Exam 1 Prep Flashcards
What are the principle roles of the nervous system?
-Cognitive functions
-Sensory-motor functions
-Motivation and emotion
-Regulatory function and homeostasis (autonomic NS)
What is the soma?
Cell body of the neuron
What is the axon hillock?
The initial segment of the axon
What is the axon?
Where the action potential travels through
What are the nodes of ranvier?
Where there is a gap in the myelin sheath surrounding the axon which allows the action potential to travel down the neuron
What is a dendrite?
A branch off of the cell body and is the site of synapses
What are the different types of neurons?
-Bipolar
-Motor neuron (multipolar)
-Sensory neuron (unipolar)
-Interneuron (multipolar)
What is white matter?
Groups of myelinated axons
What is gray matter?
Groups of cell bodies
What are fasciculi?
White matter pathways or tracts
What is a nucleus?
A group of functionally related nerve cells
What is a ganglia?
Group of multiple nerve cells
What are columns/tracts?
Occurs in the cerebral cortex and spinal cord and is a group of nerve cell bodies and their axons that are related in function
What comprises the central nervous system?
-Brain
-Spinal cord
What comprises the peripheral nervous system?
-Autonomic nervous system
-Peripheral nerves
-Cranial nerves
What are the components of the autonomic nervous system?
-Parasympathetic (“rest and digest”)
-Sympathetic (“fight or flight”)
What is the posterior root ganglion?
A group of nerve cell bodies lying in a peripheral nerve root
What is a root/ramus?
A peripheral structure with parallel axons
What part of the nervous system does the polio virus attack?
The polio virus attacks the anterior horn cell
Is the anterior horn cell considered to be apart of the PNS or CNS?
PNS
What nerve roots are associated with the parasympathetic nervous system?
-Cranial nerves
-Sacral nerves
What nerve roots are associated with the sympathetic nervous system?
-Thoracic nerves
-Lumbar nerves
How does the parasympathetic system effect the body?
-Constricts pupils
-Stimulates saliva
-Slows heartbeat
-Constricts airways
-Stimulates activity of stomach
-Inhibits release of glucose
-Stimulates bladder
-Stimulates activity of intestines
-Promotes erection of genitals
How does the sympathetic system effect the body?
-Dilates pupils
-Inhibits salivation
-Increases heartbeat
-Relaxes airways
-Inhibits activity of stomach
-Stimulates release of glucose
-Inhibits gallbladder
-Inhibits activity of intestines
-Relaxes bladder
-Release of epinephrine and norepinephrine
-Promotes ejaculation and vaginal contraction
What are the four types of brain/glial cells?
-Astrocytes
-Oligodendrocytes
-Ependymal cells
-Microglial cells
What are astrocytes?
-“star”
-Direct role in signaling
-Provides nutrition for neurons
-Involved in memory
-Release neurotransmitters (glutamate)
-Make up 30-65% of glial cells
What are oligodendrocytes?
They provide myelin in the CNS
What are ependymal cells?
-Cells that produce cerebrospinal fluid
-Provide waste clearance
What are microglial cells?
-Function as the immune cells in the NS
-Activated in nervous system diseases, infection, or injury
-Dying neurons secrete proteins that attract microglia
What cells are activated by neuroinflammation?
Microglia and astrocytes
What diseases is abnormal glial activity seen in? What happens to the microglia?
-Alzheimer’s
-Multiple sclerosis
-Parkinson’s disease
-Head injury
-Microglia lose their protective control and stimulate cellular breakdown
What are Schwann cells?
-Surround axons in PNS
-Responsible for myelination in PNS
-Participate in repair process after injury
What are satellite cells?
-Surround neuron cell bodies in ganglia
-Regulate O2, CO2, nutrient, and neurotransmitter levels around neurons in ganglia
What occurs during multiple sclerosis?
-The microglia attack the oligodendrocytes in the CNS
-This causes destruction of myelin which results in plaques (neuronal death)
What type of exercise helps the microglia to regenerate oligodendrocytes and myelin? What are the recommended amounts?
-Aerobic exercise
-20-40 min. 3X a week at 70-80% of training heart rate (THR)
What occurs during Alzheimer’s disease?
-Microglia cause abnormal increases in neuro inflammation, which leads to the release of cytokines and free radicals
-The neuro inflammation leads to β-amyloid plaques
-The good type of microglia helps to reduce the inflammation
What are the two different types of microglia and what are their functions?
-M1 microglia induces inflammation and is the “bad” microglia that attacks the myelin in MS and causes inflammation in Alzheimer’s
-M2 microglia is the non-inflammatory, “good” microglia that helps to regenerate myelin
How many layers is the motor cortex split into?
The motor cortex is split into 6 layers/lamina
What are Betz cells and where do they originate from?
-A type of pyramidal neuron that connects the axon and descend the spinal cord via the corticospinal tract, which synapses directly with the anterior horn cells
-Over 50% of the Betz cells originate in the primary motor cortex
What is the pathway for motor impulses?
-Primary motor cortex
-Through the brain
-To the brainstem
-Midbrain
-Pons
-Medulla
-Through the spinal cord
What are the two corticospinal tracts? Where do they cross?
-Lateral corticospinal tract
-Crosses at cervicomedullary junction
-Anterior corticospinal tract
-Stays unilaterally and crosses over at spinal cord level to innervate bilateral sides
What is the anterior corticospinal tract? What motor tracts does it contain? What muscles does it innervate?
-One long axon from the precentral gyrus to medial motor nuclei
-Contains motor tracts for cevical and upper thoracic cord (trunk)
-Primarily innervates bilateral axial and shoulder girdle muscles
What is an upper motor neuron?
One long axon from the primary motor cortex to the anterior horn cell (CNS)
What are upper motor neuron lesions?
Trauma, diseases, or infections occurring in an upper motor neuron that is in the brain or spinal cord
What are lower motor neurons?
They involve the anterior horn cell and the peripheral nerves
What are lower motor neuron lesions?
Injuries, diseases, or infections associated with the lower motor neurons
Do all neurons in the lateral corticospinal tract travel contralaterally?
No, 10% of neurons in the lateral CST travel ipsilaterally and terminate in the ipsilateral spinal cord
What is the order that the motor system is activated in?
-Posterior sensory cortex sends goals
-Prefrontal cortex plans
-Premotor cortex sequences
-Motor cortex executes the actions
What are the 5 steps of voluntary motor activation?
- Decision made in the frontal lobe
- Motor planning areas and command centers activate (Pre-motor and vision)
- Motor tract delivers signals to alpha motor neurons
- AMNs transmit signals directly to skeletal muscles
- Correction/feedback of motor activity in cerebellum and the sensory cortex, regulating the activity in descending motor tracts
What are the methods of nervous system muscle activation?
-Motor neuron pools
-Systematic method of increasing activation: Henneman’s Size Principle
-Increase the rate of stimulation
What is a motor neuron pool?
-Groups of muscles that cluster into discrete neurons (AHCs) with a common target
-Link across several spinal nerves
-Receive sensory feedback (proprioceptive) from muscle spindles
-Coordinate with patterns of muscles by segments, sensory and cortical input
-The more motor pools recruited, the more strength there will be
What is Henneman’s Size Principle?
Arrangement of motor unit activation
-Smallest motor units activated first
-Medium motor units activated second
-Largest motor units activated last
-Motor units receive common neural input and are recruited according to their sizes
What are the three types of alpha motor neurons? What is their relative excitabilities?
-S type (slow): small and highly excitable
-FR type (fatigue resistant): big and average excitability
-FF type (fatiguable): biggest and low excitability
What is the neural activation size principle?
-Type I motor units have a low activation threshold with lower force production
-Type II motor units have a high activation threshold but have high force production
What does the corpus callosum do?
It connects the 2 hemispheres of the brain and allows them to communicate
What are gyri?
The ridges of the brain that contain cell bodies of the neurons, dendrites, and synapses
What are sulci?
The grooves of the brain, the deeper the grooves, the more cortical brain depth
What is the thalamus?
The “relay center” of the brain, it sends info to the rest of the brain from the body
What does the premotor cortex do?
It arranges activation patterns of our movements/plans our movements
What does the parietal association cortex do?
It is the setup for sensory
Does the sensory or motor cortex have more plasticity?
Sensory cortex
What is the somatosensory cortex responsible for? Where is it located?
-Responsible for receiving and processing sensory information from across the body, such as touch, temperature, and pain
-Located posterior to the Central Sulcus
What is the parietal lobe vital for?
-Vital for sensory perception and integration, including the management of taste, hearing, sight, touch, and smell
-It houses the brains primary somatosensory cortex
What structure in the brain has dopaminergic neurons?
Substantia nigra
What happens when someone loses their sense of smell?
It affects their memory, since memory is associated with smells
What are the purpose of the ventricles?
To make and circulate cerebrospinal fluid
Where does CSF travel through?
CSF travels through the ventricles, spinal cord, central canal, and subarachnoid space
Where is CSF released into?
It is released into the venous blood in the arachnoid granulations in the superior sagittal sinus at the top of the falx cerebri
Where can blood potentially leak into in the brain?
Into the CSF
What is hydrocephaly? When does it most commonly happen?
-Too much CSF in the brain which causes swelling and puts pressure on the brain
-It most commonly occurs in babies and TBI patients
What are arachnoid granulations?
Out-pouchings of the arachnoid membrane into the dural venous sinuses
Where is CSF produced?
In the choroid plexus in the 3rd, 4th, and lateral ventricles
What is the composition of CSF?
The composition is similar to plasma, but low in protein and gets produced at a steady rate
What is the order of CSF circulation?
-Originates in the choroid plexus
-Lateral ventricles
-Foramen of Monroe to III ventricle
-Through cerebral aqueduct
-To IV ventricle
-Through Foramina of Luschka (lateral) and Magendie (medial)
-To subarachnoid space
-Through arachnoid granulations to the dural venous sinus
When do skull fractures occur?
In concussions and traumatic head injuries
What is the foramen magnum?
The foramen where the spinal cord travels through
Does the brain have sensation?
No, but dura mater does
What is dura mater?
-Layer of connective tissue that separates and surrounds the two hemispheres of the brain
-Provides autoimmunity to the brain
What are meninges?
-Layers of protection for the brain
-Dura mater (outer most layer)
-Arachnoid mater (middle layer)
-Pia mater (inner most layer)
What happens if there is a tear to the dura mater?
It is extremely painful
Where do headaches usually originate from?
-Dura
-Blood vessels
-Muscles
What happens if there is a bleed in the subarachnoid space? What are the symptoms?
-A bleed in the subarachnoid space is deadly
-Someone might describe it as the worst headache of their life
-If this is the case call 911 IMMEDIATELY
What is the falx cerebri? What is its purpose?
-Part of the dura mater
-It separates the two hemispheres of the brain
-It helps to protect the brain and keep viruses from spreading from one hemisphere of the brain to the other
What is the tentorium cerebelli?
-Part of the dura mater
-“Tent”
-It separates the cerebellum from the rest of the brain to protect against infections or viruses from spreading to it
What do the primary motor cortex and premotor cortex have in common?
Both project directly to the spinal cord and are capable of some direct control of movement
What is the purpose of the supplementary motor area (SMA)?
-Internally generates plan of movement
-Planning of sequences of movement
-Coordination of the two sides of the body such as bi-manual coordination
Where does the lateral corticospinal tract decussate?
At the cervico-medullary junction in the lower medulla
Where does the anterior corticospinal tract decussate?
At the spinal cord level
Where does the anterior corticospinal tract end? Why does it end there?
-It ends at the mid thoracic area
-Because it primarily innervates the bilateral axial and shoulder girdle muscles
What is the purpose of somatosensation and proprioception?
-Explore
-Identify
-Increase feedback
-Prevent injury
What sensory information comes from the cutaneous layer?
-Tactile
-Superficial (touch)
-Vibration/proprioception/
kinesthesia
-Pain
-Nerve
-Skin
-Visceral
-Muscle, tendons, ligaments, CT
-Temperature
What sensory information comes from the muscle, connective tissue, and joints?
-Stretching
-Static and dynamic force
-Skin
What is proprioception?
Awareness of static joint position
What is kinesthesia?
Awareness of dynamic joint positions
What does sensory information promote?
-Adaptations in posture and movement
-Sent from peripheral nerves
What is sensory perception? How does it help us?
-Awareness of stimuli
-It interprets sensory info into meaningful forms
-It is an active and ongoing process and involves acting within the environment
What are the categories of cutaneous sensory receptors?
-Mechanoreceptors
-Pressure
-Discriminative touch
-Vibration
-Proprioception
-Thermoreceptors
-Nociceptors
What tissues/parts of the body have specialized receptors?
-Vessels
-Connective tissue
-Ligaments
-Tendons
-Viscera
What is a Meissner corpuscle?
-Found in fingertips mostly
-Discriminative touch
-Low frequency vibrations
-Velocity sensitive (2-40mm/s)
-Small receptive field (2-4mm)
How do children learn discriminative touch?
They learn over time by playing w/ different objects
What is a Pacinian corpuscle?
-High frequency vibration
-Sudden stimuli
-Mostly in fingertips
-Deep pressure over large surface
-Large receptive fields (>4mm)
What are Ruffini’s corpuscles?
-Skin stretch direction & force
-Subcutaneous skin
-Large receptive fields (>4mm)
What are Merkel’s disks?
-Surface pressure
-Static touch
-Touch & form (shapes & edges)
-Mostly in fingertips
-Dermis & hair follicles
-Small receptive fields (2-4mm)
What are free nerve endings?
-Unmyelinated
-Pain
-Heat
-Cold
Is a slow or rapid stimulus required to stimulate Meissner’s corpuscles?
Fast
Is a slow or rapid stimulus required to stimulate Pacinian corpuscles?
Fast
Is a slow or rapid stimulus required to stimulate Merkel cells?
Slow
Is a slow or rapid stimulus required to stimulate Ruffini endings?
Slow
Where are free nerve endings found?
-Throughout the skin and viscera
-Epidermis
What happens to free nerve endings after they are damaged? What can this cause?
-Free nerve endings can grow back and grow larger
-This can cause an abnormal increase in pain response
How do pain stimuli translate? What types of stimuli can stimulate free nerve endings?
-They translate potentially damaging stimuli into electrochemical signals
-Mechanical, thermal, or chemical
What are the two different types of pain?
-Nociceptive: activation of pain receptors
-Neuropathic: direct injury to neural tissue
What are symptoms of neuropathic pain?
-Burning sensation
-Radiating pain following peripheral nerve
What are Delta fibers?
-Myelinated free nerve endings
-Carry sharp, stabbing, and pricking pain, or cold
-High threshold
-Immediate pain
What are C fibers?
-Unmyelinated free nerve endings
-Carry dull, achey pains
-Higher activation threshold than delta fibers
-Polymodal pain receptors (Chemical, heat, mechanical, hypoxia)
What is the sizes of axons of different nerve types from smallest to largest? How fast does each travel?
-C fibers
-Delta fibers
-Beta fibers (corpuscles)
-Alpha motor neurons
-Axon and speed of transmission have a direct relationship, so the larger the axon, the faster the transmission
What is the rate of adaptation of free nerve endings?
Slow
What is the rate of adaptation of Meissner’s corpuscles
Fast
What is the rate of adaptation of Pacinian corpuscles?
Fast
What is the rate of adaptation of Merkel’s disks?
Slow
What is the rate of adaptation of Ruffini’s corpuscles?
Slow
What is the muscle spindle (MS)?
-Sensory proprioceptor in the muscle belly
-Intrafusal muscle fibers (muscle spindle) connects w/ extrafusal muscle fibers
-Efferent info is sent from MS to muscle
What sensory receptors are found in the joints?
-Ruffini’s
-Pacinian
-Free nerve endings
How does the muscle spindle work and communicate?
-Transmits information of the length of the muscles as well as the speed of the muscle contraction
-Sends info to the cerebellum
-Unconscious sensation
-Plays a vital role in regulating the contraction of muscle
How does the cerebellum help us with coordination?
-It estimates joint position and force needed to complete movements or tasks
-The muscle spindle sends info to it, and if we estimated our movements incorrectly, the cerebellum corrects it
-It houses motor memory
What type of afferent neuron is the muscle spindle?
Type Ia afferent neuron to CNS
What reflexes test the integrity of the muscle spindle and why?
-Deep tendon reflexes
-Because it causes a quick stretch which makes the muscle contract quickly, which the muscle spindle detects
What root does sensory information go into?
-Dorsal root ganglion
How does the muscle spindle aid in reciprocal inhibition?
-The muscle spindle synapses onto two motor neurons
-One synapses directly onto the motor neuron of the agonist muscle
-The other synapses onto an inhibitory interneuron, then the interneuron synapses onto the motor neuron of the antagonist muscle to force it to relax
What are the two major sensory pathways?
-Anterolateral pathway
-Spinothalamic tract
-Dorsal columns (medial leminiscal pathway)
What sensory information goes through the anterolateral pathway?
-Pain
-Temperature
-Crude touch
Where does the anterolateral pathway decussate?
Spinal cord
What sensory information goes through the medial leminiscal pathway?
-Vibration
-Joint position
-Fine touch
Where does the medial leminiscal pathway decussate?
Medulla
What are the functions of the thalamus?
-Sensory relay center
-Sensory integration
-Influences voluntary movements (BG, cerebellum)
-Influences limbic system & memory
-Vision: visual grasp
-Recognition of pain & temperature
What does non-noxious mechanical stimuli activate?
Beta fibers
What does noxious mechanical stimuli activate?
Delta fibers
What does noxious heat and chemical stimuli activate?
C fibers
What is the Golgi Tendon Organ (GTO)?
-Encapsulated receptor located at musculoskeletal junction
-In series w/ extrafusal muscle fibers
-3-50 GTO per muscle fiber
-Innervated by afferent fiber branches, Ib, by which the distal parts of the tendon-spindle are inneravted
-Detects tension in the tendon
How does the GTO work?
-Detects small change in muscle force (<1g of force)
-Compensates for fatigue in motor units
-Can shut things down to avoid injury by inhibiting muscle contraction
-Reflex regulation of alpha motor neuron
-Context/task dependent because it helps us estimate how much force we need to perform a task
What are gamma motor neurons?
Type II motor neurons that reset the muscle spindle after activation
What does an Upper Motor Neuron UMN) syndrome involve?
-Motor cortex and pathways
-Brainstem
-Cerebellum
-And/or involves the spinal cord and its coordination
Where does an UMN injury reside?
-Injury resides in several areas of the brain and spinal cord
-Major areas are located in the motor cortex or brainstem
-Also involved motor pathways from the major brain areas and the spinal cord involving motor output
Where does and LMN injury reside?
-Anterior horn cell
-Peripheral nerve
What causes UMN syndrome?
The result of the disruption of central motor pathways that arise from the cerebral cortex and pathways in spinal cord
What are the main motor tracts?
-Corticospinal tracts
-Corticobulbar tracts
What are signs of UMN lesions in the brain & brainstem?
-Spasticity
-Weakness, loss of selective control (pathologic synergies) which can lead to contractures
-Hyperactivity; increase in deep tendon reflexes, clonus, and rigidity
-Loss of upright control
What area of the brain is associated with decreased muscular control in UMN syndrome?
Cerebellum
What is clonus?
Repeated rhythmic contractions of individual muscle groups
What is tone? What is it independent of/exclude?
-Resistance to passive stretch as a patient is attempting to maintain a relaxed state of muscle activity
-Independent of joint, skeletal, or ligamentous abnormalities
What does tone reflect?
-Muscle state (relaxation)
-Independent of strength, coordination, or involuntary movement
What is the range of muscle tone from least to greatest?
-Flaccidity (LMN)
-Hypotonia
-Normal
-Hypertonia (UMN)
-Rigidity
What is hypertonia?
-Increase in passive muscle tightness
-Abnormally increased resistance to an external force about a joint
What are the three classifications/subcategories of hypertonia?
-Spasticity
-Rigidity
-Dystonia
What is spasticity?
-Velocity dependent increase in tonic stretch reflexes w/ exaggerated tendon jerks, resulting from the hyper excitability of the stretch reflex
-At multiple joints
What is rigidity?
-Significant increase in resistance to multidirectional external force about a joint
-Usually seen in end stage Parkinson’s Disease
What is dystonia?
-A state of abnormal muscle tone resulting in muscular spasm and abnormal posture, typically due to neurological disease or a side effect of drug therapy
-Usually associated w/ basal ganglia & Huntington’s disease
What are common upper limb postures or synergies that are seen in UMN syndrome?
-Flexed elbow
-Bent wrist
-Pronated forearm
-Clenched fist
-Thumb in palm
What is a common synergy pattern for people that have had strokes?
-Upper extremity flexion synergy
-Lower extremity extension synergy
What is movement ataxia? What area of the brain is it associated with?
-Loss of coordination, tremors, overshooting, loss of velocity
-Associated with cerebellum
What is bradykinesia? What part of the brain is it associated with?
-Slowness of movement
-Associated with the basal ganglia and Parkinson’s disease
What is the grading system for reflexes?
-4 Absent
-3 Just elicit able
-2 Low response
-1 Moderately low
0 Normal
+1 Brisk
+2 Very brisk
+3 Exhaustible clonus
+4 Continuous clonus
What are associated movements?
-Moving one part of the body and another limb moves involuntarily
-Loss of complete selective control
What is an advanced brain lesion?
-Severe injury in the brain (usually from stroke)
-Causes severe motor disruption “posturing”
-All limbs are “fixed” on a posture w/ limited limb movements
-Associated w/ rigidity (severe increase in tone)
-Flexion and extension synergies
What are signs and symptoms of a cerebrovascular accident/stroke?
-Initially flacid
-Later develops spasticity
-Reflexes hyperactive
-Synergistic movements
-Clonus
-Sensory loss
-Cranial nerve changes (facial weakness and vision changes)
-Bladder changes
What is a John Doe spinal cord injury?
-When a whole vertebrae shatters
-The broken pieces irritate the spinal cord
-It doesn’t typically sever the spinal cord
-Mostly from high speed accidents
What are different types of incomplete spinal cord injuries?
-Central cord
-Brown Sequard
-Anterior cord
What is Brown Sequard syndrome?
-Lesion on hemisection of spinal cord
-Ipsilateral UMN signs below the level of lesion
-Ipsilateral loss of tactile, vibration, proprioception loss 1-2 levels below lesion
-Contralateral pain and temp. loss below lesion
-Ipsilateral loss of all sensation
-Ipsilateral LMN signs
What is a transverse cord lesion?
A complete spinal cord injury, which effects all motor & sensation under the level of injury
What is lost on the involved side in spinal cord injuries?
Vibration & proprioception
What is lost on the uninvolved side in spinal cord injuries?
Loss of pain & temp.
What are signs of lower motor neuron lesions?
-Loss of muscle function (weakness/flaccid)
-Loss of sensation
-Tone: hyporeflexia
What are other LMN lesion signs?
-Fibrillations (muscular twitching)
-Fasciculations (worm-like contraction)
-Hypotonia/atonia
Where should you test when examining LMN lesions? Why?
-Test above, parallel, & other side of where the lesion is
-Because some peripheral nerve disease spread, like Guillan Barre
What is neuropraxia? Can the nerve heal from it?
-Loss of myelin
-Leads to weakness
-Typically occurs in M.S.
-Can heal
What is axontmesis? What is another name for it? Can it heal?
-Loss of axon and myelin
-Also called Wallerian degeneration
-Causes atrophy and sensory loss
-Can heal, but it is hard
What is neurotmesis? Can it heal? What syndrome can it cause?
-Complete transection of nerve
-Recovery more difficult due to neuroma formation
-Usually does not heal
-Can cause phantom limb syndrome in patients with amputations
What are nerve root injuries? How do they occur?
-An injury to the nerve right at the nerve root (when it exits the spinal cord)
-Common causes are foraminal stenosis and herniated discs
What is Carpel Tunnel Syndrome? What is the clinical presentation?
-Injury to the median nerve
-Atrophied thenar eminence
-Weakness or paralysis
-Pain along nerve
-Numbness along nerve
-Sensory loss
-Loss of ROM
What are the muscles involved in carpel tunnel syndrome?
-Flexor pollicis brevis
-Opponens pollicis
-Abductor pollicis brevis
What muscle testing should be done for a peripheral nerve injury?
-Test muscles on uninvolved side
-Test muscles on involved side
-Test muscles of adjacent peripheral nerves
What sensory testing should be done for a peripheral nerve injury?
-Ask about pain
-Test sensation to uninvolved side first, then involved side
-Test sensation in the involved sensory distribution
-Test sensation of adjacent peripheral nerves
What are signs and symptoms of injury to the deep fibular nerve/common fibular nerve?
-Numbness and tingling
-Shooting pain along the nerve
-Pain w/ nerve tapping
-Pain at rest
-Hyperreflexia
-Muscular weakness
-Sensory loss in common fibular distribution
What muscles are involved in common fibular nerve injury?
-Fibularis longus & brevis
-Tibialis anterior, EHL, EDL
What are signs and symptoms of a C6 nerve root injury?
-Sensory loss following the C6 dermatome
-Hyporeflexia
-Decreased DTR
-Weakness
-Pain
-Tingling and numbness following C6 distribution
What are the muscles involved in the C6 nerve root injury?
-Biceps
-Brachioradialis
-Wrist extensors
What is diabetic neuropathy?
-Length dependent (distal)
-Blood vessels in distal extremities deteriorate which cuts off the blood supply to the nerves
-Follows a glove and stocking presentation
-Polyneuropathy (many nerves involved)
What structures make up the basal ganglia?
-Caudate
-Putamen
-Globus pallidus
-Subthalamic nucleus
-Substantia nigra
What is the basal ganglia?
-The basal ganglia is a collection of gray matter nuclei
-Contains a variety of complex excitatory and inhibitory connections, utilizing different neurotransmitters
How is the basal ganglia involved in motor control?
-Eye movement (helps us plan where to look)
-Associative function
-Limbic system
How are the caudate and putamen separated?
-Separated by penetrating fibers of the internal capsule but remain joined by cellular bridges
What are the functions of the basal ganglia?
-Initiates and integrates behavior and movement
-Removes unwanted and inappropriate movement
-Plans motor activity
-Regulates motor habits
-“Rewards and motivation”
-Associations with attention
What influences the basal ganglia and how does it influence other structures?
-The cerebral cortex directly influences the basal ganglia
-The basal ganglia influences the cortex via the thalamus
-It also influences the motor system through spinal cord pathways
What is the basal ganglia circuitry to the brainstem?
-Reticulospinal tract
-Vestibulospinal tract
Where do skilled movements arise from in the motor cortex?
-Corticospinal tracts
-Brainstem
How do we select/initiate motor programs?
-Basal ganglia to brainstem
-Basal ganglia to thalamus
What motor pathways come from the spinal cord?
-Central pattern generation
-Muscle movement
-Reflexes
How is the basal ganglia intimately connected to the cortex?
Through parallel loops
What are the parallel loops subdivided into?
-Motor
-Associative (cognition)
-Limbic
What can dysfunction of the basal ganglia and its connectivity lead to?
-Movement disorders (dyskinesias)
-Akinesia
-Bradykinesia
-Hyperkinesia
What are non-motor loop pathologies of the basal ganglia?
-Emotional, cognitive, and psychiatric deficits
-OCD
-Tourette’s
-ADHD
What does functional data suggest about the basal ganglia?
-It is involved in both the preparation and execution of movements, motor control, and learning of motor sequences and habit (implicit learning aka learning yourself)
How is the basal ganglia related to turning?
-It helps us decide where and when to turn based on perceptual decisions
-BG dysfunction creates gait deficits and can make turning hard for people w/ Parkinson’s
How does the basal ganglia help us turn?
-Planning of cervical and trunk rotation
-Changes the angles of hip rotation, while anticipating any environmental disruptions
What are the two motor loops?
-Body movement loop
-Oculomotor loop
What are the two non-motor loops?
-Prefrontal loop
-Limbic loop
Is the direct pathway of the basal ganglia more inhibitive or excitable?
More inhibitive
Is the indirect pathway of the basal ganglia more inhibitive or excitable?
More excitable
What does dysfunctions in the direct pathway of the basal ganglia lead to?
-Hypokinesia
-Under-stimulation (more inhibition of motor cortex)
-Loss of automatic movements
-PD
-Rigidity
-Bradykinesia
What does dysfunctions in the indirect pathway of the basal ganglia lead to?
-Over-stimulation (less inhibition of cortex)
-Hyperkinetic
-Chorea
-Huntington’s
What is the ranking of basal ganglia movement disorders by movement speed (slowest to fastest)?
-Bradykinesia, hypokinesia
-Rigidity
-Dystonia
-Athetosis
-Chorea
-Ballismus
-Tics
-Myoclonus
-Tremor
What is ballistic movements?
-Flinging with large amplitude
-Hemiballismus: unilateral flinging contralateral to lesion
What is a common cause of ballistic movements?
Infarct of the subthalamic nucleus
What are tics?
-Involuntary small jerks or yelling
-Tourette’s syndrome
-4 times more in girls
-Increased in ADHD
-Symptoms come and go
What are tremors?
-Both agonist and antagonist involved
-Bidirectional movement
-Asymmetrical
-“Pin rolling”
-Resting tremor and intention tremor
-Resting tremor is commonly seen in Parkinson’s
What is lead pipe rigidity?
-Continous throughout whole movement
-Agonist and antagonist involved
What is cogwheel rigidity?
-Ratchet like interruptions as the limb is passively moved
-Normal stretch reflexes
-Shoulders and cervical spine first affected
-Prolonged results in contracture
What is Parkinson’s disease? What are the signs and symptoms?
-Loss of dopaminergic neurons & production in the substantia nigra
-Festinating gait (slow & shuffling, difficult to initiate)
-Difficulty turning corners
-Stooped forward & kyphotic
-Gait impediments coincide with visual, decision making, and motor control deficits
-Freeze with impediments/objects in path
-Resting tremors
-“Reptillian stare”/no expression
What symptoms in Parkinson’s disease can present themselves 5 years before the onset of motor symptoms?
-Sleep issues/insomnia
-GI issues
Where does gait originate from?
-Brainstem and descends to spinal cord
-Descending pathways come from mesencephalic locomotor region and lateral hypothalamus
-The MLR project into neurons in the pons and medulla , then project into the spinal cord to activate the CPGs involved in locomotion
How does the Mesencephalic Locomotor Region (MLR) and lateral hypothalamus help in gait?
It helps us plan and initiate walking
What is the Mesencephalic locomotor region (MLR)?
Area of the brainstem that is implicated in the control of gait and balance
What is the pedunculopontine nucelus (PPN)? How is it related to Parkinson’s disease?
-Located in the MLR
-Plays a crucial role in appearance of axial symptoms in PD
-Dysfunction of cholinergic neurons in the PPN is what causes the symptoms in PD
How does deep brain stimulation help PD patients?
Because it activates the MLR and PPN, which helps to alleviate locomotor symptoms
What is labile presentation? What patient population is it commonly seen in?
-Awake, but not engaged
-Seen in PD
What other additional basal ganglia diseases are there?
-Brain anoxia (cerebral palsy, common in babies before 1970)
-Huntington’s disease
-Stroke
How is movement carried out?
-Preplanning: prefrontal cortex
-Preparation: premotor cortex
-Initiation, selection, memory, emotion: basal ganglia
-Activation: primary motor cortex
How much oxygen is used for brain function?
20% at all times
Where do 80% of strokes occur?
Middle cerebral artery
What is a Stem stroke?
A stroke that occurs in the common cerebral artery, which causes a massive stroke
What separates the frontal and parietal lobe?
The central sulcus
What does the frontal lobe house?
-Premotor cortex
-Primary motor cortex
-Supplementary motor area
What does the parietal lobe house?
-Primary somatosensory cortex
-Parietal association cortex
-Secondary somatosensory area
What is decerebrate posturing?
Abnormal extension posturing and rigidity
What is decorticate posturing?
-Abnormal UE flexion rigidity
-Abnormal LE extension rigidity
