Exam 1 Flashcards
alpha motor neuron
- project to extrafusal skeletal muscle
- ALWAYS LMN - from synapse to muscle
- have large cell bodies & large myelinated axons
- release enough ACh that all muscle fibers it innervates contract
gamma motor neuron
- project to intrafusal fibers of muscle spindle
- have medium-sized myelinated axons
muscle spindle
type 1a
GTO
type 1b
presynaptic inhibition
STOPPING A REFLEX: Conscious thought – volition – CNS from brain – Corticospinal tract – presynaptic inhibition to stretch reflex arc by causing hyperpolarization & releases NT GABA (inhibitor) = UMN
Voluntary movement
- Corticospinal tract - UMN
- Initiated in response to something in the environment
- Purposeful, meaningful, and goal directed
- Learned automatic movements like writing or keyboarding
Reflex movement
Rapid and involuntary
Central pattern generation
- Interconnection of neurons that produce rhythmic movements like walking and chewing
- These movements are typical to the individual but may vary across subjects
Coordinated movement
-Coordinated movement requires agonist and antagonist movements for both static and dynamic adjustments
-Examples: sitting posture and reaching
-Sensory Information:
Exteroceptors are the representation of the spatial coordinates or self, objects, and the environment
-In order to coordinate movement a variety of proprioceptive and spatial information is needed depending on the activity being performed
Refine movement
Basal ganglia & cerebellum
afferent to efferent process
Afferent –> thalamus –> parietal (primary somatosensory) –> cortex –> corticospinal (UMN) –> refined by basal ganglia & cerebelum –> spinal cord –> muscle
Feedback
- closed loop model (input, error, instructions, output, feedback)
- Correct via feedback from proprioception, touch, etc. to tighten grip in slippery water bottle
Feedforward
- Open control (input, instructions, output)
- Input from gustatory receptors says I’m thirsty & brain decides to pick up glass
- Feedforward is faster – not relying on any feedback info
Control of Movement
- Top-down (brain to spinal cord to muscle)
- Motor neurons: control skeletal muscles
- LMN: innervate skeletal muscles
- UMN: descending tract
- Control circuits: Basal ganglia and Cerebellum
Upper Motor Neurons
Descending tracts:
- Postural/gross movement tracts
- Fine movement & limb flexion tracts
- Non-specific UMN
ATP
A common form in which energy is stored in living systems; consists of a nucleotide (with ribose sugar) with three phosphate groups. The energy coin of the cell
SMA
- Supplementary Motor Area LOCATION: - Medial portion of Broadman’s area 6 FUNCTION: - Initiation of movement, orientation of eyes & head, planning bimanual & U/L sequential movements CONNECTION: - Thalamic input from ventral anterior nucleus - Send to the primary motor area - Basal Ganglia - Brainstem - Spinal Cord
PMA
- Pre-Motor Area LOCATION: - Broadman's area - Anterior to the primary motor cortex FUNCTION: - Controls trunk & girdle muscles via medial UMN CONNECTION: - Thalamus - Basal ganglia - Brainstem - Spinal cord
M1
– Area 4 or primary motor cortex
LOCATION:
- Precentral gyrus Broadman’s area 4
FUNCTION:
- Responsible for the execution of skilled movements
- Generates individual muscle movements as well as movements that cross joint
- Responsible for directing the amount of force needed by a muscle or for a movement
CONNECTIONS:
- Receives information form the thalamus ventral lateral nucleus
- Sends to ‘higher order motor areas
-Premotor cortex
-Basal ganglia
-Cerebellum
ORGANIZATION:
- Somatotopical organization of the entire body
- Represents 30% of the corticospinal tract
S1
– Primary Sensory Cortex
Dorsolateral Prefrontal Cortex
– front side portion of prefrontal cortex
- executive functioning
Cingulate Motor Area
LOCATION: - Cingulate gyrus - Medial portion of the cerebral cortex - Broadman’s area 24 and 6 FUNCTION: - Mediates emotional movements - Considered part of the limbic system CONNECTIONS: - Receives from the amygdala - Communicates though the basal ganglia to mediate motor movements
Lesions to M1
- Hemiplegia
- Contralateral weakness
- Impaired postural righting and equilibrium reactions
Lesions to PM
Uncoordinated clumsy movement
Lesions to SMA
- Inability to initiate movement
- Overall lack of movement referred to as akinesia
- Apraxia or difficulty with motor planning
Medial UMNs
- medial white columns; postural + girdle
- 4 tracts:
Tectospinal
Medial Reticulospinal
Medial & Lateral Vestibulospinal
Medial Corticospinal - All tracts are more Automatic
Lateral UMNs
- lateral white columns; distal/fine movt.
- 3 tracts:
Lateral Corticopinal
Rubrospinal
Lateral reticulopsinal - Limb flexion
- Fine movements of the limbs
Non-specific UMNs
- throughout ventral columns;
background excitation + local reflex arcs - 2 tracts
Ceruleospinal
Raphespinal - Enhance activity of interneurons and motor neurons in spinal cord
- Emotional motor system
Medial corticospinal
- straight down from motor cortex – runs near midline
- (15% of the pyramidal tract):
- Voluntary movement, primarily of the neck, shoulder & trunk muscles
Lateral vestibulospinal
vestibular nucleus in medulla down to spin – regulates more automatic mvmt
- Vestibulospinal - Positioning and movement of the body and head, muscle tone, maintain center of gravity over base of support
Tectospinal
– tectum of midbrain (4 colliculi = bumps) – superior colliculi, crosses in midbrain, down to spine
- Reflexive response to visual and auditory stimuli
Medial reticulospinal
– reticular activating system of pons to spine
- General positioning (trunk/postural muscles + extensors) and muscle tone
Medial vestibulospinal
– vestibular nucleu, crosses in medulla, down to spine
- Vestibulospinal - Positioning and movement of the body and head, muscle tone, maintain center of gravity over base of support
Lateral Corticospinal
- (85% of the pyramidal tract):
- Voluntary movement, primarily of the extremities,
- Fractionation/individuation of movement (individual finger movement, in hand manipulation)
Rubrospinal
Voluntary movement of trunk and limbs
Lateral Reticulospinal
+ flexor motor neurons (excites)
- extensor motor neurons except walking (inhibits)
Corticobulbar tracts
- (bulbar = brainstem)
- Motor cortex –> Cranial nerve nuclei in brainstem
- Muscles of face, tongue, pharnyx and larnyx, trapezius, sternocleidomastoid
- Upper face: bilateral innervation
- Lower face: contralateral innervation
- Accessory nerve, glossopharyngeal, etc.
Diaschisis
loss of function of neurons in CNS distant to the injury (Christmas tree lights)
preganglionic
- Considered First order
- Cell body in the CNS
- Thinly myelinated
- Uses acetylcholine
postganglionic
- Considered Second order
- Cell body in the PNS
- Unmyelinated
- Uses acetylcholine in the PSNS and norepinephrine in the SNS (except sweat glands which used Ach)
Paravertebral ganglia
- They are located along side the vertebral column form T1 to L2
- Arranged as a chain “ANS chain”
- Functionally is the sympathetic NS
Prevertebral ganglia
- This category is located distal to the CNS in the abdomen
- Innervates the thoracic and lumbar regions
- Functionally has a combination of sympathetic and parasympathetic synapses
Intrinsic ganglia
- Located distal to the CNS
- Near Organs
- Parasympathetic
- Originates from S2-to S4
- Cranial nerve X
Cranial ganglia
- Located in the head
- Parasympathetic
- Cranial nerve III, VII, IX
- Occular motor
- Facial – lacrimal
- Glossopharyngeal – parotid gland
Autonomic Fiber Pathways by Division: Sympathetic
- Sympathetic (T1 to L2)
- These fibers originate in the lateral horn of the gray matter
- They exit the spinal cord through the ventral root
- These are the fibers that branch off from the spinal nerves
- The branching area where they travel is called the white communicating ramus
- They enter the paravertebral ganglion
White communicating ramus
– preganglionic
Gray communicating ramus
– postganglionic
SympatheticNervous System
- Arousal
- Fight / Flight
- Increased Blood Pressure
- Increased Heart Rate
- Cessation Peristalsis
Sympathetic Fibers
- Synapse
- Travel though the chain
- make additional connections
- Exit to their corresponding targets
Parasympathetic Nervous System
- Homeostasis
- Heart rate
- Respiration
- Metabolism
- Digestion
- Slowing Body Down
- Decreased Blood Pressure
- Decreases Heart Rate
- Peristalsis
Reticular formation
- of the brainstem - plays a role in some autonomic responses:
- Vasopressor & Vasodilation
- Cardiac acceleration & deceleration
- Respiratory responses
Sympathetic (ganglia)
- Thoracolumbar region
- Ganglia close to the spinal cord
- Myelinated short preganglionic
- ACH - preganglionic
- Unmyelinated long postganglionic
- Norepinephrine - postganglionic
- Specific or diffuse
- Long effects - minutes
Parasympathetic
- Cranial and sacral
- Ganglia located near the target
- Preganglionic myelinated long
- Preganglionic - ACH
- Postganglionic unmyelinated short
- ACH - postganglionic
- Specific
- Short effects - seconds
Regrowth after transection and repair
- 1.08 mm/day pain fibers
- 0.78 mm/day touch fibers
Spindles contain 2 types of fibers:
nuclear bag & chain
Nuclear chain
– length
Nuclear bag
– length & velocity
1a
– heavily myelinated – respond to velocity of stretch – faster
2
– unmyelinated, medium in size
Golgi Tendon Organs
- Found in tendons
- Detects tension and sends message for adjustment of muscle tension
- Activation of golgi tendon organs results in inhibition of contraction of that muscle
Therapeutic use of GTO
- Slow sustained stretch – reduce spasticity by inhibit agonist and facilitate antagonist
- Sustained pressure on tendon – reduce spasticity
- Splinting provides slow sustained stretch
- Serial casting provides slow sustained stretch
- Positioning techniques (In NDT reflex inhibiting postures)
Joint Receptors
- Numerous types of receptors in joint capsule and ligaments
- Ruffini’s endings (signal end of joint range – respond more to passive mvmt than active mvmt)
- Paciniform corpuscles
- Ligament receptors
- Free nerve endings (pain, temp, inflammation)
- Signal end range, movement, and pain in joint.
- Information sent to
- spinal cord (provide prop. info to motor neuron)
- cerebellum
Algesia
– sensitivity to pain
Breakthrough pain
– chronic pain, have spike in pain
Hyperalgesia
– extreme sensitivity
Idiopathic pain
– unknown cause
Intractable pain
– doesn’t respond to treatment - chronic
Pain threshold
– point at which stimulus will cause you pain
Pain tolerance
– how much pain you can take
Pain syndrome
– multidisciplinary approach, chronic pain
Phantom limb pain
– amputees but still feel pain
Psychogenic pain
– pain psychological of nature
Radiating pain
– spreads out from original site
Referred pain
– pain in diff. location from where it is
Antinociception
- (pain suppression)
- Chemical or physical intervention at different places along the pain pathway
- Pain pathway
- Peripheral receptors
- Dorsal horn of spinal cord
- Brainstem
- Amygdala, thalamus, hypothalamus
- Cerebral cortex
A delta
– thinly myelinated – high velocity – high pain, sharp pain
-Fast pain – quicker
C fibers
– unmyelinated – low velocity
- Slow chronic pain
Pain pathways
-Spinothalamic
-Ascending
-Dorsal horn to thalamus
-Reticulospinal
-Descending
-Brainstem to spinal
-Trigeminothalamic
-Ascending
-CN5 to thalamus
-Spinotectal
– superior & inferior colliculus
– turn toward pain (inferior auditory, superior visual)
-Reticular formation
– like your main switch
– makes active
– shuts off when go to sleep
-Postcentral gyrus
– analysis of the pain, localization of pain, what kind of pain
-Cingulate gyrus
– emotional part of pain
-Insula
– autnomic responses
– sweating, nauseousness, etc.
-Trigeminothalamic
– a separate pathway from CN5
– ascending
– areas trigeminal nerve innervates in face
How the body modulates pain
- Endorphins
- Stress
- Distraction
Gate control theory of pain
-With pain stimulation: small nerve fibers become active. They activate P & block II. B/c activitiy of I is blocked, it cannot block the output of P that connect w/ the brain. The “gate is open” therefore, PAIN!!
Counterirritant theory of Pain suppression in dorsal horn
- Rubbing or pressure releases enkephalin (neurotransmitter) in dorsal horn
- Enkephalin binds with afferent nerves carrying nocioceptive information
- Causes substance P release to be depressed resulting in hyerpolorization of the neuron and inhibition of the pain signal
Neuropathic pain
Caused by:
- Mechanical compression or lesion of nerves
- E.g. carpal tunnel, peripheral nerve injury
- Demyelination
- Ectopic foci
- Ephaptic transmission
- Central sensitization
- Over activity of central neurons lasting beyond initial injury due to neuroplastic changes
- Structural reorganization of the neurons
- Chemical disruptions (neurotransmitters, hormones, and enzymes)
Complex Regional Pain Syndrome
- Aberrant response to trauma
- After trauma (often minor)
- Usually distal extremity
- May occur soon after or weeks later
- Signs and symptoms:
- Sensory
- Severe spontaneous pain
- intensified by skin contact, heat, & cold
- Motor
- May have paresis, spasms & tremor; muscle atrophy
- Autonomic
- Abnormal sweating, vasodilation in skin, atrophy (due to blood flow changes and disuse) of muscles, joints & skin
How the body modulates pain
- Endorphins
- Stress
- Distraction
Gate control theory of pain
-With pain stimulation: small nerve fibers become active. They activate P & block II. B/c activitiy of I is blocked, it cannot block the output of P that connect w/ the brain. The “gate is open” therefore, PAIN!!
Counterirritant theory of Pain suppression in dorsal horn
- Rubbing or pressure releases enkephalin (neurotransmitter) in dorsal horn
- Enkephalin binds with afferent nerves carrying nocioceptive information
- Causes substance P release to be depressed resulting in hyerpolorization of the neuron and inhibition of the pain signal
Neuropathic pain
Caused by:
- Mechanical compression or lesion of nerves
- E.g. carpal tunnel, peripheral nerve injury
- Demyelination
- Ectopic foci
- Ephaptic transmission
- Central sensitization
- Over activity of central neurons lasting beyond initial injury due to neuroplastic changes
- Structural reorganization of the neurons
- Chemical disruptions (neurotransmitters, hormones, and enzymes)
Complex Regional Pain Syndrome
- Aberrant response to trauma
- After trauma (often minor)
- Usually distal extremity
- May occur soon after or weeks later
- Signs and symptoms:
- Sensory
- Severe spontaneous pain
- intensified by skin contact, heat, & cold
- Motor
- May have paresis, spasms & tremor; muscle atrophy
- Autonomic
- Abnormal sweating, vasodilation in skin, atrophy (due to blood flow changes and disuse) of muscles, joints & skin
Lateral horn only present at:
- T1 – L2 sympathetic & S2-S4 parasympathetic
