Organization of Motor Function

• The spinal cord has a role in


  simple muscle reflexes
• The brain stem has a role in


  complicated responses
• The cerebrum has a role in


  the most complicated muscle skills
• Neuronal circuits for walking and various reflexes are contained within

  the spinal cord
• Sensory fibers enter the spinal cord and are transmitted to _______________, or they

  higher center or they synapse locally to elicit motor reflexes
• Motor neurons are located on the

  anterior portion of the cord
• What stimulates extramural muscle fibers collectively called motor units

  Alpha motor neurons
• What stimulates intramural fibers, in the muscle spindle, a special type of sensory receptor

  Gamma motor neurons
• What is more abundant than anterior motor neurons

  interneurons
• What are small and highly excitable

  interneurons
• most signals from the brain terminate on

  interneurons
• What is comprised of neural curcuitry for motor reflexes?

  interneurons
• What travels up and down the spinal cord for 1-2 segments and provide pathways for multisegment reflexes

  propriospinal fibers
• What makes up the bulk of muscle

  extrafusal fibers
• what is stimulated by alpha. motor neurons

  extrafusal fibers
• What provides force for. muscle contraction

  extrafusal fibers
• What are smaller than extramural fibers?


  intrafusal fibers
• What is encapsulated in sheaths to form muscle spindles


  intrafusal fibers
• what run-in parallel with extrafusal fibers but much shorter


  intrafusal fibers
• What is located in the muscle belly and sense muscle length and rate of change in length

  muscle spindle
• what is located in the tendon and senses tendon tension and rate of change in tension

  Golgi tendon organ
• signals from sensory muscle receptors are mainly for

  intrinsic muscle control and occur subconsciously
• Signals from sensory muscle receptors transmit information to

  the cerebrum, cerebellum, and the spinal cord
• what excites the muscle spindle

  sudden stretch of the muscle
• afferent impulses to the cord excite

  alpha motor neuron which results contraction of muscle
• What is the patellar reflex

  1. strike the knee

  2. muscle spindle stretches

  3. type Ia afferent stimulates alpha motor neuron in L4

  4. antagonistic flexor relaxes via inhibitory interneuron

  5. alpha motor neuron stimulates quadriceps to contract

  6. leg kicks
• What is a result of the absence or decrease the patellar reflex

  Westphal's sign
• What can cause Westphal's sign?

  receptor damage, peripheral nerve disease, lesion in motor cortex or pyramidal tracts, and interruption of sensory and or motor impulse transmission in femoral
• What are the three subarea of the motor cortex

  primary motor cortex, premotor area and supplemental motor area
• Fine motor movement is elicited by stimulation from the

  primary motor cortex area
• what controls the legs, feet, trunk, arm, hand, face, and mouth

  primary motor cortex
• The stimulation of what group results in the movement of muscle groups to perform specific task and works in concert with other motor areas

  premotor area
• The stimulation of this group often elicits bilateral movements


  supplemental motor area
• What functions in concert with the premotor area to provide attitudinal, fixation or positional movement for the body


  the supplemental motor area
• What provides the background for fine motor control of the arms and hands by the premotor and primary motor cortex


  supplemental motor area
• What controls word formation

  broca area
• Damage to Broca's area causes

  decreased speech capability
• What is also controlled in Broca's areas besides speech

  appropriate respiratory function for speech
• The eye fixation and head rotation area controls


  coordinated her and eye movements
• damage to the hand skills are causes

  motor apraxia