Nervous System Flashcards
2 kinds of nervous system cells
Neurons
Neuroglia
of cranial nerves
12
of spinal nerves
31
2 divisions of the nervous system
Central
Peripheral
Nuclei
Collection of neurons performing the same task in the CNS
Nerve
Bundle of thousands of axons with associated connective tissue and blood vessels in PNS
Ganglia
Masses of nervous tissue found in PNS
Interneuron
Interconnect with other neurons and are very short
Somatic nervous system
part of PNS containing sensory neurons
Somatic motor neurons
Convey info from CNS to skeletal muscles only
2 divisions of the motor ANS
Sympathetic
Parasympathetic
What cells myelinate axons in the CNS
Oligodendrocytes
What cells myelinate axons in the PNS
Schwann cells
Efferent
Nerve impulses away from CNS
Afferent
Nerve impulses towards CNS
Dendrites
Primary target for synaptic input from other neurons . Opposite end from axon terminal
Hillock
Point of departure of axon
Anterograde Transport
From cell body to axon terminal
2 types of Nerve fibers
Dendrites
Axons
1
Olfactory
O: olfactory epithelium
2
Optic
O: retina
3
Oculomotor
4
Trochlear
5
Trigeminal
6
Abducens
7
Facial
8
Vestibulochlear
9
Glossopharyngeal
10
Vagus
11
Spinal Accessory
12
Hypoglossal
Pneumonic for cranial nerve names
Oh oh oh to touch and feel very green vegetables ah!
Pneumonic for cranial nerve functions (sensory, motor, both)
Some say marry money but my brother says big breasts matter more
What space are neurotransmitters released into
synaptic cleft
Glia
Provide insulation, maintain chemical environment and contribute to the blood brain barrier
Glia: Neuron ratio
3:1
Blood brain barrier
Glia surround blood vessels in the brain and prevent toxins from entering the blood stream
Astrocytes
Glia that mop up neurotransmitters and maintain homesostasis
Microglia
Respond to injury in the CNS and produce inflammatory mediators
2 types of myelinating glia
Oligodendrocytes
Schwann cells
Oligodendrocyte
Part of the CNS– Nodes of ranvier are fewer and more widely spaced allowing for faster transmission
– COIL AROUND SEVERAL AXONS
Schwann cells
Part of the PNS
Associated with only one nerve
Nodes of ranvier are closer together
Number of each type of vertebrae
8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal
How many spinal cord segments per 1 pair of spinal nerves
31
What is the beginning of the PNS
Nerves
Enlargements
Bulges in spinal cord corresponding with attachment of large nerves
Where are the 2 spinal cord enlargments
Cervical– C4-T1
Lumbar-sacral– L1-S2
Conus Medullaris
Tapering end of the spinal cord between L1 and L2 vertebrae
Filum Terminale
Continuation of pia mater. Section is left with no nervous tissue and attaches to coccyx and anchors spinal cord
Caude Equina
(Horse Tail) bundle of spinal nerves and spinal nerve roots, consisting of the second through fifth lumbar nerve pairs, the first through fifth sacral nerve pairs, and the coccygeal nerve
Where should you perform a lumbar puncture
Caude equina– devoid of spinal cord so you can obtain CSF safely
What vertebral section does the spinal cord end at
L1/L2
3 layers of spinal cord coverings
Pia mater
Arachoid mater
Dura mater
Pia mater
Innermost layer that attaches to the spinal cord surface and brain – many blood vessels
Denticulate ligaments
Paired ligaments in pia mater, on either side of the cord, that attach it to the arcachnoid and dura mater
Arachoid Mater
Avascular, middle layer
Dura Mater
(tough mother) Outermost layer extends from foramen magnum to S2 vertebrae
Potential spaces
Space we can use in healthcare
2 spinal cord spaces
Subaracnoid space
Sub dural space
What are spinal cord spaces fllled with
CSF
Epidural layer
Outside of dura mater
2 Epidural effects
Analgesia (decrease pain)
Anesthesia (decrease sensation)
Which spinal cord sulcus is more pronounced
Anterior median
First section in spinal nerve
Root
Spinal nerve
Rootlet– Root– Spinal nerve
Part of the PNS and connects to CNS receptors
Dorsal root ganglion
PNS structure unique to posterior root– First neuron in sensory pathway
White matter
Myelinated axons and tracts send sensory impulses from receptors to brain and motor impulses from brain to effectors
Grey matter
Neuron populations in a butterfly shape recieve and integrate incoming and outgoing information
3 horns of the grey matter in spinal cord
Dorsal
Lateral
Anterior
Dorsal horn
Receives sensory input
Anterior horn
Transmits motor output
Lateral horn
Autonomic NS
Un-myelinated axons
Small and slow
Cervical spinal cord section
Flattened dorso-ventrally
Biggest section
Alot of white matter with large ventral grey horns
Thoracic spinal cord section
Small diameter with small grey matter
- not many muscles here
Lumbar section
Nearly circular
Large ventral and dorsal grey horns
Less white matter
Sacral sponal cord section
Small with alot of grey matter
Posterior root function
Sensory
Anterior root function
Motor
3 layers of the peripheral nerve
Epineurium
Perineurium
Endoneurium
Epineurium
Layer around the entire peripheral nerve with bundles inside
- vascular supply for nerve
Perineurium
Surrounds every peripheral nerve bundle
Endoneurium
Innermost layer of peripheral nerve surrounds axon
Where do axons degenerate following injury
Distal to lesion
Degeneration
Debris is picked up by immune system following injury and myelin is broken up
PNS regeneration
Vigorous and complete
CNS regeneration
Uncommon and never complete
Axotomy
Severing the axon
Wallerian degenration
Axon separates from cell body and degenerates distal to the injury
Where does myelination begin in regeneration
Proximal end
Characteristics of regenerated nerve
More schwann cells and nodes of ranvier = slower
Do cut or crush injuries heal better?
Crush– preserved endoneurium supports better recovery
Necrosis
neuronal death
Glial scar
form in response to CNS injury
3 parts of the brain stem
Midbrain
Pons
Medulla oblongata
Medulla oblongata
Part of brain stem connected to the spinal cord
4 components of the CNS
Spinal cord
Brainstem
Cerebellum
Forebrain
2 parts of the forebrain
Diencephalon
Cerebral hemispheres
Gyrus
Hill
Sulcus
Valley– groovy surface allows for more neurons and more intelligence
3 layers in brain covering
Pia mater
Aracnoid mater
Dura mater
What produces CSF
Choroid plexus
Where are choroid plexuses located
In very brain ventricle
CSF
Optimum environment for chemical signalling, exchnaging nutrients and shock absorption
4 brain ventricles
2 lateral
Third
Fourth
Interventricular formamen
Connects the lateral brain ventricles to the third ventricle
Cerebral aqeduct
Connects the third and fourth brain ventricles
Movement of CSF through brain
Choroid plexus Lateral ventricle Interventricular foramen Third ventricle Cerebral aqueduct Fourth ventricle Central canal and subarachnoid spaces Superior saggital sinus
Medulla
Connects spinal cord to diencephalon
- Transmits everything to spinal cord
Anterior medulla
Motor
Posterior medulla
Sensory
Decussation of pyramids
Crossing of motor tracts in the anterior aspect of medulla oblongata – why brain contorls opposite side of body
Sensory Fasciculi
Ascending sensory axons that go to medial lemniscus
Pons
Ventral to cerebellum
Connects cerebral cortex and spinal cord to cerebellum
What does the pons consist of
Nuclei and tracts
Substantia Nigra
Large, darkly pigmented nuclei in the midbrain that produces dopamine
Substantia nigra in parkinsons
Dead and unpigmented
Cerebral peduncles
Pair of tracts containing motor neurons in the midbrain
Cerebellum
Second largest part of brian with 2 folded hemispheres connected via brainstem
Function of cerebellum
Coordination of complex sequences of movements and regulation of posture and balance
Ataxia
Failure to regulate posture and movement causes uncoordinated movements and speech
Diencephalon
Thalamus and hypothalamus
Involved in sensory and motor processing
Thalamus
Relay station to cerebral cortex where all sensory input enters– carries motor input from cerebellum
Hypothalamus
Regulator of homeostasis, inferior to thalamus
Sensory areas in Cerebrum
Primary visual cortex
Postcentral gyrus
Primary visual cortex
Occipital lobe
Postcentral gyrus
Pariteal lobe
Motor areas of the cerebrum
Pre-central gyrus and Broca’s speech area
2 blood vessels supplying brain
Vertebral artery and internal carotid artery
Circle of willis
circulatory anastomosis that supplies blood to the brain and surrounding structures
6 Vessels in circle of willis
Anterior cerebral artery (2) Anterior communicating artery Internal carotid artery (2) Posterior cerebral artery (2) Posterior communicating artery (2)
Which vessels are not included in circle of willis?
Middle cerebral arteries
Posterior communicating artery
Connects internal carotid and cerebral arteries
Which nerve is part of the cribiform plate of the ethmoid bone
Olfactory
Olfactory bulbs
masses of gray matter
Optic chiasma
Axons from medial half of each eye cross
Optic tract
posterior to optic nerve
Which 3 nerves control muscles that move the eyeballs
Occulomotor
Trochlear
Abducens
Occulomotor
Innervates superior rectus, levator palpebrae superioris and all extrinsic eye muscles
Trochlear
Smallest cranial nerve and only one that comes from posterior brain stem
- innervates superior oblique
Abducens
Originates in the pons and innervates lateral rectus
Trigeminal
Largest cranial nerve, has 3 branches
– Opthalmic, maxillary and mandibular
Opthalmic branch
Smallest trigeminal branch, goes through superior orbital fissure
Maxillary branch
Intermediate size, passes through foramen rotundum
Mandibular branch
Motor neurons for mastication, passes through foramen ovale
Facial nerve
Sensory axons for anterior 2/3 of taste buds
Propiorception
Ability to know your own body and feel position without looking
Vestibulocochlear
Inner ear structures required for equilibrium
4 inner ear structures
Semicircular canals
Saccule
Utricle
Cochlea
Glossopharyngeal
Posterior 1/3 of tatse buds
- sensory to oropharynx
Motor component of glossopharyngeal nerve
Tympanic membrane (ear drum)
Vagus
Longest nerve- travels to gut
- Motor function for pharynx, larynx and soft palate for speaking and swallowing
Spinal Accessory
Brachial motor nerve divided into cranial and spinal accessory
- Innervates sternocleidomastoid and trapezius
Hypoglossal nerve
Motor cranial nerve for tongue muscles
- comes from medulla
2 Motor neurons in ANS
Preganglionic
Postganglionic
Preganglionic neuron
Has cell body in CNS
Autonomic ganglion
Neuronal body outside CNS
- preganglionic axon extends to it
Postganglionic neuron
Cell body within the autonomic ganglion
- unmyelinated axon goes to effector
What neurotransmitter do ANS motor neurons release that somatic motor neurons can’t?
Norepinephrine
Dual innervation
Recieve impulses from both sympathetic and parasympathetic branches
Sympathetic NS
Output to smooth muscle of blood vessels
- Increase alertness and metabolic activity
What grey hron do sympathetic fibers originate from
Lateral horn (T1-L2)
Sympathetic trunk ganglia
Lie in a vertical row on wither side of the vertebral column from the skull to the coccyx
Are pre or post ganglionic axons longer in the SNS?
Post
Where do parasympathetic NS fibers originate from
Cranial nerves 3,7,9,10
S2-4 of spinal cord
Are pre or post ganglionic axons longer in the PNS?
Pre
Pneumonic for actions of the PNS
Salivation Lacrimation Urination Digestion Defecation
5 organs recieving only sympathetic innervation
Sweat glands Arrector muscles in hair Kidney Adrenal medulla Blood vessels
Order of motor pathway
Cerebral cortex Pyramids Decussation of pyramids Ventral horn of spinal cord Muscle
Order of sensory pathway
Dorsal horn of spinal cord Dorsal fasciculi Cerebral penduncles Thalamus Cerebral cortex
Whats on the anterior and posterior medulla
Anterior: Pyramids
Posterior: Sensory fasciculi
2 things on the midbrain
Cerebral peduncles
Substantia nigra
Used CSF gets transported through what structure to get into the superior saggital sinus from the subarchnoid space
Arachnoid villi
Primary Visual Area
Recieves visual information and is involved in visual perception
Broca’s Speech Area
Planning and production of speech
- opposite end of occipital lobe
Central sulcus
Divides the primary somatosensory and motor areas
Primary motor area
Controls voluntary contraction of specific muscles
Primary auditory area
At the base of motor and sensory areas
- closer to occipital lobe than broca’s
Falx cerebri
Extension of dura mater into cerebral hemispheres
- acts as an anchor
Circle of Willis order on diagram from top to bottom
Anterior Cerebral, Anterior communicating
Middle cerebral, Internal carotid
Posterior cerebral, posterior communicating
Vertebral
Anterior cerebral artery territory
Frontal lobe
Middle cerebral artery territory
Parietal lobe
Posterior cerebral artery territory
Occipital lobe