 2004. / Includes bibliographical references (leaves 105-109). Also available online (PDF file) by a subscription to the set or by purchasing the individual file.

Thesis (M.S.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains viii, 107 p. : ill. (some col.). Includes abstract. Includes bibliographical references.

Thesis (M.A.)--University of North Carolina at Chapel Hill, 2004. / Includes bibliographical references (leaves 105-109).

Thesis (M.S.)--West Virginia University, 2005. / Includes bibliographical references. Also available online (PDF file) by a subscription to the set or by purchasing the individual file.

Thesis (M.S.)--West Virginia University, 2005. / Includes bibliographical references.

Shoulder complaints constitute a significant portion of primary care visits each year in the US, costing $7 billion in annual medical treatment. Shoulder complaints arise from some type of trauma caused by muscle imbalances, proprioception, overuse, anatomical or a combination of these factors. More than two thirds of complaints involve the rotator cuff. Literature regarding shoulder mechanics and proprioception is mixed and with contradictory results. This may be the reason for the high incidence and low success rate in treating shoulder complaints. Here the contributions of the supraspinatus muscle to humeral elevation, and shoulder proprioception are investigated. The results of this dissertation are applicable to developing shoulder injury treatment and preventative strategies, computational shoulder models, and understanding proprioception at the shoulder. This dissertation includes previously published and unpublished co-authored material.

The aims of this study were to; determine if it is possible for amputees to identify walking surfaces by receiving feedback through their prostheses. determine if there are any measurable changes in amputee gait characteristics when walking on different surfaces.   Methods Subjects walked on a specially built walkway with exchangeable surface materials (level, soft and tilted) with visual and audio feedback occluded. Subjects were required to identify the surface material. Kinematic data were collected simultaneously.   Results Agreement between the true surface and that identified by the subject on the amputated side was fair to good (k=0.58). A two way repeated measures ANOVA showed a significant difference in lateral knee displacement between heel contact to foot flat, with main effect for surface (p=0.010).   Conclusion Amputees have a fair to good ability to identify walking surfaces without additional information from eye sight, hearing or the sound limb.   The kinematic measures showed a significant increase in lateral knee displacement between heel contact to foot flat on the tilted surface compared to both level and soft surfaces. This was the case for both the amputated and the sound side.   The duration of heel contact to foot flat was unaffected by walking surface and first or second step. / Titel: Transtibialt amputerades varseblivning av gångunderlag – En pilotstudie   Syftet med studien var att; undersöka om det är möjligt för en amputerad att identifiera gångunderlag genom informationen de får via protesen. undersöka om det existerar några mätbara förändringar i den amputerades gångmönster på olika underlag.   Metod Försökspersonerna gick på en specialbyggd gångbana med utbytbart gångunderlag (plant, mjukt och vinklat), med visuella intryck och ljud från gångbanan isolerade. Försökspersonerna ombads identifiera gångunderlaget. Kinematiska data samlades in simultant.   Resultat Överensstämmelse mellan det verkliga underlaget och det som rapporterades av försökspersonen var godkänt till bra (k=0,58). En two way repeated measures ANOVA visade en signifikant skillnad gällande lateral knärörelse mellan hälisättning och framfotsisättning, med huvudeffekt för gångunderlag (p=0,010).   Slutsats Amputerade har en godkänt till bra förmåga att identifiera gångunderlag utan extra information från syn, hörsel eller från det friska benet.   Kinematiska data visade en signifikant ökning av lateral knärörelse mellan hälisättning och framfotsisättning på det vinklade underlaget jämfört med både det plana och det mjuka underlaget. Detta gällde för både amputerad och frisk sida.   Tiden för hälisättning till framfotsisättning var ej påverkad av gångunderlag, och inte heller av om det var första eller andra steget.