CNS/ANS

Question 1

Internal structure of spinal cord

Answer 1

1) gray matter - H-shaped region of cell bodies, dendrites, proximal axons
2) white matter - axons pass longitudinally along spinal cord. Myelin, glial cells surrounding many axons, “whitens” the tissue

Question 2

Peripheral nerves

Answer 2

1) rootlets extend out from dorsal and ventral horns and converge into the roots
2) dorsal and ventral roots exit vertebral column and unit to form the spinal nerve
3) spinal nerve splits into RAMI (dorsal ramus innervates deep back muscles and overlying skin, ventral ramus innervates remaining muscles, skin, etc)

Question 3

Dorsal root ganglion

Answer 3

is formed by the cell bodies of sensory neurons

Question 4

Chain of sympathetic ganglia

Answer 4

runs perpendicular to peripheral nerves (connected to peripheral nerves by communicating rami)

Question 5

Sensory neurons

Answer 5

convey info from periphery to CNS (enters dorsal root and horn, cell body in dorsal root ganglion)

Question 6

Motor neurons

Answer 6

convey info from CNS to periphery (cell body in ventral horn, axons exit ventral root to innervate skeletal muscles

Question 7

Sympathetic nuerons

Answer 7

are found in essentially all nerves. Preganglionic cell body in intermediolateral column (IMC); projects axon to sympathetic ganglion. Postganglionic cell bodies form the sympathetic ganglia; they project their axons to the periphery

Question 8

Spinal cord reflexes

Answer 8

1) myotactic reflex (muscle stretch reflex- deep tendon reflexes doctors test with reflex hammers
2) withdrawl reflex (AKA pain reflex - neuronal pathway utilizes an interneuron pool to transmit from sensory to motor neurons
3) crossed extensor reflex (almost immediately after a pain reflex causes flexion of a limb, the opposite limb begins to extend
4) reciprocal inhibition (when a muscle is excited there is often a simultaneous inhibition of the antagonist muscle group

Question 9

All neurons in the PNS are surrounded by

Answer 9

Glia (schwann cells)

Question 10

Connective tissue around nerves

Answer 10

1) epineurium (around whole nerve)
2) perineurium (around fascicles of nerve fibers
3) endoneurium (around individual axons

Question 11

nervi nervorum

Answer 11

local nerves to CT of nerves

Question 12

vasa nervorum

Answer 12

local blood vessels to nerves

Question 13

propioception

Answer 13

the sense of the relative position of one’s own body. Information gathered by Golgi Tendon Organs, Muscle Spindle Fibers, cutaneous sensory nerves, the eyes, and the inner ear. This sensory information is processed by the cerebrum and cerebellum

Question 14

neural disease can be due to damage to either axons or glial cells

Answer 14

causes include: diabetes, kidney failure, chronic alcoholism, nutritional deficiency, autoimmune disease, trauma

Question 15

axonal degeneration

Answer 15

symptoms progress from the hands and feet proximally because injury begins in the distal parts of axons. Often occurs after injury to axon, but may be from chemo medication or inherited neurodegenerative diseases

Question 16

demyelination

Answer 16

degeneration of glia and the unraveling of myelin sheaths around axons. Guillain-Barre: demyelination of mostly motor fibers by auto immune response to infection, surgery, or immunization (contrast with MS, a demyelinating disease in the CNS

Question 17

first degree injury

Answer 17

due to temporary compression of nerves causes numbness - painful tingling in recovery period, slow conduction pain neurons are the first to recover from anoxia.

Question 18

regeneration of neuron in ANS

Answer 18

proximal end of axon regenerates new axon (sprouting). Basal lamina tunnels guide axons and permit proliferation of glial cells, minority of axon terminals find the correct way back; the rest degenerate. Target structures use trophic factors to re-establish connections. Regrowth rate ~ 1mm/da

Question 19

regeneration of neuron in CNS

Answer 19

very localized in brain. Oligodendrocytes do not have basal lamina to form tunnels to axonal regrowth

Question 20

brachial plexus

Answer 20

nerves contain axons of sensory, motor and autonomic neurons. Single nerve to a limb structure contains axons from two or three contiguous levels of the spinal cord. This arrangement develops prenatally and independently of any influence from the spinal cord

Question 21

Randy Travis Drinks Cold Beer

Answer 21

Randy = Roots
Travis = Trunks
Drinks = Divisions
Cold = Cords
Beer = Branches

Question 22

nerve distribution

Answer 22

area of skin innervated by one peripheral nerve, eg. lateral cutaneous nerve to forearm

Question 23

dermatome

Answer 23

area of skin innervated by one spinal segment

Question 24

myotome

Answer 24

area of muscle innervated by one spinal segment. Usually 2-3 segments per muscle. Often evaluated by strength testing

Question 25

posterior triangle

Answer 25

space between trapezius, clavicle and sternocleidomastoid. Brachial plexus and axillary artery pass between anterior and middle scalene muscles

Question 26

axilla: “armpit”

Answer 26

triangular space between ant. and post. axillary folds (pec major, latissimus, humerus, and rib cage)