3/19/14
Muscles - ~640 muscles; divisions based on microscopic morphology: striated/skeletal muscles (attached to bones and allow voluntary movement); smooth muscles (glands and organs); cardiac muscle (intermediary of other two, heart muscles)
	Striated muscles – divided into flexor muscles (closing joint) and extensor muscles (opening joint); also divided into fast twitch and slow twitch which are types of muscle fibers which are combined in a muscle 
Proprioceptors – monitoring state and position of muscles:
	Muscle spindle – receptors which connect from tendon to tendon within a muscle and measure the amount of stretch on the muscle; muscle spindles contract along with muscle fibers (have both motor input and sensory input
	Golgi tendon organ – located in tendon and measure stretch in tendon
	Joint receptor – located in joint and measure the position of the joint
Neuro-muscular junction: Ach synapse causes contraction of skeletal muscle
Cranial motor neurons and spinal motor neurons
Lower motor neurons – lower motor neuron disease is a problem in spinal cord; upper motor neuron disease affects something in brain
Final common pathway – only one way to get a signal to the muscle is through the specific set of axons that leave the spinal cord; so the axons that innervate muscles are called the final common pathway; information is funneled into a small number of neurons 
Upper motor neurons and pathways:
	Corticospinal tract – from cortex to spinal cord; aka pyramidal tract; goes to base of pons (or medulla?) (crosses at decussation of the pyramids) then to spinal cord; flexor bias in terms of motor pool; primarily innervates forelimbs, especially fingers and hands; monkeys with damage lose ability to control fingers individually but not ability to pick things up completely; flexors are primarily used for fine motor activities
	Corticorubral spinal tract – similar to above with intermediate step in red nucleus of midbrain; generally flexor bias and goes to forelimbs as well; allows more systems to send information
	Tectospinal tract – from tectum (superior/inferior colliculus location) to cortex; involved in innervating shoulder and trunk muscles in order to orient position in space (in response to stimuli sometimes based on superior colliculus)
	Vestibulospinal tract – begins in vestibular nuclei of brainstem; involved in extensors
	Reticulospinal tract – from reticular formation; involved in wakefulness/consciousness and matches muscle tone in spinal cord/trunk to brain state; does not have fine control; 
 Dorsolateral motor pathways – corticospinal and corticorubral; information from contralateral side
Ventromedial motor pathways – tectospinal, vestibulospinal, reticulospinal  
Process motor information but do not send information down spinal cord
Cerebellum – purkinje cells are in one plane with extreme dendritic branching; parallel fibers are perpendicular to purkinje; clibing fiber connects to cell body of purkinje; system measures coincidence of signals;
Basal Ganglia – substantia nigra; globus pallidus; caudate; putamen