neuro assessment Flashcards
HOW DOES THE CNS COMMUNICATE WITH THE PNS? (think neurons)
VIA NEURONS AND NERVE FIBERS
Sensory neurons from the PNS transmits information to the CNS for processing
CNS sends signal via motor neurons back to the PNS to respond
Dendrite
(dend is the receiver)
Dendrite
Receives stimulation in order for the cell to become active
Cell body (Soma) - what does it do?
(soma has the info)
Cell body (Soma)
Processes information
axon
Axon
Conducts and transmits impulses to other neurons or end organ; varies in length from few centimeters up to few feet
Myelin sheath - produced by what in the PNS?
(schwann has PNS)
Myelin sheath
Produced by schwann cells in the PNS
Insulates the axon; allows for faster conduction
Axon terminal
Axon terminal
Releases neurotransmitter
NEUROTRANSMITTERS
Chemicals that are released by the presynaptic cells at the end of the axon
These chemicals bind to the receptors at the post-synaptic dendrites to initiate an electrical impulse
Whether there is depolarization “action potential” depends on the number of presynaptic cells firing (summation) or the frequency with which one cell fires (temporal summation)
Excitatory neurotransmitters - examples
(excite the GHN)
Excitatory neurotransmitters
Norepinephrine, glutamate, histamine
Inhibitory neurotransmitters - ex.
(inhibited by G)
Inhibitory neurotransmitters
Gamma-amino butyric acid ( GABA), glycine
Drugs and toxins can modify or block these neurotransmitters
Both excitatory and inhibitory
(sneeze in the dope for both)
Both
Acetylcholine, Dopamine
FUNCTIONS OF A NEURON - can they regenerate?
Functions:
Initiates (nerve impulse), receives and processes messages from internal and external signals
Neurons are not mitotic: therefore “can not regenerate” themselves if damaged.
Thus, primary tumors of neurons are rare
However recent evidence shows astrocytes play in role in reducing neuroinflammation during damage and may proliferate after certain CNS injuries
Sensory neuron
Sensory neuron
Activated by sensory input from sensory receptor neurons
Interneurons
Interneurons
transmits impulses between nearby motor and sensory neurons (bypasses signal to brain as in reflex arc to prevent injury)
Motor neuron
Motor neuron (Upper and Lower Motor neuron)
Sensory input processed by the cerebral cortex transmits impulses via upper and lower motor neurons to elicit a motor response
UPPER MOTOR NEURON
(up must go down)
Located in the cerebral cortex
Signal travels down Corticospinal tract (descends to spinal cord to control movements below neck)
LOWER MOTOR NEURON - where is it located?
(the lower horn)
Located in anterior horn of the spinal cord
Controls skeletal muscles
Corticobulbar tract (ends at the brain stem; controls mov’t of cranial nerves)
UMN LESION (damage to motor neurons) - what are the symptoms?
(uma is a spaz)
Spasticity
Hypertonia
hyper-reflexia
+Babinski reflex
Muscle atrophy due loss of innervation
LMN LESION
(lame is flaccid)
Flaccidity
Hypotonia
Hypo-reflexia
- Babinski
Muscle atrophy due to disuse
PROTECTING THE NEURONS: GLIAL CELLS (NEUROGLIA)
(glee protects me)
FUNCTION:
Surround neurons, provide support and insulation
Most abundant cells in the brain (comprise ½ the mass of the brain and spinal cord)
Left Hemisphere
Logic and reasoning
Math and Science
Speech, words, and language
Detail oriented
Reality based
Right Hemisphere
Creativity/imagination
Impulse control
Feelings and intuition
Spatial perception
Abstract meaning
ANATOMY OF THE BRAIN
The brain includes:
The cerebrum (left/right cerebral hemispheres) 4 lobes
The cerebellum
The brain stem 3 parts (midbrain, pons, medulla oblongata)
Broca’s area: on TEST - where is it located?
(broc expresses himself in the front)
Located in the frontal lobe (left hemisphere)
Wernicke’s area: where is it located? and what type of language?
(Wernicke is receptive in the temple)
Located in the temporal lobe (left hemisphere)
Enables the processing of words into coherent thought and recognition of the idea behind the written or heard words
Responsible for receptive language
Limbic System: Emotion and Motivation - parts of the limbic system? (FAT CHH - ic)
Amygdala
Hippocampus
Thalamus
Hypothalamus
Cingulate gyrus
Fornix
Basal Ganglia
Group of structures located centrally in cerebrum
Responsible for:
Initiation, execution, and completion of movements
Learning and emotional response
Autonomic movements (blinking, swallowing, swinging of arms)
CEREBELLUM
(belly dancer is fine)
Receives input from the cerebral cortex, spinal cord, sensory and inner ear
Coordinates:
Voluntary movements
Sense of body position
Balance and equilibrium
Speech
Fine movements
BRAIN STEM - on TEST (brain stem is the worst stroke you can have) - parts of the brainstem
(stem is having PMM)
Consists of :
Midbrain
Pons
Medulla oblongata
Grey Matter - composed of what?
(TBD grey)
Mainly composed of cell bodies, dendrites and axon terminals of neurons
White Matter
(myla is white)
Mainly composed of myelinated axons connectingall the neurons in the brain and spine
WHAT IS PROTECTING YOUR BRAIN
Skull – physical barrier
Meninges
Blood Brain Barrier
Cerebral Spinal Fluid
Dura mater
(dura ble skull and arachnoid)
Dura mater – tough membrane between the skull and arachnoid
Arachnoid
(bathethe arachnoid)
Arachnoid bathed in CSF and contains blood supply
Pia mater
(pia is full of fluid)
Pia mater – additional barrier, secretion and containment of CSF
THE BLOOD BRAIN BARRIER (BBB)
Complex of tightly joined endothelial cells of the cerebral capillaries and astrocyte end feet together keep some substances of plasma out of the CSF and brain
CEREBROSPINAL FLUID (CSF) - where is it located?
(school is sub ventricles)
Located in the subarachnoid and *ventricles
FUNCTION OF CSF - 3 things
Buoyance- allows brain to float in the cranium
Protection – cushions the brain from impact
Chemical stability – removes waste and optimizes environment for neurons
CEREBRAL CIRCULATION
Internal carotid artery supplies blood to the cerebrum
Anterior cerebral artery
Middle cerebral artery
Posterior cerebral artery
Vertebral artery
From the subclavian artery join to form the basilar artery to provide blood flow to the cerebellum
CEREBRAL CIRCULATION - Pontine branches
(ponte puts in basil stem)
Pontine branches
Branches from the basilar artery providing blood to brain stem
CEREBRAL CIRCULATION - Circle of Willis - on TEST
(Willis is my collateral)
Circle of Willis
Arterial structures that provides collateral circulation through alternate arteries to prevent brain ischemia
VERTEBRAL COLUMN - what about sacral and coccygeal?
There are 4 curves in the spine:
7 cervical
12 thoracic
5 lumbar
5 fused sacral
4 fused coccygeal
The spinal cord passes through the vertebrae
THE SPINAL CORD - where does it end? and what covers it?
Spinal cord : ends between L1 and L2.
Axons from the lumbar and spine extend downward and exit the intervertebral foramen
Note the meninge layers also cover the spinal cord
PERIPHERAL NERVOUS SYSTEM - comprised of which nerves? (2 types)
PNS: comprises of spinal nerves and cranial nerves
31 pairs of spinal nerves (8 cervical, 12 thoracic, 5 lumbar, 5 sacral and I coccygeal)
NERVE TRACTS - 2 types - you know this
Ascending tracts: nerve fibers that carry sensory stimuli from periphery (e.g. skin, muscle, blood vessels) toward the brain
Descending tracts: nerve fibers that carry impulses responsible for motor movement
Peripheral Nervous System - Dermatomes - innervated by what?
Dermatomes: Area on the skin that is innervated by spinal nerves. Each of these spinal nerves relay sensation from a particular region of skin to the brain
Peripheral Nervous System - Sensory receptors
Sensory receptors: located throughout the body to monitor and transmit sensation of pain, temp, touch, vibration, pressure, visceral sensation and proprioception.