Nervous System Flashcards
What structures make up the CNS?
Brain and spinal cord
What is the structural organization of the Nervous System?
It can be divided into the Central Nervous System (CNS) and the Peripheral Nervous System (PNS)
What structures make up the PNS?
Spinal nerves (31) and cranial nerves (12)
What is the functional division of the Nervous System?
It can be divided into the Afferent Sensory division and the Efferent Motor division
What can the Afferent Sensory Division be divided into?
Somatic sensory- information from skin, joints, skeletal muscle, special senses, fascia
Visceral sensory- information from the viscera/organs
What can the Efferent Motor Division be divided into?
Somatic Motor- voluntary nervous system (skeletal muscles)
Autonomic Motor- involuntary nervous system (smooth muscle, cardiac muscle, and glands)
How does information travel via the Afferent Sensory CNS?
Information travels to the CNS from the body
How does information travel via the Efferent Motor CNS?
From the CNS to the rest of the body
What are the 3 cell types that make up the Nervous System?
- Schwann Cells
- Neuroglia Cells (Glial Cells)
- Neurons
What are Glial cells (neuroglia)?
Non-excitable cells that are for support, insulation, and nourishment of neurons
What are Schwann Cells?
These are the glial cells the of the PNS
What do Schwann Cells produce?
Myelin protein for myelinated axons
What is the relationship between Schwann Cells and axons?
Schwann Cells will encase the axon- groups of up to 10unmyelinated axons can be encased by 1 Schwann cell
What is an oligodendrocyte?
It is the type of glial cell in the CNS and is the equivalent of the Schwann cell in the PNS
What is Myelin and what is its function?
Myelin is layers of protein and lipid that forms a sheath around some axons and increases the speed of the impulse transmission between neurons
What is the structural and functional unit of the nervous system?
Neuron
What is the function of the neuron?
Specialized for rapid communication
What are the components of a neuron?
Cell body (soma, Perikarya)
Dendrite
Axon- can be myelinated or unmyelinated
What does a dendrite do?
Carry impulses to the neuron cell body
What does an axon do?
Carry impulses away from the neuron cell body
What is a synapse?
The point at which one neuron communicates with one or more neurons
What facilitates the communication between neurons?
Neurotransmitters
What are some neurotransmitters?
Acetylcholine
Norepinephrine
Dopamine
GABA
What is the nucleus in the CNS?
It is a collection of neuron cell bodies
Where is gray matter located in the CNS?
Nucleus
What is a tract?
It is a collection of nerve fibers that connect nuclei and is found only in the CNS
What is a ganglion?
It is a collection of nerve cell bodies and is only present in the PNS (outside the CNS)
What are peripheral nerves?
A collection of nerve fibers that connect the CNS with peripheral structures, spinal nerves, or cranial nerves
Where does the spinal cord begin?
At the medulla of the brain stem
Where does the spinal cord end?
At the L1-L2 vertebrae in adults and L2-L3 vertebrae in children
What is the spinal cord?
A long and thin tube shaped bundle of nerve fibers
What is the primary function of the spinal cord?
Transmit signals to and from the brain to peripheral structures
What is the shape of the spinal cord in the cervical region?
It is large and oval shaped
Is there a large amount or a small amount of white matter in the cervical spinal cord and why?
There is a large amount of white matter because all motor information that needs to pass to the body needs to go through the cervical region
What is gray matter?
It is a component of the CNS made up of nerve cell bodies and few myelinated axons
What is white matter?
It is a component of the CNS that is made up of glial cells and myelinated axons and few cell bodies
Is there a large amount or a small amount gray matter in the cervical region and why?
There is a small amount of gray matter because the cervical region is mostly sensory and gray matter is mostly for motor information (descending (motor) tracts have not excited the spinal cord)
What is the shape of the thoracic spinal cord?
It is oval shaped but smaller than the cervical region
The thoracic region has which horn of gray matter?
Lateral horn which contains part of the autonomic NS
What cell bodies are located in the thoracic spinal cord?
Cell bodies of the sympathetic nervous system
What is the shape of the lumbar spinal cord?
Round in shape and large
Does the lumbar region contain a large amount or a small amount of gray matter and why?
It has the largest amount of gray matter because it is more for the motor function of the lower limbs
What is the shape of the sacral spinal cord?
Similar to the lumbar spinal cord but smaller
Descending and ascending tracts of the sacral spinal cord
Most Descending tracts have excited the spinal cord
Many Ascending tracts have not yet entered the spinal cord
What are the 3 meninges of the spinal cord?
Dura mater
Arachnoid mater
Pia mater
What is dura mater?
It is the thick and fibrous outermost layer of the spinal cord
What separates the dura mater and the spinal cord?
Epidural space
What does the dura mater form?
The spinal dural sac
What pierces the dural sac?
Spinal nerves
At which region of the vertebral column does the dura mater end?
S1/S2
What anchors the dural sac to the coccyx?
Film terminale
What is arachnoid mater?
The delicate and vascular middle layer of the spinal cord
What is the subarachnoid space?
The space between the arachnoid mater and the pia mater
What is in the subarachnoid space?
CSF
What is CSF?
Cerebrospinal fluid
It is a clear and odorless fluid that is low in protein and cellular content and it is a cushion for the cord
What is pia mater?
It is the inner most layer of the spinal cord and is also the most delicate layer- it closely follows the surface of the cord
Pia mater
This layer directly covers the spinal nerve roots and blood vessels and it continues as the filum terminale
What is filum terminale?
It is a continuation of pia mater coming off of the conus medullaris after the spinal cord has ended- it pushes through the dural sac taking pia and arachnoid matter with it
What does the filum terminale do?
It anchors the spinal cord to the coccyx
What is the denticulate ligament?
Sheets of pia mater that runs longitudinal to the cord
What is the function of the denticulate ligament?
It anchors the spinal cord to the dural sac and it separates the posterior and anterior roots
How many total spinal nerves are there?
31
Where do the cervical spinal nerves exit?
From the intervertebral foramina above the named segment and C8 exits above T1
Where do the thoracic spinal nerves exit?
The intervertebral foremen below the named segment
Where do the lumbar spinal nerves exit?
The intervertebral foremen below the named segment
What do spinal nerves do?
They carry posterior (Afferent/sensory) and anterior (efferent/motor) information from 1 spinal segment
Where do the dorsal and ventral root run?
In the subarachnoid space
What meningeal layer covers the spinal nerves?
Pia mater
What meningeal layer do the spinal nerves pierce?
Dura mater
What are the 3 connective tissue coverings of the peripheral nerves?
Epineurium
Perineurium
Endoneurium
What does the epineurium enclose?
It encloses the bundle of fascicles including fat, blood vessels, amd lymphatics- this is the outermost covering
What does the perineurium enclose?
Dense tissue around one fascicles to protect it against foreign substances- this is the middle layer
What does the endoneurium enclose?
It is a delicate sheath that encloses a neurolemma and cells- this is the inner most layer
What forms the brachial plexus
C5-T1
What does the brachial plexus innervate?
The upper extremities
What forms the lumbosacral plexus?
It is formed by the lumbar and sacral nerve roots of L1-S5
What does the lumbosacral plexus innervate?
The lower extremities
What is the lumbar cistern?
An enlargement of the subarachnoid space to accommodate the cauda equina
What is a dermatome?
An area of skin innervate by a single spinal nerve
What is a myotome?
Muscle receiving Innervation from a single spinal level
What are the 3 longitudinal arteries that run from the brain stem to the conus medullaris and supply the superior spinal cord?
The 1 anterior spinal artery and 2 posterior spinal arteries
Where is the anterior spinal artery from?
Branches of the vertebral artery
Where are the posterior spinal arteries from?
Vertebral or posterior inferior cerebellar artery
What arteries supply most of the spinal cord?
Segmental medullary and radicular artery
Which artery reinforces circulation to 2/3 of the cord?
Greater anterior segmental medullary artery
Which artery supplies the nerve roots?
Anterior/posterior radicular arteries
How many spinal veins are there?
3 anterior spinal veins and 3 posterior spinal veins
How do the spinal vein run?
They run longitudinally and communicate freely with each other
What drains the spinal veins?
The 12 anterior and posterior medullary and radicular veins
What do the spinal veins form?
Internal vertebral venous plexus in the epidural space which communicates with dural venous sinuses and veins of the cranium
