Chapter 11 - Nervous System Flashcards
Meninges and Layers of Meninges
membranes that protect brain and spinal cord due to lying between bone and soft tissues of the nervous system
Layers of Meninges:
○ Epidural space
- Dura mater: tough dense connective tissue
○ subdural
- Arachnoid: middle web like layer
○ Subarachnoid space containing cerebrospinal fluid
- Pia mater: attached to the surface of brain, spinal cord and contains blood vessels and nerves to nourish the CNS
Cerebrospinal Fluid(CSF) and Ventricles
- CSF is produced in the 4 ventricles circulated through the brain and spinal cord
- It is constantly being made and drained
- Helps protect and brings nutrients to the CNS neurons
- Maintains stable ionic concentrations
- 2 lateral, 3rd ventricle and 4th ventricle
CSF pressure:
interference with continuous secretion and circulation of CSF can increase intracranial pressure which can lead to collapse of cerebral blood vessels or injury of the brain tissue
- Pressure can be relieved by insertions of a drain into the subarachnoid space
Traumatic Brain Injury(TBI) and the 3 types
a result of mechanical force(fall, attack, incident
- Concussion: mild TBI resulting from a onetime injury with no lasting symptoms
- Chronic Traumatic Encephalopathy: sports related, mild repetitive TBI from small injuries over time which lead to symptoms beginning years later
- Blast related brain injury: sever TBI resulting from explosions in combat situations leading to cognitive decline years after injury
4 Portions of Brain
○ Cerebrum(2 hemispheres connected by corpus callosum)
○ Cerebellum
○ Diencephalon (thalamus and hypothalamus)
○ Brainstem (midbrain, pons, medulla oblongata)
Features of Cerebrum
§ Gyri: ridges
§ Sulci: grooves
§ Fissures: longitudinal and transverse
§ Grey matter contains neuron cell bodies which are unmyelinated
§ White matter is composed of myelinated axons connecting to the cell bodies in the grey matter
Sensory Areas of Cortex and their location
Speech:
- Wernicke’s area(posterior superior temporal lobe)
Cutaneous sensory area: interpretation of skin sensations
- Parietal lobe
Visual area:
- Occipital lobe
Auditory area:
- Temporal lobe
Taste:
- Base of insula
Association Areas of the Cortex
regions not primarily motor or sensory but connect to each other and other structures in the brain
- Frontal lobe: concentrating, planning, problem solving - Parietal Lobe: understanding speech and choosing words - Temporal Lobe: interpreting sensory experiences(speech, reading) storing memories - Occipital Lobe: analyzing and combining visual images Insula: translating sensory information into emotional responses
Motor Areas of the Cortex(3)
Primary Motor Cortex: Frontal lobes controls voluntary muscles
- Crossing over of axons occur
Broca’s area: in the inferior frontal lobe and controls muscles needed for speech
Frontal Eye Field: superior frontal lobe controls voluntary movement of eyes and eyelids
Hemisphere Dominance
we all have one hemisphere which is dominant and often it’s the left hemisphere for people(right handed)
- Dominant controls language skills in speech, writing, reading, verbal, analytical skills
- Non dominant controls nonverbal tasks, motor orientation in space, interpreting musical and visual patterns, emotional responses
Long Term Potentiation
increase in neurotransmitter release and effectiveness on post synaptic transmission upon repeated stimulation
Basal Nuclei
the basal ganglia which is a cluster of neuron bodies in the PNS that produce dopamine and control voluntary movement
Parkinsons Disease
degeneration of neurons in the substantia nigra, resulting in less production of dopamine
- Creates symptoms such as tremors, rigidity, small handwriting, speech difficulties
- No treatments only meds to treat the symptoms
Diancephalon
between the cerebral hemisphere and above the brainstem
- Thalamus: gateway for sensory impulses and channels impulses to appriopriate part of cerebral cortex for interpretation - Hypothalamus: maintains homeostasis by linking nervous and endocrine systems
Limbic System
several structures in the brain which controls emotional responses, feelings, behavior oriented toward survival
4 F’s in Limbic System
- Fighting
- Feeding
- Feeling
- Reproduction
Brainstem
lowest part of the brain functionally and location wise which connects brain to the spinal cord
- Midbrain
- pons
- reticular formation
Midbrain
contains bundles of fibers that join lower parts of brainstem
- Cerebral aqueduct: connects 3&4th ventricle
- Cerebral peduncles: main motor pathway
- Corpora quadrigemina: centers for visual and auditory reflexes
Red nucleus: role in postural reflexes
Pons
relays nerve impulses between medulla oblongata and cerebrum and helps regulate rhythm of breathing
Medulla Oblongata
conducts impulses between brain and spinal cord and controls cardiac vasomotor and respirator centers
- Injuries to this area is often fatal
Reticular Formation
a complex network of nerve fibers throughout the brainstem which filters incoming sensory information and discarding the unimportant ones
- Decreased activity causes sleep
Sleep
normal, recurring and reversible state of unconsciousness characterized by limited sensory input and inhibited skeletal muscle activity
Types of Sleep:
REM:
- Paradoxical: some areas are highly active
- Dreaming occurs
NREM:
- Person is tired
- No dreams
- Decreased activity of reticular formation
- 3 stages
Cerebellum
integrates sensory information concerning position of body parts, coordinates skeletal muscle activity and maintains posture
- Abror vitae(white matter)
- Cerebella cortex(gray matter)
Brain Waves
recordings of fluctuating electrical changes in the brain
Types of waves:
- Alpha: awake, resting
- Beta: active mental activity, under tension
- Theta: mostly in children, in adults during stress/sleep
- Delta: when your asleep
Amyotrophic Lateral Sclerosis
involves degeneration of motor neurons in spinal cord, brainstem and cerebral cortex leading to speaking difficulties, dragging foot, clumsiness, fatigue, coordination issues and muscle twitches
- Cognitive function remains normal
Spinal Cord Injuries
compression or distortion of the spinal cord resulting in damage or death of neurons
- Injury to ascending leads to loss of sensation
- Injury to descending leads to loss of movement
- Paralysis is from injury to both
Peripheral Nervous System
nerves that connect the CNS to the rest of the body
- 12 pairs of cranial nerves
- 31 pairs of Spinal nerves
Peripheral Nerve Structure
- Endoneurium: surrounds axons
- Perineurium: surrounds bundles of axons in fascicles
- Epineurium: surrounds
- Perineurium: surrounds bundles of axons in fascicles
Cranial Nerves, # and Basic Function
I - Olfactory: sense of smell
II - optic: sense of sight
III - oculomotor: movement and blinking of eyes
IV - trochlear: moving eyes up and down
V - trigemial: nerves to facial muscle and mastication muscles
VI - abducens: nerves to muscles in the eye
VII - facial: nerves to facial muscles
VIII vestibulocochlear: nerves for hearing and equilibrium
IX - Glossopharyngeal: nerves for muscles in swallowing and taste
X - Vagus: nerves for heart, larynth and gastro tract
XI - Accessory: nerves for neck muscles
XII - Hypoglossal: nerves for movement of tongue
Optic Chiasma
the area where optic nerves from the eyes cross over to allow full sight even if one area of the brain is damaged
Functions of the Spinal Cord
- Center for spinal reflexes(withdrawal reflexes, crossed extensor reflex, contraction reflex)
- Conduit for impulses to and from the brain
Spinal Cord
- Begins at the foramen magnum and terminates at the first and second lumbar vertebrae
- Enlargements are areas where nerves go out to the limbs(cervical and lumbar regions)
- Gray matter is on the inside arranged in horns
- White matter is on the outside arranged in funiculus
- Posterior roots contain sensory neurons
- Anterior roots contain motor neurons
Nerve Plexus
complex networks formed by anterior rami of spinal nerves. Various nerves are recombined so they all head to the same peripheral body part
3 Main Plexus
Cervical Plexus: formed from C1-C4 spinal nerves which supply muscles and skin of the neck
Brachial Plexus: branches of C5-T1 which lie deep within the shoulders and supply muscles of arms and forearm
Lumbosacral Plexus: suppies motor impulses and blood to the thighs and legs
Spinal Nerve Injuries
- Whiplash: sudden bending of the neck
- Broken/dislocation of vertebra: results in damaged axons which can paralyze the diaphragm
- Sciatica: compression of intervertebral disc in lumbar region resulting in pain in lower back, gluteal region
- Carpal tunnel syndrome: repeated movements of hand inflame tendons that pass through the carpal tunnel.
Autonomic Nervous System
- Controlled by hypothalamus
Divided into sympathetic and parasympathetic
