Peripheral Nervous System and Spinal Cord (Part 1)

brain and spinal cord

Central Nervous System (CNS)

nervous structures outside of brain and spinal cord (e.g. nerves and ganglia)

Peripheral Nervous System (PNS)

specific type of communication between the CNS and structures in the body in the form of electrical impulses and chemical or electrical signals that travel through the PNS

innervation

Afferent innervation that reaches conscious awareness

sensory innervation

Efferent innervation that causes a structure to do something (e.g. causes muscles to contract, glands to secrete)

Motor innervation

nerve cells; transmit innervation in for of electrical impulses and chemical or electrical signals

Neurons

sensory

what type of nerve cell is this?

Peripheral Process (carried impulse to cell body)

Assuming the direction of impulse is left to right, what is 1

cell body

Assuming the direction of impulse is left to right, what is 2

central process (carries impulse from cell body)

Assuming the direction of impulse is left to right, what is 3

motor

what type of neuron is this?

Axon (carried impulse from cell body)

assuming the direction of impulse is right to left, what is 1

cell body

assuming the direction of impulse is right to left, what is 2

dendrites (carries impulse to cell body)

Assuming the direction of impulse is right to left, what is 3

location where one neuron transmits its impulse to another cell

synapse

sheath surrounding long fibers of neurons that speeds up conduction of impulses (most neurons in the PNS have this)

myelin sheath

a fiber that has a myelin sheath

myelinated fiber

a collection of neuronal fibers surrounded by connective tissue in the PNS

nerve

a collection of neuronal cell bodies surrounded by connective tissue in the PNS

Ganglion (plural: ganglia)

parts of CNS that are mainly comprised of myelinated fibers

white matter

parts of CNS that are mainly comprised of neuronal cell bodies and unmyelinated fibers

gray matter

structures comprised of somatic tissue and associated fascia

somatic structures

somatic tissue

skeletal muscle, bone, skin, and other associated connective tissues are ____________ tissue

structures comprised of visceral tissue and associated fascia (includes internal organs)

visceral structures

visceral tissue

smooth and cardiac muscle and glands are __________ tissue

skin, superficial fascia, deep fascia, skeletal muscle, bone

somatic structures that form the body wall

internal organs and associated structures

visceral structures in the body cavity

glands (e.g. sweat), arrector pili muscles, and smooth muscle in blood vessels

visceral structures in the body wall

visceral sensory (visceral pain), somatic sensory, sympathetic, parasympathetic, and somatic motor

the 5 types of innervation

carry somatic innervation (among other types) for somatic structures if body wall (below the head)

spinal nerves

segment of spinal cord that gives rise to a single pair of spinal nerves

spinal cord segment/ level

31

there are _____ spinal nerve pairs

C1-C8

cervical nerves (quantity/name)

T1-T12

thoracic nerve pairs (quantity/name)

L1-L5

lumbar nerve pairs (quantity/name)

S1-S5

sacral nerve pairs (quantity/name)

Co1

Coccygeal nerve pair(s) (quantity/name)

dorsal horn

what is 1

ventral horn

what is 2

dorsal root

what is 3

ventral root

what is 4

Dorsal Root Ganglion (DRG)

what is 5

spinal nerve

what is 6

dorsal ramus

what is 7

ventral ramus

what is 8

a strip of skin that receives somatic sensory innervation from a particular spinal cord segment; names according to spinal cord segment

Dermatome (adult)

paired sequential blocks of embryonic tissue on either side (left and right) of the developing spinal cord

somites

31

there are _____ pairs of somites

part of the somite that will contribute to development of skin and skeletal muscle of body wall

dermomyotome

contributes to skin (dermis)

dermatome (embryonic)

develops into skeletal muscle

myotome (embryonic)

epaxial division

the dorsal portion each embryonic dermatome/myotome set separates into is called the

hypaxial division

the ventral portion each embryonic dermatome/myotome set separates into is called the

dorsal ramus; ventral ramus

each spinal nerve corresponding to the dermatome/myotome sets separates into a dorsal branch (aka the ____________) and a ventral branch (aka the ________________)

epaxial division

the dorsal ramus will innervate the structures developed from the ________________ division

hypaxial division

the ventral ramus will innervate the structures developed from the ______________ division

Dermatome: skin along central back

Myotome: intrinsic back muscles (ONLY)

The epaxial dermatome and myotome derivatives are....

dorsal ramus

structures derived from the epaxial division are innervated by the...

Dermatome: skin of body wall (INcluding limbs, EXcluding skin of central back)

Myotome: Skeletal mucles (INcluding limbs, EXcluding intrinsic back muscles)

The hypaxial dermatome and myotome derivatives are....

ventral ramus

structures derived from the hypaxial division are innervated by the...

True

True of False: a single muscle derived from multiple myotomes can be innervated by several myotomes corresponding spinal nerve

the origin of sensory innervation; specialized sensory structure that sends an impulse in response to a stimulus (Can originate in both epaxial and hypaxial derivatives with the goal destination being the CNS)

Receptor (Somatic Sensory)

the destination of motor innervation; the structure that is being innervated (can target both epaxial and hypaxial muscles- originating from the CNS)

Target (Somatic Motor)

ventral horn (cell body) -> [ventral root -> spinal nerve -> ventral ramus](Axon) -> hypaxial muscles (target)

Somatic motor pathway to hypaxial muscles

ventral horn (cell body) -> [ventral root -> spinal nerve -> dorsal ramus](Axon) -> epaxial muscles (target)

somatic motor pathway to epaxial muscles

hypaxial structures (receptors) -> [ventral ramus -> spinal nerve -> dorsal root](peripheral process) -> DRG (cell body) -> dorsal root -> dorsal horn

somatic sensory pathway from hypaxial structures

epaxial structures (receptors) -> [dorsal ramus -> spinal nerve -> dorsal root](peripheral process) -> DRG (cell body) -> dorsal root -> dorsal horn

somatic sensory pathway from epaxial structures

one neuron pathway

somatic innervation is a _______ neuron pathway

ventral horn

somatic motor cell bodies are located in the

dorsal root ganglion

somatic sensory cell bodies are located in the

localized

Somatic sensory pain in the diaphragm is.... (Exception to typical somatic sensory)