Nervous System Flashcards
Organs of the central nervous system
brain and spinal cord
Main functions of the nervous system
collect, process, evaluate and respond to information
Sensory vs. motor nervous system
sensory: input, PNS (receptors) to CNS,
motor: output, CNS to PNS (muscles or glands)
Somatic vs. visceral sensory systems
somatic: voluntary; senses from skin, fascia, joints, and skeletal muscle; sense touch, temperature, pain, proprioception, pressure, vibration, special senses
visceral: involuntary; senses from blood vessels and organs; sense temperature and stretch
Somatic vs. autonomic motor systems
somatic: voluntary; innervates skeletal muscle; motor fibers are one cell
autonomic: involuntary; innervates cardiac muscle, smooth muscle, glands; two divisions-sympathetic and parasympathetic; motor fibers are two cells
Three characteristics of all neurons
extreme longevity, nonmitotic, high metabolic rate
Nissl bodies
granular bodies in neurons made of rough ER and free ribosomes for protein synthesis
Five common features of neurons
soma/cell body, dendrites, axon hillock, axon, terminal boutons
Most sensory neurons are this structural “polarity”
[pseudo]unipolar
Most uncommon neuron “polarity”, found in olfactory epithelium and the retina
bipolar - one axon and one dendrite
Afferent neurons
sensory neurons going to or “arriving” at CNS, mostly unipolar with cell bodies in dorsal root ganglia
Efferent neurons
motor neurons going away from CNS to muscles/glands; all multipolar with cell bodies mostly in spinal cord
99% of all neurons
interneurons
Glioma
tumor of glial cells that have lost their ability to control cell division
Astrocytes
in CNS
most abundant glial cells that support neurons by filtering nutrients and waste from capillaries
form blood-brain barrier
Ependymal cells
in CNS
epithelial cells with no BM
line ventricles of brain and central canal of spinal cord
have cilia to circulate CSF and microvilli to help produce CSF
Microglial cells
in CNS
normally small, but become phagocytic when activated to defend against foreign invaders
Oligodendrocytes
in CNS
myelinate axons
each can wrap around multiple axons
Neurolemmocytes/Schwann cells
in PNS
myelinated axons
Satellite cells
in PNS
flat cells around sensory cell bodies in dorsal root ganglia to protect, provide structure, regulate nutrients
Purpose of myelin
high lipid content insulates axon allowing action potential to conduct faster (AP doesn’t have to travel along entire membrane but jumps from gap in sheath to next gap
Gaps in the myelin sheat
Nodes of Ranvier
Three CT wrappings of nerves
endoneurium: around single axon/nerve fiber
perineurium: around bundle of axons/fascicles
epineurium: around bundle of fascicles and blood vessels/nerve
Gray matter
collection of nerve cell bodies, dendrites, glial cells and unmyelinated axons (mainly cell bodies and interneurons)
called ganglia in PNS and nuclei in CNS
White matter
collection of myelinated axons
called nerve in PNS and tract in CNS
Three types of synapses
axodendritic: axon terminal bouton to dendrite (most common)
axosomatic: axon terminal bouton to cell body of neuron
axoaxonic: axon terminal bouton to terminal bouton of another axon (least common)
Results of sympathetic nervous system activation
"fight or flight" pupils dilate heart rate, blood pressure increase blood to skeletal muscle thoracic/lumbar
Results of parasympathetic nervous system activation
"rest and digest" pupils constrict heart rate and blood pressure decrease blood to digestive organs cranial/sacral
Three locations of sympathetic ganglia
paravertebral chain: short pre- and long postganglionic fibers
cervical
collateral/prevertebral
Main parasympathetic nerves
cranial nerves III, VII, IX, X
(ciliary, pterygopalatine, submandibular, otic ganglia)
pelvic splanchnic nerves
Synapses in paravertebral chain of ganglia lead here
spinal nerves to skin: sweat glands, blood vessels, and erector pili
Synapses in cervical ganglia lead to here
head, heart, and lungs
Nerves that lead to collateral ganglia
splanchnic nerves (preganglionic fibers)
Synapses in collateral ganglia lead to here
abdominal pelvic organs
reproductive organs-greater, lesser, and least thoracic splanchnic nerves and sacral splanchnic nerves
Which vertebrae spinal nerves C1-C7 are named after
the vertebra directly below them
Which vertebra spinal nerve C8 is above
T1
Which vertebrae spinal nerves T1-Co1 (all but C1-C8) are named after
the vertebra directly above them
The dorsal ramus innervates these muscles
deep back and intrinsic back muscles
skin of back
Rami communicantes come off these rami
ventral rami
Spinal nerves that have white rami
T1-L2
Levels of spinal cord with a lateral horn in addition to the ventral and dorsal horns
T1-L2
Spinal cord extends from where to where
brain to about L2
The tapering end of the spinal cord
conus medullaris
Axons projecting inferiorly from end of spinal cord
cauda equina
Anchors conus medullar is to coccyx
filum terminale
What filum terminale is made from
pia mater
Largest part of spinal cord
cervical part
Part of spinal cord with most white matter to gray matter ratio
cervical part
Part of spinal cord with most gray matter to white matter ratio
sacral part
Second largest part of spinal cord
lumbar part (heavier in gray matter than cervical)
Number of pairs of spinal nerves
31
C1-C8, T1-T12, L1-L5, S1-S5, Co1
Order of spinal meninges and spaces
vertebra, epidural space, dura mater, subdural space, arachnoid mater, subarachnoid space, pia mater
Space around spinal cord filled with CSF
subarachnoid space (spinal tap goes here)
The grooves on either side of exterior spinal cord
dorsal median sulcus and ventral median fissure
Central canal of spinal cord
continuous with brain ventricles and fill with CSF
Dorsal root ganglia
cell bodies of sensory neurons (pseudo unipolar) and satellite cells
Ventral horns
cell bodies of somatic motor neurons that carry efferent info and innervate skeletal muscle
Dorsal horns
axons of sensory neurons and cell bodies of interneurons that carry afferent info
(cell bodies of sensory neurons are in dorsal root ganglia)
Lateral horns
(only in T1-L2)
cell bodies of autonomic motor neurons that innervate cardiac muscle, smooth muscle, and glands
Gray commissure
unmyelinated axons that surround central canal and connects left and right side of gray matter (horns) in spinal cord
How white matter is organized
posterior, anterior and lateral funiculi each with ascending and descending tracts and commissural tracts connecting left to right
Levels of spinal cord with nerve cell bodies for parasympathetic nerves
S2-S4
Levels of spinal cord with neither sympathetic nor parasympathetic coming out
L3-S1
Cervical plexus
C1-C4
phrenic nerve
Brachial plexus
C5-T1
innervates shoulder and arm
Lumbar Plexus
L1-L4
innervates anterior and medial thigh
ventral rami split into anterior and posterior rami
The ramus that branches into plexi
ventral ramus
The spinal nerves that don’t form plexi and nerves they serve
T2-T12
thoracic spinal nerves (intercostals, subcostal)
Nerve lateral to psoas major muscle that passes under inguinal ligament
femoral nerve
Nerve medial to psoas major muscle
obturator nerve
Femoral triangle borders
adductor longus, inguinal ligament, sartorius
Sacral plexus
L4-S4
innervates gluteal region, posterior thigh, and leg
sciatic nerve (tibial and common fibular), pudendal nerve, superior and inferior gluteal nerves
Sciatic nerve
largest nerve of body, contains tibial and common fibular nerve
Branches of brachial plexus
5 ventral rami, 3 trunks (superior, middle, inferior), 6 divisions (3 anterior and 3 posterior), 3 cords (lateral, medial and posterior), 5 branches
Names of the five branches of brachial plexus
posterior: axillary and radial
anterior: ulnar, median, musculocutaneous
