In the process of walking
/ gait there is a complex process that is influenced by a number of
mechanisms of the body, and is the result of the collaboration of the
various types of reflex. Walk normally usually do not attract attention .
Walking impairment can be found in a variety of circumstances .
Mechanical factors such as diseases of the muscles, bones, tendons, and
joints play an important role in the occurrence of walking impairment .
Diseases
of the nervous system very often lead to impaired walking, and
sometimes just by considering it can be determined how walking the
disease to the nervous system. Walking impairment can be the result of a
motor system disorder levels ( motor cortex and descending pathways,
complex extrapyramidal, cerebellar anterior horn cells, peripheral
motor nerves or muscles ). Other disorders that can also cause
disturbance / change gait is impaired psychomotor ( hysteria and
malingering ), vestibular complex disorders, disorders of sensory nerve,
posterior columns, and averen cerebellar pathway .
Anatomy and Physiology of Walking
Walking processes is a complex process that requires the integrity of the various structures and neural mechanisms . Structure and neural mechanisms of this organized arrangement for running the process .
1. Motor Cortex
Primary motor cortex ( Brodmann area 4 ) lies on precentral gyrus frontal lobe , extending from the lateral fissure to the limit of the dorsal surface of the hemisphere and most media rostal frontal lobe of paracentral lobule. Primary motor cortex associated with the appearance of movement. Next rostal primary motor area, there premotor cortex ( Brodmann area 6 ). On the lateral surface hemisper associated with ( initiation ) movement. Supplementary motor area located on the medial aspect of area 6 in the sagittal section, rostal of paracentral lobule. This area is active during movement preparation after inisasi movement. This area functions primarily associated with complex movements in the limbs including joint limb movements on both sides of the body. Descending pathway from the cerebral cortex is affecting motor activity.
2. Corticospinal tract ( pyramidal )
This pathway initially considered as the start and control all voluntary muscle activity . It was determined that this pathway is mainly associated with the movement of trained muscles distal limb and the facilitation of α, β and t motorneuron. One third of the axons of this pathway from the primary motor cortex (area 4 and 6 ) other one-third of the promoter area and supplementary motor area , and the remaining third comes from the parietal lobe ( areas 3, 1 and 2 ). Corticospinal tract and then walked toward an advanced distal who then divided the lateral corticospinal tract ( 90 % ) and ventral corticospinal tract. Lateral corticospinal tract runs on funikulus lateral spinal cord and synapse on the lateral aspect of the conduct lamina IV to VIII. Many cells in the lamina are interneurons that synapse with α complain, and t motor neuron in lamina IX. Corticospinal tract effects, facilitation and inhibition of spinal interneurons and motor neuron. Activation of corticospinal tract generally cause excitatory postsynaptic potential in the interneuron and motorneuron of the flexor muscles and inhibitory postsynaptic potential in extensor muscles .
3. Corticorubral and Rubrospinal Tract
Derived from the cerebral cortex, the fibers of the nucleus toward the tegmentum ipsilateral mesencephalon rubra. Rubrospinal tract from the nucleus ruber that crosses the midline in the ventral tegmental cross and down through the lateral tegmentum pons and mesencephalon to the spinal cord. In the spinal cord, these pathways are in part arterior lateral corticospinal tract on the lateral funiculus. Fibers are forming synaps at each level of the spinal cord for the lateral aspect of lamina V, VI and VIII. This tract function is to facilitate flexor and extensor motor neuron inhibition α , β and
t, especially that innervate the distal forearm.
4. Vestibulospinal Tract
Vestibulospinal tract is walking towards the anterior funiculus and form synapses with cells in lamina VII and VIII . Vestribulospinal tract lateral run on the entire length of the spinal cord , while the medial vestibulospinal tract goes up as high as the top of the thoracic. Vestibulosspinal lateral tract stimulation, triggering excitatory postsynaptic potential in the motor neurons that innervate the extensor muscles of the neck, back, limbs. Stimulation of medial vestibulospinal tract does not affect motor neuron limb. Vestibulospinal pathways associated with postural movement of the head and body while maintaining postural tone. Pathway of motor systems originating from the cerebral cortex and brain stem and spinal cord achieve functionally consists of two common projection system, namely : the ventromedial and lateral. Brainstem ventromedial system consists of fibers derived from interstitial nucleus (Cajal), the superior colliculus, reticular formation (mesensephalon, pons, medulla oblongata ), and the vestibular nuclei . Tract is formed from these fibers end in the ventral and medial aspects of the anterior horn (including lamina VII and VIII). Ventromedial pathway is primarily concerned with the maintenance of upright posture , integrated movement of body and limbs and limb movement progressions. This pathway is generally facilitates the motor neurons that innervate activity in extensor muscles and inhibits the activity of the motor neurons that innervate the flexor muscles. Lateral system consists of the brain stem fibers originating from the contralateral nucleus magnocelluler rubber towards the spinal cord through rubrospinalis tract, and fibers from the ventrolateral tegmentum contralateral Pontis toward the spinal cord through the spinal cord lateral column. The lateral pathway fibers end in the dorsal and lateral aspects of the anterior horn, including lamina V, VI and VII . This pathway associated with smooth movements especially the hands and feet. This pathway is generally facilitate motorneuron activity for flexor muscles for activity and inhibits extensor muscles .
5. Cerebellum
The cerebellum is located in the posterior fossa , behind the pons and medulla oblongata . Separated from the cerebrum, at the top by the tentorium cerebellum. Cerebellum consists of 3 main anatomical components, flocculonodular lobe ( archi cerebellum ) anterior lobe ( paleo cerebellum ) and posterior lobe ( neo cerebellum ). Flocculonoduler lobe receives projections mainly from the vestibular nuclei. Especially in the anterior lobe vermis receives input from spinocerebellar pathways. Receives projections from the posterior lobe of the cerebral hemispheres. Cerebellar cortex consists of three layers, there are the molecular layer (a layer of Purkinje cells) and granular layer. In the cerebral hemispheres , there are 4 pairs of the fastigial nucleus, globosus, emboliformis and dentatus.
There are 3 pairs of major projection beam is superior cerebellar peduncle (brachium conjunctivum), pedunculus cerebelli media (brachium Pontis) and the inferior cerebellar peduncle (corpus restiforme) Cerebellar function is as a coordination center to maintain balance and muscle tone. Cerebellum is needed to maintain posture and balance for walking and running .
6. Basal ganglia
Basal ganglia are subcortical nuclei complex is the main component consisting of the caudate nucleus, putamen and globus palidus. Another component of the basal ganglia is complex amygdaloid nucleus, and claustrum. Another complex nuclei have strong relationships with the basal ganglia is subthalamicus nucleus and substantia nigra. Control of motor activity through a variety of circuits involving the basal ganglia, cerebral cortex and cerebellum then passed through the descending motor pathways which in turn affects the lower motorneuron activity. Movement is influenced by the basal ganglia are associated with posture, automatic movement (swing arms when walking), and skilled movement. Basal ganglia suspected of having a role in movement planning and movement synergies.
7. Spinal cord
The fibers of the pyramidal tract and various extrapyramidal pathways and afferent fibers that enter the spinal cord through the posterior root, ending at the cell body or dendrites of large and small α motor neuron and t motor neuron directly or via interneurons in the spinal cord. Nerve fibers with larger diameter (alpha-1) goes straight to the muscles ekstrafusal end as the motor end plate. Nerve fibers of t motor neurons innervate muscle spindles. The basic unit in the organization of the spinal cord are spinal reflexes. The spinal reflex get inhibition and excitation under the influence of these centers is higher. Spinal reflexes are activated and maintained by an external stimulus. There is a continuous interaction between the sensory input, excitation pathways through the spinal interneurons and supraspinal and motor output. The effect of the higher center activity is to modify and regulate the activity of the spinal reflexes. A spinal reflex arc consists of a sensory neuron, one or more interneurons and motor neurons with axons and branches leading to the muscle fibers of the motor unit. Spinal reflex inhibition associated with excitation, muscle contraction together (cocontraction) and reciprocal innervation of antagonistic muscles. The integrity of the spinal reflex is important in the movement which is basic of walk process.
8. Neural control of movement (locomotion)
To maintain posture, there is a tonic influence of the higher centers. This control also plays a role in the movement. Here tonic messages from the higher centers translates into a rhythmic locomotor output or periodic. Brown (1911) suggested that the movement is generated by neurons located in the spinal cord. Orlovsky et al (1960), reported there is an area in which, when stimulated lead mesensefalon running movement, called the mesencephalic locomotor region.
Basic rhythmic patterns of neural activity that lead to movement caused by intrinsic neurons in the central nervous system. So it can be said there is a movement central program. A central program is an expression of the neural circuits that produce a specific pattern of motor output that does not require afferent feedback, eg, contraction of muscles alternately pleksor-extensor during walking. Grillner and colleagues (1973) suggested that the central program located in the spinal cord (mainly in lamina IV and V). The program is also known as central pattern generators or neural oscillator. During locomotor movements, the neurons which is the origin of the tract rubrospinalis, vestibulospinal and reticulospinalis are in a rhythmically active state. A group of adrenergic neurons located in the locus ceruleus and the lower brain stem, sends axons to lumbo-sacral spinal cord. This group is suspected of neurons that mediates the action of mecencephalic locomotor region. Assenden information sent from the spinal cord to higher centers during movement. Spinocerebellar tract bring input to the cerebellum from muscle spindles, tendon organs and joint afferents. Dorsal Spinocerebellar tract neurons receiving afferent input from the muscle specific so easily influenced, while the ventral spinocerebellar tract receive input from the periphery is more diffuse and weaker so it is more difficult to influence. Both dorsal and ventral spinocerebellar tract neurons are in an active state (the wicked) during movement. The second tract spinocerebellar send different information to the cerebellum. Dorsal tract transmit information on muscle activity, whereas the ventral tract transmits information about active processes in the spinal cord (the generation of patterns of movement).
Efferent information has two important roles in the process of walking, the first one is to start the motor program from one phase to the next phase. During the walk there are two phases in the cycle are rare swing phase (swing phase) performed by the flexor muscles and the standing phase (phase snatce) conducted by the extensor muscles. Another role of afferent information during the process of running is opening and closing reflex pathway in various parts of the step cycle (step cycle). Stimulation at the top of the foot in the swing phase (flexion) adds leg flexion, as well as the stance phase (extension)
Source:
pict: http://www.mpiwg-berlin.mpg.de/en/research/projects/DeptII_Mayer_Walking
4. Vestibulospinal Tract
Vestibulospinal tract is walking towards the anterior funiculus and form synapses with cells in lamina VII and VIII . Vestribulospinal tract lateral run on the entire length of the spinal cord , while the medial vestibulospinal tract goes up as high as the top of the thoracic. Vestibulosspinal lateral tract stimulation, triggering excitatory postsynaptic potential in the motor neurons that innervate the extensor muscles of the neck, back, limbs. Stimulation of medial vestibulospinal tract does not affect motor neuron limb. Vestibulospinal pathways associated with postural movement of the head and body while maintaining postural tone. Pathway of motor systems originating from the cerebral cortex and brain stem and spinal cord achieve functionally consists of two common projection system, namely : the ventromedial and lateral. Brainstem ventromedial system consists of fibers derived from interstitial nucleus (Cajal), the superior colliculus, reticular formation (mesensephalon, pons, medulla oblongata ), and the vestibular nuclei . Tract is formed from these fibers end in the ventral and medial aspects of the anterior horn (including lamina VII and VIII). Ventromedial pathway is primarily concerned with the maintenance of upright posture , integrated movement of body and limbs and limb movement progressions. This pathway is generally facilitates the motor neurons that innervate activity in extensor muscles and inhibits the activity of the motor neurons that innervate the flexor muscles. Lateral system consists of the brain stem fibers originating from the contralateral nucleus magnocelluler rubber towards the spinal cord through rubrospinalis tract, and fibers from the ventrolateral tegmentum contralateral Pontis toward the spinal cord through the spinal cord lateral column. The lateral pathway fibers end in the dorsal and lateral aspects of the anterior horn, including lamina V, VI and VII . This pathway associated with smooth movements especially the hands and feet. This pathway is generally facilitate motorneuron activity for flexor muscles for activity and inhibits extensor muscles .
5. Cerebellum
The cerebellum is located in the posterior fossa , behind the pons and medulla oblongata . Separated from the cerebrum, at the top by the tentorium cerebellum. Cerebellum consists of 3 main anatomical components, flocculonodular lobe ( archi cerebellum ) anterior lobe ( paleo cerebellum ) and posterior lobe ( neo cerebellum ). Flocculonoduler lobe receives projections mainly from the vestibular nuclei. Especially in the anterior lobe vermis receives input from spinocerebellar pathways. Receives projections from the posterior lobe of the cerebral hemispheres. Cerebellar cortex consists of three layers, there are the molecular layer (a layer of Purkinje cells) and granular layer. In the cerebral hemispheres , there are 4 pairs of the fastigial nucleus, globosus, emboliformis and dentatus.
There are 3 pairs of major projection beam is superior cerebellar peduncle (brachium conjunctivum), pedunculus cerebelli media (brachium Pontis) and the inferior cerebellar peduncle (corpus restiforme) Cerebellar function is as a coordination center to maintain balance and muscle tone. Cerebellum is needed to maintain posture and balance for walking and running .
6. Basal ganglia
Basal ganglia are subcortical nuclei complex is the main component consisting of the caudate nucleus, putamen and globus palidus. Another component of the basal ganglia is complex amygdaloid nucleus, and claustrum. Another complex nuclei have strong relationships with the basal ganglia is subthalamicus nucleus and substantia nigra. Control of motor activity through a variety of circuits involving the basal ganglia, cerebral cortex and cerebellum then passed through the descending motor pathways which in turn affects the lower motorneuron activity. Movement is influenced by the basal ganglia are associated with posture, automatic movement (swing arms when walking), and skilled movement. Basal ganglia suspected of having a role in movement planning and movement synergies.
7. Spinal cord
The fibers of the pyramidal tract and various extrapyramidal pathways and afferent fibers that enter the spinal cord through the posterior root, ending at the cell body or dendrites of large and small α motor neuron and t motor neuron directly or via interneurons in the spinal cord. Nerve fibers with larger diameter (alpha-1) goes straight to the muscles ekstrafusal end as the motor end plate. Nerve fibers of t motor neurons innervate muscle spindles. The basic unit in the organization of the spinal cord are spinal reflexes. The spinal reflex get inhibition and excitation under the influence of these centers is higher. Spinal reflexes are activated and maintained by an external stimulus. There is a continuous interaction between the sensory input, excitation pathways through the spinal interneurons and supraspinal and motor output. The effect of the higher center activity is to modify and regulate the activity of the spinal reflexes. A spinal reflex arc consists of a sensory neuron, one or more interneurons and motor neurons with axons and branches leading to the muscle fibers of the motor unit. Spinal reflex inhibition associated with excitation, muscle contraction together (cocontraction) and reciprocal innervation of antagonistic muscles. The integrity of the spinal reflex is important in the movement which is basic of walk process.
8. Neural control of movement (locomotion)
To maintain posture, there is a tonic influence of the higher centers. This control also plays a role in the movement. Here tonic messages from the higher centers translates into a rhythmic locomotor output or periodic. Brown (1911) suggested that the movement is generated by neurons located in the spinal cord. Orlovsky et al (1960), reported there is an area in which, when stimulated lead mesensefalon running movement, called the mesencephalic locomotor region.
Basic rhythmic patterns of neural activity that lead to movement caused by intrinsic neurons in the central nervous system. So it can be said there is a movement central program. A central program is an expression of the neural circuits that produce a specific pattern of motor output that does not require afferent feedback, eg, contraction of muscles alternately pleksor-extensor during walking. Grillner and colleagues (1973) suggested that the central program located in the spinal cord (mainly in lamina IV and V). The program is also known as central pattern generators or neural oscillator. During locomotor movements, the neurons which is the origin of the tract rubrospinalis, vestibulospinal and reticulospinalis are in a rhythmically active state. A group of adrenergic neurons located in the locus ceruleus and the lower brain stem, sends axons to lumbo-sacral spinal cord. This group is suspected of neurons that mediates the action of mecencephalic locomotor region. Assenden information sent from the spinal cord to higher centers during movement. Spinocerebellar tract bring input to the cerebellum from muscle spindles, tendon organs and joint afferents. Dorsal Spinocerebellar tract neurons receiving afferent input from the muscle specific so easily influenced, while the ventral spinocerebellar tract receive input from the periphery is more diffuse and weaker so it is more difficult to influence. Both dorsal and ventral spinocerebellar tract neurons are in an active state (the wicked) during movement. The second tract spinocerebellar send different information to the cerebellum. Dorsal tract transmit information on muscle activity, whereas the ventral tract transmits information about active processes in the spinal cord (the generation of patterns of movement).
Efferent information has two important roles in the process of walking, the first one is to start the motor program from one phase to the next phase. During the walk there are two phases in the cycle are rare swing phase (swing phase) performed by the flexor muscles and the standing phase (phase snatce) conducted by the extensor muscles. Another role of afferent information during the process of running is opening and closing reflex pathway in various parts of the step cycle (step cycle). Stimulation at the top of the foot in the swing phase (flexion) adds leg flexion, as well as the stance phase (extension)
Source:
pict: http://www.mpiwg-berlin.mpg.de/en/research/projects/DeptII_Mayer_Walking
