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CHAPTER 11. The Body Senses and Movement The Body Senses Movement. Movement. Skeletal muscles move the body and limbs. Are called striated muscles: have striped appearance. Smooth muscles produce the movements of the internal organs.

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Chapter 11


The Body Senses and Movement

The Body Senses



  • Skeletal muscles

    • move the body and limbs.

    • Are called striated muscles: have striped appearance.

  • Smooth muscles

    • produce the movements of the internal organs.

    • E.g., Cardiac muscles are the muscles that make up the heart.

Movement basal ganglia cerebellum


  • Muscle: made up individual cells: Muscle fibers.

    • Muscle fiber made up of

      • myosin filaments

      • actin filaments.

    • controlled by motor neurons

    • Motor neurons synapse with muscle cell at the neuromuscular junction.

  • When a motor neuron releases acetylcholine:

    • Muscle fiber is depolarized,opens calcium (Ca+) channels.

    • Calcium influx initiates a series of actions by the myosin

    • result  contract the muscle.

Movement basal ganglia cerebellum


  • Muscle Contractions:

    • Myosin filaments climbs along surrounding actin filaments

    • Movements of myosin filaments relative to actin filaments shortens fibers and contracts muscles

  • Skeleletal muscles anchored to bones by tendons

    • Tedons = bands of connective tissue

    • Movement of tendons operates bones like levers

    • Use antagonistic muscles

Movement basal ganglia cerebellum

Antagonistic muscles

  • Antagonistic muscles

    • muscles that produce opposite movements at a joint.

    • E.g., the bicep muscle

      • flexes the arm

      • the triceps extends it.

  • Simultaneous activation of antagonistic muscles contributes to:

    • smoother movements,

    • precise stopping

    • reduction of tremor.

Movement basal ganglia cerebellum

Spinal cord modulation of Muscle Movement

  • Several specialized receptors for movement in spinal cord

  • Spinal Reflex

    • Movement of muscle detected by muscle stretch receptor

    • Muscle spindles = Muscle stretch receptors

    • Relay this info to spinal cord

    • Sensory neurons synapse on motor neurons

    • Motor neurons then return to muscle, cause it to contract

  • may be located in the spinal cord or brain.

Movement basal ganglia cerebellum

Spinal cord modulation of Muscle Movement

  • Golgi tendon organs

    • receptors that detect tension in a muscle.

    • Trigger spinal reflex that inhibits muscle

    • Prevents muscle from contracting too much, avoids damage

  • Central pattern generators

    • neuronal networks: form neural circuit for complex pattern of behavior

    • produce rhythmic patterns of motor activity,

      • E.g., walking, swimming, flying, and breathing.

    • Central pattern generators may be located in the spinal cord or brain.

    • May be observed in young children: “walking reflex”

    • Showing an infantile reflex in adulthood is good indication of brain or spinal cord injury!

Movement basal ganglia cerebellum

Motor cortices

  • Hierarchical organization:

    • Forebrain

    • Brain stem

    • Spinal cord

  • The motor cortex consists of:

    • primary motor cortex

    • two major secondary motor areas:

      • supplementary motor area

      • premotor cortex.

  • Both primary and secondary area contain a map of the body

    • Motor Homunculus

    • greater amounts of cortex devoted to the parts of the body that produce finer movements.

Movement basal ganglia cerebellum

Prefrontal cortex

  • Serves as initial step in motor planning

  • Plans actions with regard to consequences

    • Receives info from ventral visual stream about object identity- used to identify target of motor activity

    • integrates auditory and visual information about the world with information about the body

    • Body information comes from posterior parietal cortex

  • Prefrontal cortex appears to hold information in memory while selecting appropriate movement and its target.

Movement basal ganglia cerebellum

Prefrontal cortex

  • Tests examining prefrontal cortex control include:

    • Delayed matching to sample

      • Show a stimulus and then a stimulus array

      • Must choose the stimulus you saw from that array

    • When sample presented: cells in prefrontal cortex start to fire

    • Continue to fire during delay

    • When begin response: second group of prefrontal cell start firing

    • Thus: “remembers” sample, then when respond, this shuts down

  • Important for planning and executing complex behavior

Movement basal ganglia cerebellum

Premotor cortex

  • This area controls initiation/programming a movement

  • combines information from the prefrontal cortex and the posterior parietal cortex.

  • Show function via rubber-hand illusion

    • Person sits at table with left hand hidden

    • Experiment strokes hidden left hand with brush

    • Experimenter simultaneously strokes rubber hand that is in full view

    • Subject reports that the sensation seems to come from rubber hand, not their own

    • Why?: Stimulated premotor cortex when receive simultaneous and corroborative input from sensory AND visual stimuli

Movement basal ganglia cerebellum

Supplementary motor area

  • Output from the prefrontal cortex flows to supplementary motor area (SMA)

  • assembles sequences of movements

  • Critical for integrating information from both sides of body

    • Bilateral integration

    • Ability to cross midline

    • E.g., eating or playing the piano

  • Damage to SMA results in inability to carry out alternating tasks.

Movement basal ganglia cerebellum

Primary motor cortex

  • Responsible for execution of voluntary movements

    • cells fire most during the movement instead of prior to it.

    • Individual cells here not for specific movement, but contributes function to range of related behaviors

  • Coordinates activity of cells into useful movement

    • Contributes control of movements’ force and direction

  • Must have input from

    • Secondary motor areas

    • Somatosensory cortex

    • Posterior parietal area

    • Sensory areas provide feedback for the motor movement

Movement basal ganglia cerebellum

Basal ganglia

  • Basal ganglia – includes:

    • The Striatum: putamenand caudate nucleus

    • Globuspallidus:

      • external segment of the globuspallidus(GPe),

      • Internal segment of the globuspallidus(GPi),

    • Subthalamic nuclei (STN),

    • Substantianigra(SN).

      • substantianigra pars compacta (SNc)

      • substantianigra pars reticulate (SNr).

  • Basal ganglia uses information from

    • Primary motor cortex

    • secondary motor areas

    • somatosensory cortex

Movement basal ganglia cerebellum

Basal ganglia send output directly to

primary motor cortex

supplementary motor area

premotor cortex

Sent via the thalamus.

Basal ganglia smooth movements by

facilitating outputs to thalamus

inhibiting outputs to the thalamus

Especially active during complex movement sequences

Involved in learning about motor sequences

Damage to Basal Ganglia results in inability to stop/start movement

Inability to learn motor sequences

Two major pathways:

direct and indirect pathways

have opposite net effects on their thalamic target structures:

Basal ganglia

Movement basal ganglia cerebellum

Direct vs. indirect Pathway

  • The direct pathway

    • makes excitatory connections on the thalamic neurons,

    • Thalamic neurons in turn make excitatory connections onto neurons in motor and cognitive areas of the cortex.

  • Indirect pathway

    • produces the net effect of inhibiting thalamic neurons.

    • When inhibited, thalamic neurons then unable to excite motor cortex neurons.

  • Within normally functioning basal ganglia, a proper balance is achieved between these two pathways.

Movement basal ganglia cerebellum

Basal ganglia

  • Delicate balance must be formed

    • direct pathway selectively facilitates a particular motor /cognitive behavior that is necessary for a present task,

    • Indirect pathway simultaneously inhibits neurons which control competing motor behaviors.

  • Extra pyramidal syndrome:

    • Upsetting the balance between these two motor pathways

    • Results in motor dysfunctions

    • Symptoms include stationary tremor, uncontrollable limb movements, difficulty walking and poor motor control

    • Parkinsons, Tardive Dyskinesia and related disorders

Movement basal ganglia cerebellum


  • Cerebellum

    • receives information from the motor cortex about an intended movement

    • determines the order of muscular contractions and their precise timing.

  • Cerebellum also uses information from the vestibular system to

    • maintain posture and balance

    • refine movements

    • control eye movements that compensate for head movements

Movement basal ganglia cerebellum


  • Cerebellum composed of two control loops

    • critical for controlling and processing motor behavior

    • Output loop

    • Feedback input loop

  • Cerebellum functions:

    • improves accuracy of movements

    • creates smooth muscle movements

    • Does this by comparing descending motor commands with information regarding current motor actions.

  • Cerebellar system makes corrections as necessary to equate current with desired motor sequences,

    • acting on the brain stem and cortical motor areas.

Movement basal ganglia cerebellum


  • Because cerebellum receives input from most body senses:

    • serves as distinct feed-back loop for sensory-motor coordination

    • Without feedback, poor or no coordinated movement

  • Cerebellum can be said to compare what the body is doing to what should the body be doing

    • and signals the brain to make changes as necessary.

  • Damage to the cerebellum typically results in

    • loss of ability for both sensory and motor coordination

    • Results in disruptions of equilibrium, motor coordination and postural control.

Movement basal ganglia cerebellum

Divisions of the cerebellum

  • The cerebellum divided into three zones

    • the flocculondular lobe

    • the anterior lobe (rostral to the primary fissure)

    • the posterior lobe (dorsal to the primary fissure).

  • Vestibulocerebellum

    • is composed of flocculondular lobe and the portion of the vermis immediately adjacent to the flocculondular lobe.

    • This area regulates both balance and eye movements.

    • Controls compensatory eye movements, shift gaze

  • damage to the vestibulocerebellum results in

    • disruptions of balance and gait.

    • Inability to shift gaze with movement

Movement basal ganglia cerebellum


  • Spinocerebellum includes

    • both the vermis and middle parts of the cerebellar hemisphere, or paravermis.

    • mediates body and limb movements.

    • critical for modulation of the descending motor systems.

  • Role: elaborate proprioceptive input, allowing the system to anticipate future body position.

    • Spinocerebellum anticipates and adjusts for movement.

    • Damage = delayed or no compensation in eye movement or body movement with change in body position

Movement basal ganglia cerebellum

Cerebrocerebellum and cerebellar deep nuclei

  • Cerebrocerebellum:

    • formed fromlateral hemispheres of the cerebellum

    • Critical for planning movement and evaluating sensory information required for action.

    • Plays critical role for planning anticipated motor movements and modulating at least some cognitive functions.

    • Frees up higher brain areas for higher cognitive functions

  • Cerebellar deep nuclei:unique (and only) set of output structures

    • embedded within center of each cerebellar hemisphere.

    • encased in highly convoluted tissue layers called the cerebellar cortex.

    • send outputs to

      • the superior and inferior cerebellar peduncles

      • on to various areas of the cerebral cortex.

Movement basal ganglia cerebellum


  • Prefrontal cortex: Selects appropriate behavior and target

  • Premotor cortex: Combines info for needed movement programming

  • Supplementary motor area: Assembles sequences of movements

  • Primary motor cortex: Executes voluntary movement

    • Adds control of force and direction

  • Basal Ganglia: Integrates info from secondary areas and somatosensory cortex creating smooth and integrated movement

    • Involved in learning motor sequences

  • Cerebellum: Maintains balance and refines movements

    • Controls compensatory eye movements

    • Involved in learning motor skills