1. Nervous System Flashcards
Central Nervous System (components, function)
Brain, Spinal Cord
Information processing
Peripheral Nervous System (components, function)
12 paired cranial nerves
31 paired spinal nerves
Taking order out of CNS
Nucleus (Nuclei)
Collection of nerve cell bodies in CNS
Tract
Collection of nerve axon (fibers) in CNS
Ganglion (Ganglia)
Collection of nerve cell bodies in PNS
Peripheral Nerve
Collection of nerve cell bodies in PNS
Pathway of Spinal Nerve
spinal cord - ventral/dorsal root- spinal nerve - ventral/dorsal ramus
PNS: Somatic Nervous System
MOTOR –> skeletal muscle
SENSORY
PNS: Autonomic Nervous System
aka Visceral Motor
Involuntary
MOTOR –> smooth muscle (organs, cardiac muscle, glans
2 Neuron pathway
PNS: Visceral Sensory
SENSORY
Ischemia
are you getting any oxygen
AS ME
afferent - sensory
motor - efferent
Somatic Motor Pathway
motor cell bodies in ventral horn of spinal cord- motor fiber (axon) exits via ventral root - spinal nerve - dorsal/ventral ramus - target
VENTRAL ROOT = MOTOR FIBERS ONLY
Ventral Ramus
Innervates majority of body wall
Larger in size than dorsal ramus
Carry sensory and motor fibers
Dorsal Ramus
Innervates small region (duct tape) along dorsal midline
Smaller in size than ventral ramus
Carry sensory and motor fibers
Somatic Sensory Pathway
Skin of body wall sensory fiber travels - dorsal/ventral ramus - spinal nerve - dorsal root - spinal cord
DORSAL ROOT = SENSORY FIBERS ONLY
Dorsal Root Ganglion
Location of sensory cell body
Brachial Plexus
Network of ventral rami (motor + sensory) to upper extremity
Lumbosacral Plexus
Network of ventral rami (motor + sensory) to lower extremity and perineum
Myotome
Mass of muscle supplied by a single spinal nerve
Dermatome
Area of skin supplied by a single spinal nerve
ANS: Sympathetic Nervous System
Fight or flight: prep for rapid, strenuous activity
Innervates body wall (sweat glands, arrector pili muscles, peripheral blood vessells), body cavities
ANS: Parasympathetic Nervous System
Rest and digest: background maintenance activities
Innervates body cavities, head, external genitalia
ANS: 2 Neuron Pathway
Preganglionic cell body Preganglionic fiber Synapse Postganglionic cell body Postganglionic fiber
Sympathetic Preganglionic Cell Badies (location)
Lateral horn of thoracolumbar segments of spinal cord
(T1-L2/L3)
Superior segments = supply superior organs (local organization)
Parasympathetic Preganglionic Cell Bodies (location)
Brain or sacral segments of spinal cord
craniosacral
Sympathetic Postganglionic Cell Bodies (location)
Where the synapse is happening
Prevertebral (anterior to vertebral column, associated with branches of aorta)
Paravertebral (lateral to vertebral column)
Parasympathetic Postganglionic Cell Bodies (location)
Where the synapse is happening
In the head or in the walls of organs
Right on the targets
Long preganglionic, short postganglionic
Paravertebral Ganglion + Spinal Nerves
1:1
Except: cervical region (3:8)
Sympathetic Trunk
Paravertebral ganglia on each side are linked to sympathetic trunks that extend the length of vertebral column
Allow for distribution of sympathetic fibers throughout body
Tethered to ventral rami by white/gray rami communicans
White Rami Communicans
Enhance to sympathetic trunk
Gray Rami Communicans
Exit from sympathetic trunk
WINGO
White (ramus) in
Gray (ramus) out
Sympathetic Pathway: Body Wall
lateral horn (spinal cord) - ventral root - spinal nerve - ventral ramus - white ramus communicans - sympathetic trunk - synapse in paravertebral ganglion - postganglionic fiber exits sympathetic trunk via gray ramus communicans - FOLLOW ALONG VENTRAL RAMUS OR BACKTRACK TO DORSAL RAMUS - target (blood vessels, arrector pili muscles, sweat glands)
Sympathetic Pathway: Thoracic Organs
Lateral horn (spinal cord) - ventral root - spinal nerve - ventral ramus - white ramus communicans - sympathetic trunk - synapse in a paravertebral ganglion - exit sympathetic trunk through cardiac or pulmonary nerves (only sympathetic nerves) - target (heart, lungs)
Sympathetic Pathway: Abdominal Organs
Lateral horn (spinal cord) - ventral root - spinal nerve - ventral ramus - white ramus communicans - sympathetic trunk - exit sympathetic trunk WITHOUT SYNAPSING - SPLANCHNIC NERVE - synapse in prevertebral ganglion - small POSTGANGLIONIC FIBER/nerves - target (abdominal, pelvic viscera)
Visceral Sensory Pathway
Single neuron pathway
Travels towards spinal cord alongside sympathetic and parasympathetic fibers
Enters DORSAL ROOT
Referred Pain
Visceral (organ) pain being perceived as somatic (body wall) pain
Visceral sensation misinterpreted by CNS as somatic (sharp) sensation
Spinal Nerves
8 C, 12 T, 5 L, 5 S, 1 Co
C1 Spinal Nerves
Exit between skull and C1 vertebra
8 C nerves - 7 C vertebrae
Look and Label Spinal Nerve
