CNS: The Brain & Spinal Cord Flashcards
Protection of CNS is called? What does it contain? location?
Meninges
- 3 connective tissue layers
- btwn skull/vertebrae & brain/spinal cord
3 protective connective tissue layers are?
Dura Mater
Arachnoid Mater
Pia Mater
Dura Mater
description?
function?
contains?
superficial (outside) layer, strongest
connects to periosteum of bones
contains Dural Sineses
what are dural sinuses?
function?
spaces within the dura mater
drains blood from brain to neck veins
Arachnoid Mater
Avascular (no blood circulation), middle layer
Protection- Cerebrospinal Fluid
description? functions? movement? formed?
clear, colorless liquid
protects against chemical & physical injuries
carries 02, glucose, & chemicals from blood to neurons & neuroglia
continuously circulates through subarachnoid space
formed in the ventricles (4) of the brain
whats the subarachnoid space?
its the space btwn arachnoid & pia mater
Where is Cerebrospinal fluid formed?
formed in the ventricles of the brain
- substances filtered from blood plasma & secreted through ependymal cells
- (mostly water)
Pia Mater
description? location? function?
thin, transparent
adheres tightly to brain & spinal cord surfaces
vascular (blood circulation) - nutrient supply
CSF stands for ?
Cerebrospinal Fluid
CSF Functions (3)
Mechanical protection
Chemical protection
Circulation
Mechanical Protection of CSF involves? (function)
shock absorber
Chemical Protectionof CSF involves? (function)
Maintains optimal chemical environment w/ ions
Circulation of CSF involves? (function)
Provides exchange of nutrients & wastes btwn blood & nervous tissue
White Matter of CNS
bundles of mylinated & unmyelinated axons
Gray Matter of CNS
contains dendrites, unmyelinated axons, axon temirnals, & neuroglia
Gray vs White Matter of CNS ?
White matter- has MYELINATED (& unmyelinated) axons
Gray matter- only has UNMYELINATED axons
Spinal cord consists of : (3)
1) bony vertebral column (bones & vertebrae, 31 spinal nerves)
2) Meninges
3) Epidural space
What’s the epidural space?
location? function?
(gap) spinal cord consists of this
- space btwn dura mater & vertebral column
- consists of fat & connective tissue for protection
spinal cord anatomy, how is it divided?
divided into right & left halves
what are the 2 divisions of the spinal cord?
Anterior (ventral) median fissure
Posterior (dorsal) median fissure
fissure
groove, fold or slit
sulcus
groove or depression btwn 2 parts
difference btwn fissure & sulcus
fissure- shallow cut
sulcus- deeper cut
spinal cord anatomy, white & gray matter
white matter surrounds ‘H shaped’ gray matter
central canal in center of gray matter, contains CSF!
Gray matter
how is it divided?
divided into regions called: horns
what are the 3 divisions (horns) of gray matter?
posterior (dorsal) gray horn
anterior (ventral) horn
lateral gray horn
Posterior (dorsal) gray horn
- cell bodies & axons of INTERNEURONS - send impulses to other parts of spinal cord & brain
- axons of incoming sensory neurons
Anterior (ventral) gray horn
cell bodies & axons of SOMATIC MOTOR (movement) neurons (MUSCLE CONTRACTION)
Lateral gray horn
-cell bodies of AUTONOMIC MOTOR neurons that regulate cardiac, smooth muscle, & gland activities
-only in thoracic & upper lumbar spinal region
(EX: heart beat, breathing, digestion)
Function of gray matter in spinal cord
receives & integrates incoming & out going information
White matter how is it organized?
organized into: anterior columns lateral columns posterior columns (COLUMNS NOT HORNS) (white matter- cheese strings=columns (made up of tracts))
white matter, what does each column contain?
each column contains 1 or more tracts
tract
bundles of axons carrying same info to same destination
what are the 2 tracts of white matter?
Sensory (Afferent) Tracts
Motor (Descending) Tracts
Sensory (Ascending) Tracts
sends impulses toward brain (touch, pain, pressure, sound, etc)
Motor (Descending) Tracts
sends impulses down the spinal cord (in response to stimuli)
Function of White Matter in spinal cord
propagates sensory impulses from receptors to brain
sends motor impulses from brain to effectors (muscles, glands)
Spinal Roots
location? purpose?
axons of neurons extend from spinal cord to converge to form ‘roots’
connect each spinal nerve to a segment of the cord
What are the 2 spinal roots?
Anterior or Ventral Roots
Posterior or Dorsal Roots
Anterior or Ventral Roots
what neurons are involved? what do they do?
motor neurons
conduct impulses from CNS to effectors
Posterior or Dorsal Roots
what neurons are involved? what do they do?
Sensory neurons
conduct impulses from sensory receptors into CNS
Dorsal root ganglion- cell bodies of sensory neurons
what is it called when the Anterior or Ventral Roots & the Posterior or Dorsal Roots form?
when they meet, they form spinal nerves
what are the spinal roots function?
2 bundles of axon (called roots) connect each spinal nerve to spinal cord
Posterior or Dorsal Roots
contain?
impulses from…?
contain ONLY sensory axons
-impulses from sense receptor in skin, muscles, and internal organs
Anterior or Ventral Roots
contain?
impulses from…?
contain axons of motor neurons
-conduct impulses from CNS to muscles & glands
Spinal Reflexes
description? help do what?
fast, involuntary response to a stimulus
-can be inborn or learned behavior
help maintain homeostasis by controlling involuntary processes
type of reflexes? (4)
spinal reflex
cranial reflex
somatic reflex
autonomic (viseral) reflex
spinal reflex
description & example
integration in spinal cord gray matter
EX: knee jerk reflex (patellar reflex)
cranial reflex
description & example
integration in brain stem
EX: eye movement (like blinking)
somatic reflex
example
EX: muscle contraction
autonomic (viseral) reflex
description
responses of smooth muscle, heart, & glands
AUTOMATIC
pathway followed by nerve impulses that produce a reflex (5 steps)
1) stretching stimulates sensory receptor (muscle spindle) (dendrites recept, stimulus produces graded potential)
2) sensory neuron excited (relay neurons to send impulse to area of brain for conscious awareness, axon to gray matter of spinal cord or brain stem (afferent neurons))
3) within integrating center (gray matter of spinal cord), sensory neuron activates motor neuron (processes impulse)
4) motor neuron excited (transmit impulse from CNS to part of body)
5) effector (muscle or gland) contracts & relieves the stretching
reflex arcs allow for what?
fast, involuntary processing & responses to stimuli
spinal vs cranial reflexes
spinal occur in the spinal cord
cranial occur in the brain
are reflexes internal or external?
both internal & external
spinal cord extends from _______ of the skull to the ______ region of the vertebral column.
brain stem (foramen magnum or base of the skull) lumbar region
meninges cover spinal cord, extend more inferiorly to form a sac from which CSF can be withdrawn without damage to the spinal cord. this procedure is called a
spinal tap
how many pairs of spinal nerves arise form the cord?
31
of the 31, how many pairs are cervical?
8
of the 31 spinal nerves, how many pairs are thoracic?
12
of the 31 spinal nerves, how many pairs are lumbar?
5
of the 31 spinal nerves, how many pairs are sacral?
5
what the order from medulla oblongata to coccygeal for spinal nerves?
Cervical
Thoracic
Lumbar
Sacral
afferent means?
efferent mean?
association neurons mean?
afferent- sensory
efferent-motor
association-interneurons
neuron type found in dorsal horn?
association neurons
neuron type found in ventral horn
efferent, motor
neuron type found in dorsal root ganglion
afferent, sensory
fiber type in ventral root
efferent, motor
fiber type in dorsal root
afferent, sensory
fiber type in spinal nerve
both efferent & afferent
damage to this fiber type would lead to loss of sensory function
afferent
damage to this fiber type would result in motor function loss
efferent
