Spinal cord, nerves, and reflexes

CNS

brain and spinal cord, body’s primary control center

PNS

all nerves outside brin and spinal cord, communication network to CNS

Glial Cell

non-neural cells in the nervous system that provide support, protection and maintenance for neurons

Neuron

fundamental, electrically excitable units of the brain and nervous system

Afferent Neurons

Sensory nerve cells that transmit info from tissues and organs to the CNS

Efferent neurons

nerve cells that transmit motor signals away from CNS to peripheral targets like muscles and glands

Nerve Fiber

an axon is the long, threadlike extension of a neuron that transmits electrical impulses.

Endoneurium

surrounds individual nerve fibers

Perineurium

sheath surrounding nerve fiber fascicles in the PNS

Epineurium

outermost connective tissue sheath of a peripheral nerve

fascicle

small bundles of axons within the PNS

dendrite

branched extension of neurons that receive electrochemical signals from other neurons

cell body

the soma, is the core metabolic center of a neuron that houses the nucleus and organelles

nissl body

large, granular structures found in the soma and dendrites of neurons. Serve as primary site of protein synthesis

Axon

long, slender projection of a neuron that transmits electrical impulses or action potentials.

axon hillock

cone-shaped, specialized region of a neurons body that connects to the axon

axon terminal

the site of neurotransmitter release, its the button-like ending of an axon that makes contact with other neurons for a synapse

Synaptic knobs

the tiny, rounded endings of axons where neurons form synapses with other neurons, muscle cells, or glands.

synapse

a specialized junction where nerve impulses are transmitted between neurons or between a neuron and a muscle/gland cell.

Myelin Sheath

a protective layer wrapping around the axon of a neuron in the CNS and PNS

nodes of ranvier

small, periodic gaps in the myelin sheath along axons where the axonal membrane is exposed, they’re crucial for rapid signal transmission through saltatory conduction.

Schwann Cells

specialized cells in the PNS that insulate and protect nerve fibers with myelin sheaths

oligodendrocytes

specialized glial cells in the CNS that produce myelin sheaths around axons to insulate them and increase the speed of electrical signals

internodes

a segment of a myelinated axon located between two nodes of ranvier

dura mater

tough, fibrous outermost layer of the meninges protecting the brain and spinal cord

arachnoid mater

the middle, delicate, avascular meningeal layer covering the brain and spinal cord

pia mater

the innermost meningeal layer that directly covers the brain and spinal cord

epidural space

the space between the dura mater and the vertebrae

subarachnoid space

the space between the arachnoid mater and pia mater

cervical enlargement

a widened, bulbous segment of the cervical spinal cord that contains an increased amount of gray matter to accommodate the high density of neurons supplying the upper limbs.

lumbar enlargment

a widened, structurally increased section of the lumber spinal cord section, accommodating a higher volume of nerve cells to innervate the lower limbs

conus medullaris

the taper, cone-shaped terminal end of the spinal cord located near the L1-L2 vertebrae

cauda equina

a bundle of nerve roots located at the end of the spinal cord, resembling a horses tail

anterior median fissue

a deep, longitudinal grove on the ventral surface of the spinal cord.