Module 2: Nervous System (Part 2) Flashcards
Brain divisions (4)
1) Cerebrum
2) Brainstem
3) Diencephalon
4) Cerebellum
Ventricles (2)
1) Cavities within the brain that are filled with CSF
2) Four ventricles include the two lateral ventricles, third ventricle and fourth ventricle, which drains into the central canal of the spinal cord
Meninges
Three layers of connective tissue membranes that cover and protect CNS organs and enclose CSF
Dura mater
Leathery, double-layered outer meninx
Subdural space
Space below the dura mater and above the arachnoid space
Arachnoid meninx
Loose layer separated from the dura mater by the subdural space
Subarachnoid space (2)
1) Beneath the arachnoid meninx
2) Filled with CSF and contains blood vessels
Pia mater meninx
Thin connective tissue tightly attached to the brain
Cerebrospinal fluid (CSF)
1) Special fluid formed in the walls of the ventricles from blood plasma by permeating through the CHOROID PLEXUS
2) Cushions the brain and spinal cord by providing buoyancy
3) Circulates through the ventricles and into the subarachnoid space, bathing brain in fluid
Blood-brain barrier (3)
1) Diffusion barrier that prevents most particles from entering the CNS tissue, keeping the brain and spinal cord separate from general blood circulation
2) Formed by astrocyte glial cells
3) Creates a stable chemical environment for the nervous system
Cerebrum
1) Foremost part of brain, comprising 83% of brain mass
Cerebral hemispheres (2)
1) Left and right masses of the cerebrum, separated by MEDIAN LONGITUDINAL FISSURE
2) Left cerebral hemisphere controls right side of the body and right cerebral hemisphere controls left side of the body
Cerebral cortex (2)
1) Outer portion of the cerebral hemispheres
2) Highly convoluted and gray in color
Corpus callosum
White nerve fibers that connect cerebral hemispheres so they can communicate with each other
Gyri
Raised ridges of tissue in cerebral cortex
Sulci
Shallow grooves in cerebral cortex that separate gyri
Right and left central sulcus
Central sulci that go from top to bottom of brain
Fissures
Deeper grooves that separate large region of the brain
Transverse fissure
Separates cerebrum from the cerebellum
Four lobes of the brain (4)
Frontal lobe (anterior)
Parietal lobe (posterior top)
Occipital lobe (posterior)
Temporal lobe (sides)
Frontal lobe
Controls higher level executive functions such as reason and decision making
Parietal lobe
Receives sensory information from receptors in the mouth for taste and located in the skin, such as those for touch, pressure and pain
Occipital lobe
Interprets visual input
Temporal lobe
Sensory areas for hearing and smelling
Primary areas of each lobe
Receive or send information for one type of sensory or motor information
Primary motor cortex
Controls voluntary motor movements for all parts of the body
Primary sensory cortex
Parietal lobe receives sensory information from the same parts of the body
Association areas of each lobe (3)
1) Act mainly to integrate more than one type of sensory information for purposeful action
2) Each lobe contains an association area which receives information from the other lobes and integrates it into higher, more complex levels of consciousness
3) Examples include intellect, artistic/creative ability, learning and memory
Broca’s area
Located in the frontal lobe, is responsible for speech PRODUCTION
Wernicke’s area
Located in temporal lobe, is responsible for speech COMPREHENSION
Detailed graph of lobes and primary/association areas
Consciousness and the cerebrum (2)
State of being awake and aware of a person’s surroundings
Cerebrum is portion of brain that governs intelligence reasoning and higher level thinking and can override “lower parts of brain”
Parts of the brainstem (3)
1) Midbrain
2) Pons
3) Medulla oblongata
Medulla oblongata (3)
1) Lies between the spinal cord and pons and is anterior to the cerebellum
2) contains vital centers for regulating heartbeat, breathing and vasoconstriction
3) Contains reflex centers for vomiting, coughing, sneezing, hiccuping and swallowing
Vasoconstriction
Constriction of the blood vessels involved in the regulation of blood pressure
Pons (3)
1) Contains bundles of axons traveling between the cerebellum and the rest of the CNS
2) Works with medulla to regulate the breathing rate
3) Contains reflex centers concerned with head movements in response to visual and auditory stimuli
Midbrain
1) Acts as a relay station for tracts passing between the cerebrum and spinal cord or cerebellum
2) Has reflex centers for higher-level reflexes involving visual, auditory and tactile responses
Superior and inferior colliculi
1) Located on posterior portion of midbrain
2) Control reflexes for the head and neck in response to a sudden visual or auditory stimulus
Diencephalon
Portion of the brain that contains the hypothalamus, thalamus, and epithalamus
Hypothalamus (5)
1) Forms the floor of the third ventricle
2) Responsible for homeostasis of the body environment
3) Contains centers for regulating basic body functions, such as hunger, sleep, thirst, body temp, water balance and blood pressure
4) Controls pituitary gland
5) Link between the nervous and endocrine systems (through neurosecretory cells)
Pituitary gland
Regulates the body hormones of the endocrine system
Thalamus (4)
1) In the roof of the third ventricle
2) Central relay station for sensory impulses traveling upward from other parts of the body and the brain to the cerebrum
3) Receives information, filters out unimportant information, and directs it to appropriate region of the cerebrum
4) Doesn’t receive smell
Epithalamus
1) Forms the roof of the third ventricle
2) Mostly composed of the PINEAL GLAND, which secretes melatonin, which controls the wake-sleep cycle
Cerebellum (6)
1) Located inferiorly and posteriorly to the brain
2) Two hemispheres with deep fissures and three lobes each
3) Often called the “mini brain”
4) OUTER gray matter and INNER white matter, opposite of spinal cord
5) Coordinates body movements by relaying information to the cerebral motor cortex
6) Also involved in maintaining balance, controlling certain eye movements, maintaining normal muscle tone and maintaining posture
Muscle tone (2)
1) The degree at which muscles remain partially contracted while at rest
2) Governed by the cerebellum to keep bones and joints in place
Anterior lobes and posterior lobes of cerebellum
Receive information from the body trunk and influence the motor activities of the trunk, shoulder and pectoral girdle muscles
Vermis (cerebellum) (2)
1) Intermediate portion
2) Coordinates limb movements
Cerebellar peduncles (cerebellum)
Connect cerebellum to other parts of brain
Ataxia (disorder of Cerebellum)
Lack of voluntary muscle motor coordination
Limbic system
1) Just beneath cerebral cortex and contains neural pathways that connect portions of the frontal lobes, temporal lobes, thalamus and hypothalamus
2) Involves portions of conscious and unconscious brain
Cingulate gyrus (limbic system) (2)
1) Located deep to the cerebrum
2) Connects different lobes of the cerebrum
Hippocampus (limbic system) (2)
1) Involved in retrieval and storage of memories
2) Memories not stored in hippocampus itself. Hippocampus acts as a direction center
Amygdala (limbic system)
Smaller portion of limbic system that is involved in emotions such as rage and anger
Fornix (limbic system)
Bundle of nerve fibers that serves as a connection to the hippocamus
Mamillary bodies (limbic system)
Contain fibers that project into the thalamus and assist with the memory of smell
Limbic system and emotions (2)
1) Include rage, pain, pleasure, sorry and rewards/consequences
2) Known as our “feeling brain”
Short term memory (limbic system)
Example - recall 7-digit phone number
Long-term memory (limbic system)
Ability to recall events of the day
Memory
1) Not stored in one area of the brain
2) Hippocampus acts as memory center and assists in storage and retrieval of memories from the cortex
Why are emotionally charged events so vivid in our memories?
Because the limbic system communicates with all sensory areas and accounts for ability of a sensory stimulus to awaken a complex memory
Basal ganglia (also called basal nuclei) (limbic system) (2)
1) Masses of gray matter that lie deep within each hemisphere of the cerebrum
2) Responsible for working with the cerebellum to regulate planning motor movements and motor learning
3) Slows and controls precise movements through inhibition of cerebral cortex
Components of basal ganglia (3)
1) Putamen
2) Caudate nucleus
3) Globus pallidus
Parkinson’s disease
1) Disease of the basal ganglia
2) Apraxia, difficulty with motor planning, is symptom of the disease
3) Apraxia causes rigid movements and difficulty executing a motor plan
Spinal cord (3)
1) 17 inches in length
2) Protected by the surrounding vertebral column
3) Extends from brainstem to first lumbar vertebra
Conus medullaris (spinal cord)
Official termination point of spine at first lumbar vertebra
Cauda equina (spinal cord)
Collection of nerve roots that extends BEYOND the lumbar 1 termination of the spinal cord, which end at the coccyx
Spinal cord protection (3)
1) Vertebral column
2) Meninges: Spinal dura mater, epidural space, arachnoid mater, pia mater
3) CSF
Vertebral column
Column that protects the spinal cord
Spinal dura mater (spinal cord)
Single layer sheath separated from vertebral column by a cushioning fat-filled EPIDURAL SPACE
Filum terminale (spinal cord) (2)
1) Extension of pia mater meninge that runs from the conus medullaris to the coccyx
2) Provides inferior anchor for spinal cord
Spinal tap (2)
1) Removal of CSF for diagnostic testing
2) Done from subarachnoid space inferior to L1
Anterior median fissure and posterior median sulcus (spinal cord)
Two grooves on surface of spinal cord
Anterior groove is much deeper (facing front)
Central canal (spinal cord)
Opening that runs the length of the spinal cord and is filled with CSF
White matter of spinal cord (3)
1) Outer layer
2) Columns: Nerve fibers
3) Tracts:
a) Cross over to the opposite side in spinal cord
b) Ascending
c) Descending
d) Commissural (crossing over)
Dorsal root (2)
1) Incoming sensory neurons (afferent)
2) Dorsal root ganglion: cell bodies of afferent neurons
Ventral root (2)
1) Axons of motor nerves
2) Leaving the spinal cord
Spinal nerve
Location where dorsal root (afferent information) and ventral root (efferent information) come together
Gray matter of the spinal cord
1) Mixture of cell bodies of neurons
2) Organized into horns (attached by commisure)
Gray commisure (spinal cord)
Cross bar that connects the smaller anterior horns
Anterior (ventral) horns (2)
1) Somatic (voluntary) motor neurons
2) Efferent pathways
Posterior (dorsal) horns
Afferent pathway from receptors by way of the dorsal root
Lateral horns (of the gray matter) (3)
1) Located primarily at thoracic level of the spinal cord
2) Contain autonomic sympathetic motor neurons whose axons serve as efferent pathways to visceral organs
3) Exit via the ventral roots of the spinal cord along with those of the somatic motor neurons
Receptors
Receive environmental stimuli and then initiate nerve impulses toward the CNS
Effectors
Muscle fibers and glands which bring about a reaction to the stimulus in the PNS
Cranial nerves (3)
1) Twelve pairs attached to the brain
2) Do not intersect with the spinal cord
3) Connect muscles and organs directly to the brain
Are sensory nerve dendrites long or short?
Are motor nerve axons long or short?
Do mixed nerves have long or short dendrites and axons?
Long
Long
Both long
Special sensory nerves
Carry information responsible for sight, smell, hearing or balance
Olfactory nerve (CN I) (3)
1) Special sensory nerve
2) Sense of smell
3) Only cranial nerves attached to cerebrum, not brainstem
Optic nerve (CN II) (4)
1) Special sensory nerve
2) Sense of sight
3) Retinas of each eye, cross at optic chiasm
4) Synapse in the thalamus to occipital lobe
Oculomotor nerve (CN III) (4)
1) Motor nerve
2) Eye movement
3) Somatic motor (voluntary)
a) Super, inferior, medial rectus of eye
b) Inferior oblique of eye
4) Visceral motor (involuntary)
a) Pupil dilation
Trochlear nerve (CN IV)
Somatic motor nerve controlling superior oblique of eye
Trigeminal nerve (CN V) (3)
1) Mixed motor and sensory nerve
2) Responsible for chewing and sensation of the face, nose and mouth
3) Three branches:
a) Opthalmic - sensory, forehead and eyebrows, upper nose
b) Maxillary branch - sensory, sensation of skin on lower eyelids, upper lip, upper gums, upper teeth and lips, and pharynx
c) Mandibular - mixed, Sensation - lower gums, teeth and lips, including heat cold and pressure for tongue. Motor - muscles of mastication
Abducens nerve (CN VI)
Motor nerve responsible for eye abduction (outward) and lateral rectus
Facial nerve (CN VII) (4)
1) Mixed motor and sensory nerve
2) Somatic motor - responsible for facial expressions
3) Sensory - sensation of tongue and taste on the anterior portion of the tongue
4) Visceral motor - lacrimal (tear) glands and nasal mucous glands
Vestibulocochlear (CN VIII) (2)
1) Special sensory nerve
a) Vestibular branch - balance and equilibrium
b) Cochlear - hearing
2) Travels through internal acoustic meatus
Glossopharyngeal nerve (CN IX) (2)
1) Mixed motor and sensory
a) Motor - swallowing
b) Sensory - taste on posterior portion of tongue
2) Visceral motor - neurons that control the parotid salivary glands
Vagus nerve (CN X)
1) Mixed motor and sensory nerve
2) Spreads out widely in the abdomen
3) Responsible for digestion, regulation of heart rate, sensation of digestive tract
Accessory nerve (CN XI) (also called spinal accessory)
Motor nerve responsible for control of muscles involved in rotation of head and movement of upper shoulders
Hypoglossal nerve (CN XII)
Motor nerve responsible for voluntary tongue movements
Cranial Nerve Memory Tool Graphic (Memorize)
Cranial Nerve Picture (Memorize)
Nerve (2)
1) Found in PNS
2) Hundreds of thousands of axons wrapped together in connective tissue
Ganglia (2)
1) Found in PNS
2) Clusters of nerve cell bodies in the PNS
Spinal nerves (6)
1) 31 pairs total
2) Cervical - 8 pairs (C01-C08)
3) Thoracic - 12 pairs (T01-T12)
4) Lumbar - 5 pairs (L01-L05)
5) Sacral - 5 pairs (S01-S05)
6) Coccygeal - 1 pair
Spinal nerve roots
1) Dorsal root - axons of AFFERENT sensory neurons
2) Ventral root - Axons of EFFERENT motor neurons
3) Join together - ALL spinal nerves are mixed sensory and motor
Dorsal ramus (3)
1) Serves dorsal trunk
2) Carries visceral motor, somatic motor, sensory information
3) Skin, muscles of back
Ventral ramus (4)
1) Ventral trunk
2) Upper/lower limbs
3) Visceral motor, somatic motor
4) Body surface, body wall, limbs
Plexus (2)
(1) Network of interconnecting nerves
2) Cervical, brachial, lumbar and sacral
Afferent Signals
1) Received by spinal nerves
2) Signal passes through dorsal roots
3) Into spinal cord
4) Up to brain for processing
Efferent signals (5)
1) Decision in the brain is made to move
2) Signal passes down the spinal cord
3) Out to the appropriate spinal level
4) Out the ventral root to destination
5) For voluntary motor contraction
Dermatome (2)
(1) Region of skin that carries sensory information through a specific pair of spinal nerves
2) Include cervical, thoracic, lumbar, sacral
Cervical plexus
Combination of the ventral rami of spinal nerves C1-C5
Phrenic nerve (4)
1) Most important nerve of cervical plexus
2) Supplies motor and sensory fibers to diaphragm
3) Irritation of this nerve causes hiccups
4) Severing nerve would paralyze diaphragm, which would require a ventilator (mechanical respirator)
“Three four five keeps the diaphragm alive”
Phrenic nerve in C3-C5 keeps diaphragm alive
Brachial plexus (4)
1) Ventral Rami of Spinal Nerves C5-T1
2) Roots combine to form three trunks:
a) superior
b) middle
c) inferior
Trunks form two divisions:
a) anterior
b) posterior
Divisions branch into three cords:
a) lateral
b) posterior
c) medial
Axillary nerve (Brachial Plexus) (2)
1) Motor to three muscles:
a) Deltoid
b) Teres minor
c) Long head of the triceps brachii
2) Sensory information
a) from shoulder joint
Radial nerve (Brachial Plexus) (2)
1) Motor to muscles:
a) Triceps brachii
b) 12 muscles of forearm for wrist and finger extension
2) Sensory information
a) Associated joints and overlying skin
Median nerve (Brachial Plexus) (2)
1) Muscles:
a) Flexor muscles of the forearm
b) Thenar muscles (thumb)
2) Sensory information
a) Skin on digits 1-3 and 1/2 of digit 4
Ulnar nerve (Brachial plexus) (2)
1) Muscles:
a) Flexor muscles of the forearm, wrist and hand
2) Sensory information
a) Skin on 1/2 of digit 4 and 5
Musculocutaneous nerve (Brachial plexus) (2)
1) Muscles
a) Flexor muscles of elbow
b) Biceps brachii
c) Brachialis
2) Sensory
a) Skin on radial side of forearm
Lumbar plexus (3)
1) Ventral rami of L1-L4
2) Anterior division
3) Posterior division
Femoral nerve (Lumbar plexus) (2)
Muscles:
a) Hip flexors
b) Knee extensors
Sensation:
a) Skin on the anterior thigh
Lateral femoral cutaneous nerve (Lumbar Plexus)
Sensation
a) Skin on anterior, lateral, posterior surfaces of thigh
Saphenous nerve (Lumbar Plexus)m m
Sensation:
a) Skin from the medial surface of the leg
Sacral Plexus (2)
1) Ventral rami of L4-S4
2) Sciatic nerve
a) Largest nerve in body
b) Inferior trunk, posterior surface of thigh
Sciatic nerve branches
1) Common fibular (peroneal) nerve
a) Travels laterally
2) Tibial nerve
a) Travels along posterior surface of tibia
Autonomic Nervous System (3)
1) Division of the PNS
2) Motor neurons that control internal organs
a) Automatically
b) No conscious intervention needed
3) Sensory neurons come from internal organs
a) Cell bodies are in the DRG (Dorsal Root Ganglion)
b) With cell bodies for somatic sensory neurons
Ganglia
Clusters of nerve cells in the PNS
Preganglionic axon (2)
1) A motor neuron cell body located in the spinal cord and brain.
2) This axon synapses with a second motor neuron located in the autonomic ganglion outside the spinal cord
Postganglionic Axon
After synapsing in an autonomic ganglion, the axon of the ganglionic motor neuron synapses on an effector organ in the PNS
The Sympathetic System (2)
1) Also called thoracolumbar division
a) Contains preganglionic fibers from thoracic and lumbar segments of the spinal cord
2) Widespread targets
a) Cover large regions and has many effects
Sympathetic “fight or flight” response (3)
Fight or flight response:
a) Muscles need steady, increased supply of glucose and oxygen
b) Accelerates heart beat
c) Dilates bronchi
2) Liver
a) Breaks down glycogen to glucose
3) Digestion
a) Inhibited
Sympathetic system neurotransmitter
Noropinephrine (NE)
Sometimes called adrenergic
Sympathetic Trunk Ganglia (3)
1) Located on both sides of the spinal cord
2) Contain ganglia for the sympathetic nervous system
3) Controls effector organs in the trunk, head and limbs
Celiac Ganglion (Sympathetic System) (2)
1) Largest
2) Controls digestive tract
Superiormesenteric Ganglion (Sympathetic System) (2)
1) Small intestine
2) Parts of large intestine
Inferior Mesenteric Ganglion (Sympathetic System) (2)
1) Large intestine
2) Kidneys
3) Bladder
4) Sex organs
Parasympathetic System
1) Also called craniosacral division
a) Contains preganglionic fibers from the brainstem and sacral divisions of the spinal cord
2) More specific targets
Parasympathetic system functions
1) Called housekeeper system
a) Responses associated with a relaxed state
2) Pupil constriction
3) Slows heart rate
4) Promotes digestion
a) Secretion of digestive glands
b) Smooth muscles of GI tract
Parasympathetic system neurotransmitter (2)
1) Acetylcholine (ACh)
2) Called Cholinergic
Ciliary ganglion (Parasympathetic system) (3)
1) CN III
2) Intrinsic eye muscles
3) Pupil/lens changes
Pterygopalatine & Submandibular ganglion (Parasympathetic system) (4)
1) CN VII
2) Organs for tear production
3) Nasal glands
4) Salivary glands
Otic ganglion (parasympathetic system)
1) CN IX
2) Parotid glands (salivary production)
Intramural ganglion
1) CN X
2) Visceral organs in thoracic cavity
Traumatic Brain Injuries (TBI) (2)
1) Head is moving and suddenly stopped
a) Head hits an object
b) MVA (Motor Vehicle Accident)
c) Sports
d) Fall
2) Brain damage locations
a) Site of impact
b) Also the opposite side of the skull due to recoil
Concussion (2)
1) Slight TBI, effects usually temporary but minor effects can linger
2) Symptoms tend to be mild and transient
a) Dizziness
b) Brief loss of consciousness
c) Heads - can linger
d) No permanent neurological damage
Contusion (2)
1) Significant neuronal tissue damage
2) Symptoms tend to be more severe
a) Unconsciousness (coma)
b) Hours to lifetime
Hemorrhage (2)
1) Following a head injury
a) Causes blood to accumulate in the skull
2) Intracranial pressure
a) Pressure available inside the skull
b) This is limited due to the enclosed skull
c) Rises after hemorrhage
Brain injury impacts (2)
1) Damage to brain tissue
a) Compression of brain tissue
2) Forces brain stem down through the foramen magnum
a) Damage to brain stem
b) Decreased control of heart rate
c) Respiration is lost
d) Fatal without intervention
Parkinson’s Disease
1) Disorder of the Basal Ganglia
2) Apraxia - impaired motor planning
a) rigid movements
b) Difficulty executing a motor plan
Ataxia (4)
1) Injury to the cerebellum
2) Unlike apraxia, motor planning is not impaired, but motor coordination is impaired
3) Impaired motor coordination
a) Smooth gait impaired
b) Slurred speech
4) Like being drunk
CVA (Cerebrovascular accident) (3) (Also called a stroke)
1) Blood circulation blocked within the brain
2) Brain tissue dies due to lack of oxygen and nutrients
3) Severity depends on vessel blocked (Larger vessel = more damage)
Hemorrhagic CVA (2)
1) Brain bleed
2) Blood vessel in brain ruptures
Ischemic CVA
1) Blockage in artery
a) Clot (Embolus)
b) Fat deposit
TIA (Transient Ischemic Attack
Small clot causes a temporary blockage in flow, but then resolves
Stroke symptoms (2)
1) Severe strokes are often fatal
2) Stroke survivors
a) Depends on area of brain impacted
b) Paralysis
c) Cognitive changes
d) Speech impairment
e) Emotional changes
Stroke recovery (2)
1) Neural plasticity
a) Undamaged neurons in the surrounding area spread into the area of injury
2) Recovery through physical rehabilitation
a) Physical, occupational, speech therapy
b) Teaching other areas of the brain to learn new functions for lost brain tissue
Stroke signs (America Stroke Association)
Act FAST
1) Facial drooping
2) Arm weakness
3) Speech difficulty
4) Time to call 911
Alzheimer’s Disease (2)
1) Progressive degenerative disease of the brain
2) Results in mental decline, until the brain can no longer control basic bodily functions
Alzheimer’s Disease mechanics
1) Decreased brain tissue seen in the brain
2) Structural changes in the brain
a) Formation of plaques
b) Entanglement of neurons
c) Lack of neural firing
d) Leads to neuron death
3) Spreads through all brain tissue
4) Leads to shrinkage of cerebral cortex gray matter
Alzheimer’s Disease stages
1) Early - Difficulty remembering newly learned information
2) Mid - Brian loss interferes with basic memory skills
a) Mood, behavioral changes (frontal lobe)
b) Disorientation to surroundings
c) Often stressful for caregivers
3) Late - Person has difficulty speaking, swallowing, walking
Amyotrophic lateral sclerosis (ALS) (2)
1) Rare neuromuscular condition
2) Progressive destruction of ventral horn motor neurons, causing paralysis and loss of ability to eat, speak, swallow and eventually breathe
Paralysis (2)
Occurs in all areas controlled BELOW the spinal cord injury
1) Paraplegia (lower limb paralysis) may occur if spinal cord is injured between T1 and L1
2) Quadriplegia may occur if spinal cord is injured in cervical region
Carpal tunnel syndrome (2)
1) Caused by compression of the median nerve
2) Decreased sensation in first three digits and half of fourth digit in hand
Claw hand (2)
1) Caused by ulnar nerve damage
2) Inability to open fourth and fifth fingers caused by flexion at the IP joints and hyperextension of the MCP joints in digits 4 and 5
Sciatica (2)
1) Caused by increased pressure on sciatic nerve from surrounding muscles
2) Pain following the path of the sciatic nerve int he lower pelvis and posterior thigh
