The Mechanism of Walking & Nerve Lesions PDF

THE MECHANISM OF WALKING & NERVE LESIONS MDM NOOR AZIMAH BT NORBIDIN  Topic Learning Outcomes (TLOs) 1. Describe and explain what is gait. 2. Describe the phases of gait cycle. 3. Explain nerve lesions. 4. Describe the types of nerve injury.  Gait Study o...

THE MECHANISM OF WALKING & NERVE LESIONS MDM NOOR AZIMAH BT NORBIDIN  Topic Learning Outcomes (TLOs) 1. Describe and explain what is gait. 2. Describe the phases of gait cycle. 3. Explain nerve lesions. 4. Describe the types of nerve injury.  Gait Study of human locomoUon Walking and running Walking is a series of gait cycles – A single gait cycle is known as a stride  DefiniUon: Physiology A mechanism which depends upon closely integrated acUon of the subjects, bones, muscles and nervous system (including peripheral and central nervous system) The degree of integraUon determines the different gait pa\erns. Any defect of any part of them or all of them will lead to pathological gait.  DefiniUon: Mechanical A form of bipedal locomoUon as there is an alternaUng acUon between lower extremiUes. One leg is in touch with the ground for restraining, supporUng and propulsion. The other leg is in swing phase for creaUng a new step forward. So gait is the result of a series of rhythmic alternaUng movement of arms, legs, and trunk which create forward movement of the body. ar W Normal Walking Requirements & There are (4) major criteria essenUal to walking. Equilibrium – the ability to assume an upright posture and maintain balance. LocomoUon – the ability to iniUate and maintain rhythmic stepping  Normal Walking Requirements Musculoskeletal Integrity – normal bone, joint, and muscle funcUon Neurological Control – must receive and send messages telling the body how and when to move (visual, vesUbular, auditory, sensorimotor input)  Gait Cycle or Stride A single gait cycle or stride is defined: Period when 1 foot contacts the ground to when that same foot contacts the ground again Each stride has 2 phases: – Stance Phase Foot in contact with the ground – Swing Phase Foot not in contact with the ground  A Single Gait Cycle or Stride auto S  Gait cycle n atte  The Main Tasks of the Gait Cycle (1) Weight acceptance most demanding task in the gait cycle involves the transfer of body weight onto a limb that has just finished swinging forward and has an unstable alignment. Shock absorpUon and the maintenance of a forward body progression  The Main Tasks of the Gait Cycle (2) single limb support One limb must support the enUre body weight Same limb must provide truncal stability while bodily progression is conUnued. (3) limb advancement Requires foot clearance from the floor The limb swings through three posiUons as it travels to its desUnaUon in front of the body.  Phases of Gait cycle: Stance Phase Defined as the interval in which the foot is on the ground (60% of the gait cycle). Divided into: > i. Heel strike to foot flat ii. Foot flat through mid-stance · iii. Mid-stance through Heel off iv. Heel off to Toe off.  r immit Stance Phase of Gait - Soalan minta describe h OBA When the foot is contact Ciarang with the ground only Propulsion phase Stance phase has 5 parts: – IniUal Contact (Heel Strike) (1) – Loading Response (Foot Flat) (2) – Midstance (2) – Terminal Stance (3) – Toe Off (Pre-Swing) (4)  CharacterisUcs of Stance Phase During a single stride, there are 2 periods of double limb support (both feet on ground): – Loading response (right) & Toe Off (led) – Loading response (led) & Toe Off (right)  Phases of Gait Cycle: Swing Phase Defined as the interval in which the foot is not in contact with the ground (40% of the gait cycle). Denotes the Ume when the foot is in the air, consUtuUng the remaining 38 percent of the gait cycle. The swing phase could be defined as the phase when all porUons of the foot are in forward moUon.  Swing Phase When foot is not contacUng the ground, it is swinging! Limb advancement phase 3 parts of swing phase: – IniUal swing – Midswing – Terminal swing  Swing Phase Swing is divided into two phases 1) AcceleraUon to mid-swing 2) Mid-swing to deceleraUon The swing period primarily is divided into three parts: iniUal swing, mid-swing and terminal swing. *multknow Pre-swing, however, prepares the limb for swing advancement and in that sense could be considered a component of swing phase.  et sont Nerve Lesions I Neuron is the basic funcUon unit of the nervous system. In mature human, if it’s destroyed, it is not replaced. It may be injured due to various reasons i.e. cuhng, crushing, pull & pressure. These injuries may damage a nerve variously & the injury is classified according to the extent of the damage. i aerr  Types of nerves Cranial – motor, sensory, mixed Spinal nerves – sympatheUc, parasympatheUc Myelinated, non-myelinated  Types of nerves Nerve fibers: A-alpha – largest fiber, fastest conducUon, fine touch, posiUon A-beta – prociocepUon (balancinal A-delta – sharp pain, fast C fibers – slow pain  ClassificaUon of nerve injury auto Based on: 1. The damage sustained by the nerve components 2. Nerve funcUonality 3. The ability for spontaneous recovery  now Nerve injury must Seddon (1944) described 3 clinical types of nerve injury: Neurapraxia (Class I) the term applied to a transient block paralysis is incomplete, recovery is rapid & complete, and there is no nerve degeneraUon pressure is the most common cause th guna mouse law a suht not writ  Axonotmesis (Class II) The term applied to a nerve lesion in which the axons are damaged but the surrounding connecUve Ussue sheaths remain intact Wallerian degeneraUon occurs peripherally FuncUonal recovery is more rapid & more complete than ader complete secUon of the nerve trunk Crush injuries, tracUon, & compression are the most common causes  Neurometsis (Class III) The term applied to complete secUon of the nerve trunk Occur on severe contusion, stretch, laceraUon  Nerve injury Sunderland (1951) expanded Seddon’s classificaUon to 5 degrees: First-degree (Class I) Seddon’s neurapraxia & first-degree are the same Second-degree (Class II) Seddon’s axonotmesis & second-degree are the same  Nerve injury Third-degree (class II) Nerve fiber interrupUon There is a lesion of the endoneurium, but the epineurium & perineurium remain intact Recovery from a third-degree injury is possible, but surgical intervenUon may be required  Nerve injury Fourth-degree (class II) Only the epineurium remain intact Surgical repair is required Fidh-degree (class III) -memang terh Lesion of complete transecUon of the nerve Recovery is not possible without an appropriate surgical treatment  Injury of the nerve cell body Severe damage of the nerve cell body may result in degeneraUon of the enUre neuron In the CNS, the Ussue macrophages (microglial cells) remove the debris, & the neighboring astrocytes replace the neuron with scar Ussue In the PNS, the Ussue macrophages remove the debris, & the local fibroblasts replace the neuron with scar Ussue  Injury of the nerve cell process If the axon of the nerve cell is divided, degeneraUve changes will take place in 1. Distal segment of the axon 2. A porUon of the axon proximal to the injury 3. The cell body from which the axon arises  Changes in the distal segment of the bila ada herve fakan axon jadi scar Issue akan means recover - Wallerian degeneraUon is the changes that occur distally to the site of damage on an axon Axon becomes swollen & irregular; the axon is broken into fragments, & the debris is digested by surrounding Schwann cells & Ussue macrophages EnUre axon is destroyed within a week  Changes in the distal segment of the axon Myelin sheath is converted into lipid droplets The droplets are extruded from the Schwann cell & subsequently are phagocytosed by Ussue macrophages Schwann cells now begin to proliferate rapidly & axonal sprouts grow from the proximal stump, enter the distal stump, & grow toward the nerve's end-organs If regeneraUon does not occur, the axon & the Schwann cells are replaced by fibrous Ussue produced by local fibroblasts  Changes in the Proximal Segment of the Axon The changes in the proximal segment of the axon are similar to those that take place in the distal segment but extend only proximally above the lesion as far as the first node of Ranvier  Changes in the nerve cell body The changes that occur in the cell body following injury to its axon are referred to as retrograde degeneraUon The Nissl material becomes fine, granular, & dispersed throughout the cytoplasm (chromatolysis) The nucleus moves toward the periphery of the cell, & the cell body swells & becomes rounded SynapUc terminals are replaced by Schwann cells in the PNS & microglial cells or astrocytes in the CNS Recovery of Neurons Following Injury The recovery of the nerve cell body & regeneraUon of its processes may take several months  Recovery of the Nerve Cell Body RNA & protein synthesis is accelerated a reconsUtuUon of the original Nissl structure a decrease in the swelling of the cell body a return of nucleus to its characterisUc central posiUon  RegeneraUon of Axons in Peripheral Nerves Depend on endoneurial tubes & possessed by Schwann cells The following mechanisms are involved: 1. The axons are a\racted by chemotropic factors secreted by the Schwann cells in the distal stump, 2. Growth-sUmulaUng factors exist within the distal stump, & 3. Inhibitory factors are present in the perineurium to inhibit the axons from leaving the nerve  RegeneraUon of Axons in the CNS Central axons may not be as good at regeneraUon as peripheral axons The regeneraUon process is aborted by – Failure of oligodendrocytes to serve in the same manner as Schwann cells, – Laying down of scar Ussue by the acUve astrocytes – Absence of nerve growth factors in the CNS – Neuroglial cells may produce nerve growth-inhibiUng factors  Some Terminologies Paralysis – loss of motor funcUon Paresis – incomplete loss of motor funcUon Anesthesia – loss of all sensaUon Hyperesthesia – excessive sensaUon Hypoesthesia – diminished sensaUon Hyperalgia – excessive sensiUvity to painful sUmuli Hypoalgesia – lowered pain sensiUvity THANK YOU!