CNS
central nervous system
central nervous system
brain and spinal cord
PNS
peripheral nervous system
peripheral nervous system
* includes the 12 pairs of cranial nerves
* 31 pairs of spinal nerves and their branches
afferent
SENSORY messages INTO the CNS from sensory receptors
efferent
* MOTOR messages OUT FROM the CNS to muscles & glands
* AUTONOMIC messages that govern the internal organs & blood vessels
frontal lobe
* intellectual functions
* personality
* behaviour
* emotion
parietal lobe
postcentral gyrus is the primary center for SENSATION
occipital lobe
primary visual receptor center
temporal lobe
* primary AUDITORY reception center
* behind the ear
* hearing
* taste
* smell
Wernicke's area
* in the temporal lobe
* associated with language comprehension
receptive aphasia
* hear sound but it has no meaning; like a foreign language
* result of damage in temporal lobe of dominant
hemisphere
Broca's area
* in the frontal lobe
* mediates motor speech
expressive aphasia
* unable to talk
* language understood & knows what wants to say but can produce only a garbled sound
* result of injury to frontal lobe of dominant hemisphere
Basal Ganglia
* deep within the two cerebral hemispheres
* control AUTOMATIC associated movements of the body e.g.:
arm swing alternating with leg movement during walking
Thalamus
* main relay station for the nervous system
Hypothalamus
major control center
* anterior & posterior pituitary gland regulator
* coordinator of AUTONOMIC nervous system activity
* temperature
* heart rate
* blood pressure
* sleep center
* emotional status
Cerebellum
* coiled structure located under occipital lobe
* motor coordination & smoothing of voluntary movements
* operates SUBCONSCIOUSLY
* equilibrium (postural balance of body)
* muscle tone
Cerebral Cortex
* cerebrum's outer layer of nerve cell bodies
* grey matter: lacks myelin
* center of HIGHEST functions:
- thought, memory, reasoning, sensation, & VOLUNTARY movement
myelin
* white insulation on nerve cell axon
* increases the conduction velocity of nerve impulses
Cerebrum
* two hemispheres
- left is dominant in ~ 95% of people
* each hemisphere is divided into four lobes:
- frontal
- parietal
- temporal
- occipital
Neurological cell damage
deprived of blood supply:
* occluded cerebral artery
* vascular bleeding
* vasospasm
Brain Stem
central core of brain:
* Midbrain
* Pons
* Medulla
Midbrain
* most anterior part of brain stem
- still has basic tubular structure of spinal cord
* merges into thalamus & hypothalamus
* contains motor neurons & tracts
Pons
* enlarged area of brain stem
* contains ascending & descending fibre tracts
Medulla
contains all ascending & descending fibre tracts connecting the brain & spinal cord:
* vital AUTONOMIC
centers
- respiratory
- cardiac
- gastrointestinal
- nuclei for CV VIII - XII
- pyramidal decussation occurs here
Pyramidal decussation
MOTOR nerve fibres originating in motor cortex, travel to brain stem, CROSS TO OPPOSITE (contralateral) SIDE & then pass down in lateral column of spinal cord
Spinal Cord
* main highway for ascending & descending fiber tracts that connect brain to spinal nerves
* mediates reflexes.
CNS pathways: Crossed
representation
* LEFT cerebral cortex receives sensory information from and CONTROLS motor function to the RIGHT side of the body
* right cerebral cortex interacts with the left side of the body
CNS Sensory Pathways
* Spinothalamic Tract
* Posterior (Dorsal) Columns
Spinothalamic Tract
CNS SENSORY pathway of PAIN/TEMPERATURE/CRUDE TOUCH
> fibers enter dorsal root of spinal cord & synapse w a second sensory neuron
- cross to opposite side
- ascend up spinothalamic tract to thalamus
* Pain/Temperature ascend lateral spinothalamic tract
*C
Posterior (Dorsal) Columns
CNS SENSORY pathway of sensations of PROPRIOCEPTION/VIBRATION/STEREOGNOSIS
> fibers enter dorsal root & ascend up the same side of the spinal cord to the brain stem
- at medulla, synapse with a second sensory neuron and then cross
- travel to thalamus, sy
Proprioception
sensation of POSITION:
without looking, you know where your body parts are in space and in relation to each other
Stereognosis
finely LOCALIZED TOUCH:
without looking, you can identify familiar objects by touch
Crude Touch
light touch NOT precisely LOCALIZED
Pain in Heart Referred to
* chest
* shoulder
* left arm
Organs Absent from Brain
Map
pain originating in these organs is referred to areas they were adjacent to during fetal development
* heart
* liver
* spleen
Pain in Spleen Referred to
top of the left shoulder
Pain in Liver may be
Referred
* right shoulder blade
* dull ache in the upper right portion of the abdomen
* may be accompanied by back pain or abdominal pain.
Corticospinal/Pyramidal Tract
CNS HIGHER, more evolved MOTOR pathway:
* originates in pyramid-shaped cells in MOTOR cortex
* Motor nerve fibres originating in the motor cortex, travel to brain stem, cross to opposite (contralateral) side and then pass down in lateral column of spinal
Homunculus / Somatotropic
Organization
* graphic representation of MOTOR pathways
* brain map that relates space occupied on map to body parts; those whose movements are relatively more important to human body (e.g. the hand) occupy proportionately more space on the brain map
Extrapyramidal Tracts
CNS LOWER more primitive MOTOR system:
* include all motor nerve fibers originating in the
- motor cortex
- basal ganglia
- brain stem
- spinal cord
that are outside the pyramidal (corticospinal) tract.
* maintains muscle tone
* control body movements
- e
Cerebellar System
CNS MOTOR system receives information about the position of muscles and joints and the kind of messages being sent from the cortex to the muscles > integrates this information and uses feedback pathways to control the cortex or down to lower motor neurons
contralateral
opposite
Precentral gyrus
* immediately anterior to the central sulcus
* primary MOTOR area
* also referred to as the "motor strip", contains neurons that project to muscles to execute movement of body parts
- more fine movements, e.g. fingers, controlled by a greater number of ne
Postcentral gyrus
* primary SENSORY area
* immediately posterior to the central sulcus
* receives information primarily from the skin and muscles
UMNs
upper motor neurons:
* located completely within the CNS
- corticospinal tract
- corticobulbar tract
- extrapyramidal tract
upper motor neurons
* located completely within the CNS
* complex of ALL the descending motor fibers that can influence or modify the lower motor neurons
- corticospinal tract
- corticobulbar tract
- extrapyramidal tract
* convey impulses from the motor areas of the cerebral
UMN diseases
* cerebrovascular accident
* cerebral palsy
* multiple sclerosis
LMNs
lower motor neurons:
* located mostly in the peripheral nervous system
* cranial nerves
* spinal nerves
CVA
cerebrovascular accident / stroke
cerebrovascular accident
* also called STROKE
* sudden death of some brain cells due to lack of oxygen when the blood flow to the brain is impaired by blockage or rupture of an artery to the brain
cerebral palsy
* group of non-progressive, non-contagious motor conditions that cause physical disability in human
development, chiefly in the various areas of body movement.
* cerebrum is the affected area of the brain - most likely involves connections between cortex
lower motor neurons
* located mostly in the peripheral nervous system
* cell body is located in the anterior grey column of the spinal cord
* nerve extends from spinal cord to the muscle
* final common pathway; provids final direct contact w muscles
* any movement MUST be tr
Tardive dyskinesia
* form of dyskinesia: difficulty NOT moving
* tardive: having a slow or belated onset
* repetitive, involuntary, purposeless movements:
grimacing/tongue protrusion/lip smacking/puckering/pursing of lips/rapid eye blinking
* rapid movements of the extremit
multiple sclerosis
* name refers to scars (scleroses�better known as plaques or lesions) particularly in the white matter of the brain and spinal cord, which is mainly composed of myelin
* inflammatory disease in which the fatty myelin sheaths around axons of brain & spinal
LMN diseases
* spinal cord lesions
* poliomyelitis
* amyotophic lateral sclerosis
amyotophic lateral sclerosis
* ALS - Lou Gehrig's disease
* form of motor neuron disease
* progressive, fatal, neurodegenerative disease caused by degeneration of motor neurons & nerve cells in CNS that control voluntary muscle movement.
infantile paralysis
poliomyelitis
poliomyelitis
* often called polio or infantile paralysis
* acute viral infectious disease spread from person to person, primarily via the fecal-oral route
* Greek: "grey inflammation"
* ~ 90% of infections cause no symptoms
* affected individuals can exhibit a range o
dyskinesia
disorder resulting in presence of:
* involuntary, repetitive body movement
* diminished voluntary movements
Parkinson's disease
* difficulty moving
* degenerative disorder of CNS that impairs motor skills, cognitive processes, & other functions
* syndrome of tremor, rigidity, bradykinesia & postural instability
* non motor symptoms are autonomic dysfunction, cognitive and neurobeh
bradykinesia
* slow movement
* can occur in Parkinson's disease
* one of the extrapyramidal side effects of antipsychotic medications.
aphasia
* disorder resulting from damage to portions of brain responsible for language
* usually occurs suddenly, often result of stroke or head injury
* may develop slowly, as in case of brain tumor, infection, or dementia
Alpha-receptors
* located on the arteries
* stimulated by epinephrine or norepinephrine
- arteries constrict^ BP^blood flow returning to heart
* blood vessels in skeletal muscles lack alpha-receptors because they need to stay open to utilize the increased blood pumped by
Alpha-blocker medication
* causes vasodilation: arteries dilate
* used to treat hypertension.
Beta receptors
Beta 1 receptors - located in the heart
- when stimulated ^HR & ^ heart's strength of contraction or contractility
Beta 2 receptors - located in bronchioles of lungs & arteries of skeletal muscles
_ when stimulated ^diameter of bronchioles to let more air