ANPS - Spinal Cord and Spinal Nerves

Peripheral Nerve

a bundle of nerves traveling between the CNS and targets in the periphery; connects skeletal muscle to the CNS

Fascicle

a bundle of axons held together by perineurium

Endoneurium

connective tissue around a singular axon

Perineurium

connective tissue around a group of axons

Epineurium

connective tissue around the whole nerve

Sensory neurons

pseudounipolar neuron, collect information to send to the CNS; receive a singular piece of information that does not pass through the cell body

Motor neurons

multipolar shaped neuron, the cell body and dendrites are in the CNS, convey information from CNS to peripheral location

Somatic sensory neurons

collect information from muscles and receptors about muscle activity and convey it to the CNS

somatic motor neurons

send commands telling the skeletal muscle cells to contract; they release acetylcholine at the neuromuscular junction on individual cells

Pseudounipolar shape

cell body with no dendrites, singular process extends from the peripheral to the central nervous system (sensory neuron shape)

multipolar shape

dendrites branch off directly from the cell body with one longer process that acts as the axon

Spinal nerve

nerves that are attached to the spinal cord; connect spinal cord to the periphery, innervate limbs and trunk, has sensory and motor axons

Cranial nerve

nerves that are attached to the brain

Dorsal roots

where the axons of the sensory neurons enter the spinal cord; carries information into the spinal cord

Ventral roots

where axons of motor neurons leave the spinal cord; carries information away from the spinal cord

Dorsal root ganglion

groups of sensory neuron cell bodies and lies just outside the vertebral canal

White matter

lighter peripheral area of the spinal cord; color due to myelinated axons found in this tissue

Gray matter

darker central area of the spinal cord; color is due to very little myelinated axons found in this tissue (dendrites, cell body, supporting cells, etc.)

Sensory tract

axons that carry information up to the brain

motor tracts

axons that carry information down from the brain to spinal cord and motor neurons

Dorsal horns

grey matter found in the dorsal (back) part of the spinal cord; carries sensory information and processes it

ventral horns

grey matter found in the ventral (front) part of the spinal cord, houses motor neurons and carries commands to these motor neurons

Intermediate zone

the zone between the dorsal and ventral horns

Ramus

branch

Dorsal rami

runs dorsally and branches to innervate a small band of skin on the back and postural muscles of the dorsal spine

Ventral rami

branches to innervate skin, joints, muscles, on the lateral and anterior (front) side including all limbs; 4 times bigger in diameter than dorsal ramus

Meninges

3 layers of supportive tissue that protects the CNS

Pia mater

supported tissue adhered to the surface of the brain and spinal cord, cannot be peeled off!

arachnoid mater

very thin, transparent, delicate tissue surrounding pia mater

dura mater

tough collagen (CT) rich tissue around the arachnoid tissue; provides the most protection for CNS

Subarachnoid space

space between pia and arachnoid filled with cerebrospinal fluid

Spinal segment

the repeating units of an adult spinal cord, each segment contains a pair of spinal nerves, 31 total segments

Dermatome

the band of skin that is innervated by a pair of spinal nerves

Myotome

the skeletal muscle cells that is innervated by a a pair of spinal nerves

Filum terminale

a strand of pia matter that extends from the conus medullaris to the bottom of the sacrum helping to anchor the spinal cord

Conus medullaris

where the spinal cord tapers to a point at its end

Cauda equina

the mass of stringy nerves that leave the bottom of the spinal cord creating the lower spinal cord

Nerve Plexus

ventral rami of spinal nerves that merge into a bundle with adjacent ventral rami

Cervical Plexus

ventral rami from C1-C4, innervates skin and anterior spine muscles of neck

Phrenetic Nerve

part of the cervical plexus; C3-C5 levels keep the diaphragm alive

Brachial Plexus

tangle of nerves from C5-T1; innervate all muscles in the upper limbs; 5 major nerves of the limbs

Axillary nerve

2 muscles in shoulder

Musculocutaneous nerve

anterior arm muscles

Median nerve

most of anterior forearm and thumb muscles

Ulnar nerve

ulnar side of anterior forearm and most muscles in the hand

Radial nerve

all muscles in posterior arm and forearm

Lumbar plexus

L1-L4 rami; innervate skin and muscles of the anterior and medial thigh and skin of medial leg; 2 major nerves in lower limb

Femoral nerve

anterior thigh

Obturator nerve

medial thigh

Sacral Plexus

L4-S3 rami; innervate skin and muscles of gluteal region, posterior thigh, leg and foot; 2 major nerves of the leg

Gluteal nerves

gluteal muscles

Sciatic nerve

remainder leg muscles

Tibial nerves

branch of sciatic nerve; posterior thigh, leg, foot

Common fibular nerve

branch of sciatic nerve; lateral and anterior leg muscles