L1 Nervous System Flashcards
CNS
Brain and spinal cord
Integrates and coordinates incoming and outgoing neural signals
PNS
Nerves and ganglia
Consists of nerves that conduct impulses to or away from CNS to the rest of the body
Not protected/exposed to toxins & mechanical injuries
Meninges
Three connective tissues that protect, suspend, and surround the CNS within vertebral column/cranial cavity
Dura mater (outer)
Arachnoid mater
Pia mater
Epidural space
Outside dura mater
Contains fat, vertebral venous plexus
Drugs can be administered here
Subdural “space” and arachnoid
Potential space if there’s blood accumulation or a pathology
Dura and arachnoid maters are usually together
Subarachnoid space
Below arachnoid
Contains cerebrospinal fluid
Access via lumbar puncture
Pia mater
Can’t pull of spinal cord
Denticulate ligament
Lateral to pia mater
Anchors spinal chord within spinal canal
Spinal cord lies within
Vertebral column
Vertebral column components
7 cervical 12 thoracic 5 lumbar 5 sacral (fused) 3-4 coccygeal (fused)
Spinal cord does not extend
The entire length of vertebral column
Conus medullaris
Inferior termination on spinal cord
~L1-L2 vertebral level in adults
Filum terminale internus
Proceeds downward from conus medularis
Delicate strand of fibrous tissue
PNS components
12 pairs cranial nerves
31 pairs spinal nerves
(left and right of each)
Spinal nerves
C1-C8 8 cervical
T1-T12 12 thoracic
L1-L5 5 lumbar
S1-S5 5 sacral
Co1 1 coccygeal
Spinal cord segment
Portion of spinal cord that is associated with one pair of spinal nerves
A single spinal nerve contains
Dermatome and myotome
Dermatome
Segment of skin receiving sensory interaction
Go through posterior root towards CNS
Myotome
Segment of skeletal muscle receiving motor innervation
Go through anterior root away from CNS
Anterior root
Only contains motor info
Away from CNS
Posterior root
Only contains sensory info
Info to CNS
Posterior horn
Cell body in PNS
Anterior horn
Cell body in CNS
Spinal nerve contains
Motor and sensory info
Posterior root ganglion
Contains cell bodies of sensory neurons
Posterior ramus
Contains motor and sensory information
Anterior ramus
Contains motor and sensory information
Plexus
Combines neurons from different sources or spinal cord levels to form nerves with specific targets
Anterior rami can
Form plexuses (many do)
Or travel around body wall singularly
Spinal nerves exit vertebral column
Nerve C1 between skull and C1 vertebrae
Nerves C2-C7 emerge superior to corresponding vertebrae
Nerve 8 emerges inferior to C7 vertebrae
Nerves T1 and below emerge inferior to corresponding vertebrae
Because spinal cord is much shorter than vertebral column
Spinal nerve roots become longer and pass more obliquely toward the inferior region of the vertebral canal
Cauda equina
“Horses tail” of spinal nerves after conus medullaris
CFS can be withdrawn safely via
Lumbar puncture between L2 and S2
Pia mater ends
At conus medullaris
Dural sac ends
At S2
And external filum terminale proceeds from here
Above dural sac = internal filum terminale
Neuron and its components
Specialized cell to transmit info
Cell body
Dendrite(s)
Axon
Neuron terminology of CNS
Nucleus - collection of cell bodies in CNS
tract- collection of neuron processes (axons) in CNS
Neuron terminology PNS
Ganglion - collection of cell bodies in PNS
Nerve - collection of neuron processes (axons or dendrites) in PNS
Structural types of neurons
unipolar
Bipolar
Pseudounipolar *
Multipolar *
Neurons classified by direction of impulse
Efferent
Afferent
Efferent
Motor
CNS to PNS
Afferent
Sensory
PNS to CNS
Neurons classified by type of structure innervated
Somatic
Visceral
Somatic
Skin, skeletal muscle, bones, joints
Framework
Protection
Voluntary movement
Visceral
Organs, glands, blood vessels
Involuntary activities
Carry out internal functions like digestion, excretion, and respiration
Four functional types of neurons
SA
VA
SE
VE
SA
Somatic afferent
Body wall and sensory
VA
Visceral afferent
Organ system and sensory
SE
Somatic efferent
Body wall and motor
VE
Visceral efferent
Organ system and motor
Nerve structure
Neurons + connective tissue covering + vessels
