Nervous System Flashcards
Functions
sensory input, integration, motor output, cognition, emotion, arousal
Nervous System Cells
2 types: neuron and glial cell
Neuron
basic functional cell of the nervous system
Role of neuron
process and transmit information through chemical and electrical signaling
Glial (neuroglial)
smaller, outnumber neurons, do not participate in signaling but are essential to function
Role of glial cells
repair neuron after injury, maintain proper ionic environment, modulate electrical conduction
Neuron parts
soma, dendrite, axon, axon hillock
Soma
cell body
Dendrite
branched projection of neurons, receives synaptic input from other neurons
Axon
nerve fiber, long projection of the nerve cell that conducts electrical impulses away from the soma
Axon hillock
part of the soma that connects to the axon, where synaptic signals are summed before being transmitted
Multipolar Neurons
on axon, many dendrites, allows a lot of information to be received and integrated. ex: motor cells
Bipolar Neurons
have two projections, axon on one side and dendrite on the other. ex: special senses, retina of eye
Unipolar/pseudounipolar
start bipolar, then become unipolar, sit in dorsal root ganglia. ex: general sensory stuff
Gray vs. White Matter
gray: neurons, outside
white: axons, inside. Axons are myelinated, myelin is white, thus the “white” matter. Opposite in spinal cord
CNS
brain and spinal cord
PNS
peripheral nerves, connects CNS to rest of body
Cerebral cortex lobes
plans and executes activity and movements. central sulcus divides the frontal and parietal lobe.
Solci
depressions
Gyri
upper folds
Homonculus
little person, the amount of tissue devoted to a given body area, and is proportional to how richly integrated it is. Right side of homonculus controls left side of body, and left homonculus controls right side of body
Cranial nerves
come out of brain stem and do stuff for your face
conus medullaris
where spinal cord ends around L1, shaped like a cone
cauda equina
innervations coming off and into respective segments
filum terminale
connective tissue that come from conus medullaris down into tailbone
spinal cord
in cervical and thoracic vertebrae there is more white matter, but as you get down into lumbar, there is more gray matter. As you go down, less white (myelin) because there is less distance to travel
dorsal (posterior) root
afferent (sensory)
ventral (anterior) root
efferent (motor)
spinal nerve
where ventral and dorsal root meet. Here it exits the vertebral column and splits into two rami.
rami
contain both sensory and motor info. Dorsal and ventral rami
dorsal rami
supply the back
ventral rami
supply the limbs and anterolateral trunk. Only these rami enter into formation of nerve plexi
Pathway
rootlet, root, spinal nerve, rami
Spinal nerves
C: 8, T: 12, L: 5, S: 5, Coccygeal: 1
Positioning
spinal cord descends in space between vertebral bodies and articular processes. The rami come out of the intervertebral foramen
Which rami enter into formation of the nerve plexi?
ventral rami only
Nerve plexus
network of intersecting nerves, combine ventral rami of spinal nerves into one nerve, both motor and sensory nerves
Why nerve plexus?
protection in the event of an injury: if one spinal nerve was ever cut, you don’t lose innervation to that area, because you have others in that plexus.
Brachial plexus
formed by nerves C5-T1, supplies upper extremity
Lumbosacral plexus
lumbar plexus formed by nerves L1-L4, goes to front of leg
sacral plexus formed by nerves L4-S3, goes to back of leg
supplies lower limbs
Dermatome
area of skin innervated by afferent fibers of a single spinal nerve. Basically a skin bet of sensory innervation. Overlap for similar reasons to plexi
Adjacent dermatomes
overlap so that if one nerve is sectioned, the area will not completely lose sensation
Cutaneous vs. dermatome innervation
dermatomes are isolated, while the cutaneous innervation is combined. Dermatome is spinal level (i.e. herniated disc), cutaneous is peripheral level (more broad)
PNS Subdivisions
somatic and visceral, both are motor (efferent) and sensory (afferent)
Somatic
consists of nerves that carry conscious sensation from peripheral regions back to CNS, nerves that innervate voluntary muscle. Involved with receiving and responding to information from external environment
Visceral
consists of nerves that monitor changes in viscera, nerves that innervate smooth muscle, cardiac muscle, and glands. Involuntary, detect and respond to information from internal environment
Autonomic nervous system
part of visceromotor, includes sympathtic and parasympathetic. Affects heart and respiratory rate, pupil dilation, perspiration, and sexual arousal. Mostly involuntary, but can have some degree of conscious control (i.e. swallowing)
Sympathetic
fight or flight, quick response mobilizing system
Parasympathetic
rest and digest, more slow acting dampening system, but is not totally inhibiting
