Spinal cord / Nerves

Gray matter

Inside butterfly shape- contains cell bodies dendrite and synapses

White matter

Outside- contains myelinated axons ascending(S) and descending(M) tracts

Gray matter

Inside butterfly shape- contains cell bodies dendrite and synapses

White matter

Outside- contains myelinated axons ascending(S) and descending(M) tracts

Central canal

Carries CSF cerebrospinal fluid

How many Spinal nerves

31 pairs

Dorsal Root

Sensory input to spinal cord

Ventral Root

Motor output from spinal cord

What is a nerve

Bundle of axons(nerve fibers) in the PNS

Endoneurium

Surrounds each axon

Perineurium

Wraps fascicles (axon bundles)

Epineurium

Outer covering of entire nerve

Dendrites

Receives signals from other neurons

Axon

Conducts impulse away from cell body

Axon hillock

Origin of action potential

Myelin sheath

Insulates axon increases conductivity

Nodes of ranvier

Gaps in myelin ion exchange occurs

Avon terminals

Release neurotransmitters at synapses

Multipolar neuron

Most common - motor neurons

Bipolar Neurons

Found in retina / olfactory epithelium

Unipolar neuron

Sensory neurons in dorsal root ganglia

Astrocytes

Support blood brain barrier

Oligodendrocytes

Myelinate CNS axons

Microglia

Immune defense

Schwann cell

Myelinate PNS axons

Satellite cells

Support neuron cell bodies in ganglia

spinal nerves contain

both sensory and motor fibres

where do spinal nerves begin

intervertibral foramen of bony vertebrea

subarachnoid space

open space next to pia

pia matter

surrounds spianl cord

epidural space

above dura