Clin Phys 5 Flashcards
The peripheral nervous system detects
a stimulus and relays it to the _____
central nervous system (sensory)
The central nervous system (brain, spinal cord) integrates this information to create a ______
response
The response is carried to ______ (muscles, glands, blood vessels) via the ___________
peripheral nervous system (motor)
which part of the neruon receives a stimulus from a
neuron or a receptor
dendrite
which part of a neuron integrates the stimuli and ranks it (compares it to other stimuli)
Cell body, axon hillock
which part of the neuron passes along another stimulus
if it is adequately stimulated
axon
Axons are carried in bundles as:
Nerves in the _____
Tracts in the ______
Nerves in the peripheral system
Tracts in the central nervous system
Most neuronal cell bodies reside in the
CNS, with a few exceptions:
- Dorsal root ganglia
- Autonomic ganglia
- Enteric ganglia
neuronal cell bodies for the axons that bring most sensory information from the PNS to the CNS
Dorsal root ganglia
help regulate the activities of the autonomic nervous system
Autonomic ganglia
help regulate the activity of the gut
Enteric ganglia
Responsible for most of our “higher functions”.
cerebral cortex
What are the functions of the cerebral cortex?
- formation, storage, retrieval of memory (together with the limbic structures)
- Speech & language
- Abstract thinking, math, planning and executing plans
the cerebral cortex is responsible for….
“What we’re conscious of”
- Perception (i.e. what we consciously sense)
- Voluntary movements, both simple and complex
what lobe: Complex motor plans – anterior portions + precentral gyrus
frontal lobe
what lobe: Motor aspects of speech – anterior and inferior to the precentral gyrus
frontal lobe
Planning, abstract thinking, social behaviour (executive functions) – distributed throughout ______ and _______ lobes
frontal and parietal lobe
what lobe: Perception of touch, temperature, vibration – postcentral gyrus
Parietal Lobe
Perception of “where our limbs are” (proprioception) – postcentral gyrus
Parietal Lobe
Memory, executive functions, abstract reasoning – distributed throughout the ______ lobe
parietal
hearing, scent, taste, recognition of speech and memory describe which lobe?
Temporal Lobe
vision, Areas that relate visual stimuli to “actual things” – i.e. association cortex and Memories related to
what has been seen describes what lobe
Occipital Lobe
Memory formation requires attention and structures that “process” and form new memories. Where is attention found?
prefrontal lobe
Memory formation requires attention and structures that “process” and form new memories. Where are memory “processors” found?
the structures of the limbic lobe below the temporal
lobe
- hippocampus and amygdala
Memory formation requires attention and structures that “process” and form new memories. Where is memory “storage”?
Memories tend to be stored in the cortex
“close to” the sensation they’re associated with
- i.e. – the memory of a voice or word is likely in
or close to the temporal lobe
Structures that lie below the cortex, close to the middle
of the parietal and temporal lobes
the basal ganglia
what does the the basal ganglia serve?
Serve to refine and regulate behaviours or movements
what structure causes movements to be “inhibited” (tics, unnecessary movements, non-speech vocalizations) and also allows or encourages intended movements?
the basil ganglia
The basil ganglia are impaired in several diseases. What happens when this structure loses function?
▪ Tremors, rigidity, difficulty initiating movements
▪ Random, purposeless movements
▪ Tics, vocal utterances
▪ Personality changes
list three structures that lie deep to the basil ganglia
▪ Striatum
▪ Globus pallidus
▪ Subthalamic nuclei
Relays information from sensory receptors in the
PNS to the cortex including Joint/limb position and
movement, pain, touch and movement
Thalamus – major roles
Relays information from brain areas to refine motor planning such as the cerebellum and basal ganglia
Thalamus – major roles
what are the major roles of the hypothalamus?
- Controls much of the endocrine system, along with the pituitary gland
- Regulates temperature, activity of the autonomic nervous system, fluid balance
- Some thalamic nuclei modulate emotion and memory formation
the cerebellum is about ____ of the mass of the brain
10%
- a highly folded and complex strucutre
what is the general function of the cerebellum?
Compares information from the receptors that sense:
* Joint position and movement
* Gravity and equilibrium
Uses this information to adjust movements that are
formulated in the prefrontal cortex
* It very quickly “error-corrects” movements that are
planned by comparing them to data from the receptors
described above
the brainstem is composed of the _______, _______, and _________.
- Composed of the midbrain, pons, and medulla
All of the pathways that bring sensory information into the brain (from the PNS) or send motor information out of the brain (to the PNS) pass through the _________
brainstem
the spinal cord is isolated from the peripheral nervous system and rest of the body by a set of membranes called the
meninges
the spinal cord is bathed in unique extracellular fluid called the
cerebrospinal fluid
Neurons or axons in the spinal cord ______ usually regenerate after they have been damaged
do not
- Regeneration is common after damage to axons in
the PNS
In the spinal cord, ______ components tend to carry sensory information to the brain while ________ components tend to carry motor information
away from the brain to effectors (muscles in particular)
▪ Dorsal components tend to carry sensory information to
the brain
▪ Ventral components tend to carry motor information
away from the brain to effectors (muscles in particular)
Gray matter: Mostly cell bodies mixed with __________ (unmyelinated/myelinated) axons
unmyelinated
which horns of the grey matter are cell bodies of neurons that activate skeletal muscles
ventral horns
which horns of the grey matter are cell bodies of neurons that relay and integrate sensory information
dorsal horns
White matter is divided into columns – these are __________ axons, no cell bodies. What are the three divisions?
myelinated
- dorsal, lateral and ventral
which columns of white matter contribute to proprioception (joint/limb position), vibration sense, fast pain fibres – sensory to brain
Dorsal columns
which columns of white matter contribute to pain, temperature, itch – sensory to pain
Anterior and lateral columns
which columns of white matter contribute to motor information to skeletal muscles
Anterior columns
How does the Corticospinal Tract work?
- Motor plan formed (prefrontal cortex)
- Activation of neurons in the primary motor cortex (prefrontal
lobe) - Axons travel through the brainstem (medullary pyramids) and
cross over to the opposite side - Activation of primary motor neurons in the ventral horn that
stimulate skeletal muscle contraction OR - Activation of motor neurons in the ventral horn that modify
reflexes
Lateral corticospinal tract controls
fine movements of extremities
Anterior corticospinal tract controls
movements of the trunk
It’s estimated that up to ___% of corticospinal output is to “shut down” reflexes that would oppose voluntary movements
90
Cerebellar modification of motor plans:
- cerebellum integrates information from proprioceptors (spinocerebellar tract) and the inner ear (vestibulocerebellar tract)
- Keeps the cerebellum “up-to-date” on the actual position of
the body in general and specific joints
compares this information with information from the
motor “plan” generated by the frontal lobe
relayed through the pons
cerebellum “adjusts” the motor plan by communicating (via the thalamus) with the frontal lobe and refining the movements relayed by the corticospinal tract
Proprioceptors inform the ____, the ______ and ________ in the spinal cord about the actual position of the body
cortex, cerebellum and neurons
Dorsal column-medial lemniscal system:
proprioceptor → dorsal horn → dorsal column → thalamus → post-central gyrus of the parietal lobe
Spinocerebellar system
propriceptor → dorsal horn → dorso-lateral columns → cerebellum
A motor reflex is a fast, involuntary sequence of
muscular movements that:
- do not need higher brain centres
- are simple
- have protective or stabilizing function
- need to be inhibited in order to perform, purposeful, complex movements
a proprioceptor that senses muscle stretch
Muscle spindle
what happens as a muscle is stretched?
- activates the muscle to contract against the stretch by stimulating the motor neuron in the ventral horn
- inhibits the antagonist muscle
Stretch is caused by hitting the tendon with a reflex hammer
what type of reflex helps to maintain posture
stretch
type of reflex: When a tendon is stretched, the antagonist muscle contracts and the agonist relaxes
Thought to help prevent tearing the tendon during excessive force generation
tendon reflex
type of reflex: In response to a painful stimulus, muscles of flexion are activated to withdraw a limb
Withdrawal reflex
type of reflex: In response to an irritating stimulus, the foot plantar flexes (foot flexes “down”) and the toes curl
plantar reflex
type of reflex: These are simple stretch reflexes activated by striking
the tendon with a reflex hammer → contraction of the
agonist muscle
Deep Tendon Reflexes (DTRs)
Examples of Deep Tendon Reflexes
patellar reflex, triceps reflex
Causes of absent DTRs:
- normal variation (some people are really difficult to
get reflexes from) - damage to sensory or motor nerves innervating the
muscle being tested
Causes of excessive DTRs
- loss of inhibition of reflexes from higher brain centres – usually the corticospinal tract (so damage to the corticospinal tract)
Reflexes are easier to interpret as abnormal when they are
___________ – one side greater/less than the other side
asymmetrical
The plantar reflex is developed as we learn to _____. It the corticospinal tract providing specific feedback to
particular segments of the spinal cord (S1)
walk
If the foot dorsiflexes and the toes spread, this indicates that the corticospinal input to the lower
limb is ____. what plantar reflex is usually an abnormal finding
is poor.
Cerebellar tests include: (4)
▪ rapid alternating movements (RAMS)
▪ point-to-point movements (i.e. patient touches his nose then rapidly touches your finger, and repeats)
▪ heel to shin movements
▪ Gait – how coordinated is the patient’s gait?
What to cerebellar tests rely on?
the ability of the cerebellum to evaluate the body’s position and provide feedback to the rest of the motor system
- If the cerebellum has lost function, then these movements are often clumsy, uncoordinated, and slow
what does romberg sign test evaluate?
evaluate the function of the
dorsal columns
Sensory input from proprioceptors to the cerebellum and the parietal cortex – key for joint and limb position sensing
what is the romberg sign test
Patient stands with feet together and closes her eyes
- If the patient loses balance and starts to fall (support the
patient!), indicates that the dorsal columns could be damaged - visual input is no longer available to help the patient
keep her balance
Corticospinal tract damage often results in a pattern of loss of muscle strength – extensors and supinators of the arm are _______ than the pronators or flexors
weaker
what is pronator drift used for? How is it done?
corticospinal tract test
Patient stands with arms outstretched, palms up, hand
open, eyes closed
The arm “drifts” to a more pronated position, the hand
closes, and the arm tends to descend
