motor function/movement relies on the overall plan and constant sensory feedback through the
SENSORIMOTOR SYSTEM. ➞ output - motor cortex (left hemisphere section controls the
body's right side) 》input - sensory cortex (left hemisphere section receives input from the body's
right side) 🟆categories of movement🟆voluntary movements (under volitional control) -
purposeful, goal-directed movements • reflexes (automatic) - involuntary, stereotyped, rapid
movements • rhythmic motor patterns - repeating patterns of movement mediated by central
pattern generators (ex: respiration, walking) 🟆principles of motor function🟆 1. hierarchal
organization - association cortex at the highest level (complex processing), muscles at the
lowest (simple processing) 2. sensory feedback is essential - most motor output is guided by
sensory input 3. the motor system learns (motor learning) - the process by which motor
programs are created and modified; a learned, fixed sequence of movement 🟆muscle🟆skeletal
- approximately 40% of human body weight • cardiac - muscle in the heart; involuntary pumping
of blood • smooth - digestive system; involuntary digestion • sarcopenia - age related muscle
loss • flexors - bend a joint (i.e. biceps) • extensors - straightens a joint (i.e. triceps) 》
antagonistic= when two muscles cause opposite movements (i.e. biceps & triceps) •
synergistic= when two muscles contract and cause the same movement 🟆motor neuron &
motor unit in muscle🟆 motor unit - consists of a single motor neuron and the myofibers
(muscle tissues) muscle fibers it innervates (controls); all fibers in the same motor unit contract
when the motor neuron fires • motor pool - all of the motor units controlling the same muscle •
muscle fiber - there are fast muscle fibers + slow muscle fibers • innervation ratio - number of
muscle fibers per motor unit; determines movement precision 》low ratio/small motor unit =
precise movements • high ratio/large motor unit = coarse, less precise movements》
neuromuscular junction - the connection between the terminal end of a motor neuron and the
motor end-plate of the muscle fiber: action potential in motor neurons releases acetylcholine in
the terminal, causing muscle to contract 🟆proprioception🟆 proprioceptive system -
somatosensory subsystem; monitors information about the position of different parts of the
body; transmitted via specialized sensory receptors (proprioceptors) in muscle… 1. muscle
spindles - embedded in muscle tissue; respond to changes in muscle length • muscle-spindle
feedback circuit - muscle spindle: receptors and it's intrafusal muscle… the intrafusal muscle
is innervated by intrafusal motor neuron > the intratrafusal motor neurons adjust the length of
intrafusal muscle to maintain appropriate degree of muscle tension 2. golgi tendon organs -
embedded in tendons; respond to changes in muscle tension; protect muscle from being over
stretched🟆spinal circuits for reflexes🟆 reflex - a response to a stimulus that does not require
the involvement of consciousness 1. stretch reflex - occurs when the length of a muscle is
suddenly extended: automatically retracts in response to passive stretching (i.e. patellar
tendon/knee jerk reflex) i. monosynaptic reflex (only involves one synapse) ii. afferent neuron
brings sensory signal to spinal cord iii. efferent neuron sends motor command; muscle contracts
2. withdrawal reflex - occurs when you touch something painful; different from stretch reflex in
which the circuit is not monosynaptic; involves interneurons i. reciprocal innervation - some
sensory neurons excite excitatory interneurons, while some excite inhibitory interneurons i.e.
excitatory interneuron - contraction of bicep & i.e. inhibitory interneuron - relaxation of triceps 3.
recurrent collateral inhibition - a negative feedback loop that prevents rapid, repeated firing of
the same motor neuron i. motor neuron branches (collateral axon) onto interneuron (renshaw
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller emmaalfarone. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $8.39. You're not tied to anything after your purchase.
