Movement By: Isvita Marfatia
Introduction: What is movement? • Movement is the power to control each individual muscle throughout your body. • Movement is used for more than for mobility, it can display a persons mood from the persons body language down to something as little as a frown or a smile. • Through new neural experiences and connections our muscles learn to adapt to the surrounding environment and everyday life. ("Practice makes perfect!")
Examples of movement • Movement can range from • Involuntary • reflexes, food digestions, etc. • Voluntary • throwing a ball, writing, etc.
Muscles • They produce movement under the control of the brain and spinal cord • Skeletal muscles- muscles that attach to points on the skeleton and cross one or more joints
Muscles • Based on whether it is a joint flexor (closer) or an extensor (opener), muscles can be activated to open or close these joints that muscles span 1.) 2.)
Muscle Movement • “Stiffen” joints result from when a flexor and extensor joint are activated at the same joint. • Agonists- muscles that move a joint in an intended direction • Antagonists- muscles that move a joint in the opposed direction • Movements at high speeds are started by agonists and stopped by antagonists, so essentially the joint is placed in the proper position.
What was that again? • Muscles that move a joint in an intended direction are called agonists, • Muscles that oppose this direction of movement are antagonists.
Muscles Acting on Soft Tissue • These muscles move the eyes and tongue as well as control facial expression • They are under control of the central nervous system.
The Skeletal Muscle • It is made up of thousands of muscle fibers • A muscle fiber is controlled by alpha motor neurons that can be located in the brain or the spinalcord • An alpha motor neuron can control up to 100 or more muscle fibers • Motor units link the brain and muscles • The death of a motor neuron can disable a person's ability to move, whether it be voluntarily or via reflexes Alpha Motor Neuron Muscle Fibers Motor unit + =
Reflexes • What are reflexes? • They are fixed, automatic muscle responses to particular stimuli and involve the activation of small sensory receptors in the skin • For example, when a physician taps your muscle tendon at the knee, a slight muscle stretch occurs • The stretch is sensed by special receptors in the muscle called muscle spindles • These spindles then can send information about the speed and length of the stretch of the muscle to the spinal cord and eventually the brain • This information would afterwards be used in reflex control at the joint at which the muscle acts and for control of voluntary movements
Reflexes (Spinal Cord) • Muscle spindle fibers (receptors) transmit impulse to afferent neuron. • These fibers then activate motor neurons in the muscle causing a contraction called the stretch reflex • At the same time inactivation of motor neurons of antagonist muscles within the spinal cord occurs
Reflexes (Brain) • The brain controls the sensitivity of muscle spindle organs via gamma motor neurons, which control the specialized muscle fibers • The brain can also sense and control the muscular force exerted during movement through the golgi tendon organs, which are specialized sense organs in the muscle tendon that detect the force applied by a contracting muscle
Flexion Withdrawal • Occurs when your bare foot steps on a sharp object • In response, your leg immediately lifts from the sharp object (an action called the flexion) and your other leg responds by extending a little so you can maintain your balance (an action called the crossed extension reflex)
The Motor Cortex & the Basal Ganglia • The motor cortex exerts powerful control over the spinal cord via direct control of its alpha motor neurons • The basal ganglia has connections with the motor and sensory areas of the cerebral cortex • Dysfunction of the basal ganglia can lead to tremors, rigidity, and akinesia of Parkinson’s disease • Dopamine is supplied to the basal ganglia by the axons of neurons in the substanianigra, which is a midbrain cell group
The Cerebellum • It is crucial for coordinating and adjusting skilled movement • Problems with cerebullar function can cause poor coordination of muscle control, disorders of balance and reaching, and even difficulties in speech • The cerebellum helps us adjust motor output to deal with changing condition (growth, disability, changes in weight, and aging) • Our ability to talk, speak, and do the necessary is stored as detailed control information within the cerebullum
More Complex Movements • there are networks of spinal neurons responsible for movement • maintain posture • walking • To a large degree, all movements really. • Spinal Mechanisms such the coordination of walking are being studied to find the correct spinal circuitry used to recover basic postural and locomotor function after severe paralysis.
Complex Movement • voluntary movement is mostly controlled by the motor cortex and the spinal cord • neurons in the motor cortex • specify the coordination of many muscles for limb control • others control over two to three functionally connected muscles for skilled movements.
Helpers • Movement control involves the interaction with many other brain regions: • Mostly Midbrain and Brainstem: • These regions send axons to the spinal cord. • Basal ganglia • Thalamus • Cerebellum
Dysfunction of the Basal Ganglia • Leads to SERIOUS movement disorders. • The neurotransmitter, dopamine is supplied to the basal ganglia via the substantianigra, a midbrain cell group. • Parkinson’s disease deals with degeneration of the nigral neurons. • As a result, the dopamine supply is not longer being supplied to the basal ganglia, which results in tremor, rigidity, akinesia, the inability to move.
Complex Movement • parkinson's disease occurs when the nigra neurons degenerated. • the body no longer gets the supply of dopamine and gets the symptoms of parkinson's • Tremors • Rigidity • Akinesia (inability to move)
The Cerebellum • Crucial for coordinating and adjusting skill movement. • A disturbance in cerebellar function leads to poor muscle movement, disorders of balance and reaching, and difficulties in speech.
More on the Cerebellum! • The cerebellum receives direct information from all the sensory receptors in the head and the limbs and from most areas of the cerebral cortex. • Will ensure smooth coordination of muscle movements. • This enables us to do skilled movements more or less automatically.
The Cerebellum • Adjusts motor output to deal with changing conditions: • Growth, Disability, Changes in weight, and Aging. • Have you ever picked up a coffee cup where you were unaware how full it was? • The Cerebellum helped you adjust to that. • Detailed Control Info. Is stored in the cerebellum • Walking • Speaking • Playing a musical instrument
Review • Learned skills are stored in _____? • Cerebellum • 3 symptoms of Parkinson’s disease? • Tremors, rigidity, immobility • What causes Parkinson’s disease? • Degeneration of nigra neurons • What do nigra neurons do? • Release dopamine • What parts of the brain send axons to the spinal cord? • Midbrain brainstem. • 5 parts of brain involved in movement. • Thalamus • Cerebellum • Midbrain • Brainstem • Basal Ganglia
Activity: How Fast Are You? Get a ruler (or a yardstick or candy bar). Hold the ruler near the end (highest number) and let it hang down. Have another person put his or her hand at the bottom of the ruler and have them ready to grab the ruler (however, they should not be touching the ruler). Tell the other person that you will drop the ruler sometime within the next 5 seconds and that they are supposed to catch the ruler as fast as they can after it is dropped. Record the level (inches or centimeters) at which they catch the ruler (you can convert the distance into reaction time with the chart below). Test the same person 3 to 5 times (vary the time of dropping the ruler within the 5 second "drop-zone" so the other person cannot guess when you will drop the ruler).
Equations: Formula 1 provides you with the distance an object will fall in a given amount of time. By rearranging Formula 1 into Formula 2, you can get the amount of time it takes an object to fall a certain distance...that's what you want to find out. All you have to do is plug in the distance (in either centimeters or inches) that the ruler fell into Formula 2 - this will give you the reaction time. In the formulas, t = time (in seconds); y = distance (in cm); g = 980 cm/sec2 (acceleration due to gravity). [Note: you can also use inches in your distance measurement, but you must change g to equal 385.8 in/sec2.]