Biomechanics of NS

Question 1

True/False: The Nervous System must be able to tolerate mechanical loading, move, and physically interface with adjacent tissue.

Answer 1

True, duh

Question 2

What is the basic functional unit of the NS?

Answer 2

neuron

Question 3

What are the parts of a neuron?

Answer 3

perikaryon, dendrites, axon

Question 4

What is the perikaryon?

Answer 4

contains the neuron cell body.

is housed in the ventral horn of the SC, sympathetic trunk, and dorsal root ganglia)

Question 5

Which of the following is not true for the axon?

a. multiple fibers extending from the cell body with branches near termination
b. site of impulse conduction
c. conduction speed increases with myelination
d. conduction speed correlates with fiber diameter

Answer 5

a - it is a single fiber

d- increased conduction velocity occurs in fibers with larger diameters

Question 6

What is the dendrite?

Answer 6

branches from cell body and terminal axon, increase the number of synapses

Question 7

Where is the brain entirely housed?

Answer 7

cranium

Question 8

Which of the following is not true?

a. the SC is a continuation of the medulla oblongata from the foramen magnum
b. The SC terminates at the conus medullaris at T10
c. the SC attaches into the coccyx via filum terminale
d. nerve roots are the transitional structure from the CNS to the PNS

Answer 8

b - ends at L2

Question 9

Match the meninge to the description,

a. pia mater
b. arachnoid mater
c. dura mater

i. delicate connective tissue meshwork housing CSF
ii. delicate and continuous layer of connective tissue meshwork surrounding all elements of the CNS
iii. tightly outermost meningeal layer with high collagen content aligned in layers longitudinally
iv. connects into pia mater via arachnoid trabeculae
v. highly vascularized and innervated

Answer 9

a = ii, b = i and iv, c = iii and v

Question 10

Describe the structural hierarchy of the peripheral nervous system.

Answer 10

innermost, smallest unit is the nerve fiber housing axons within basement membrane and endoneurium.
bundle of nerve fiber = fascicle, surrounded by perineurium then epineurium.
bundle of fasciculi is a peripheral nerve trunk, enveloped by loose areolar tissue layer (mesoneurium)

Question 11

What are the supporting cells between neurons, involved in myelination?

Answer 11

neuroglia

Question 12

_ cells of the CNS, _ cells of the PNS.

Answer 12

oligodendrites, schwann

Question 13

What do the pia and arachnoid mater allow?

Answer 13

stretch and compression without kinking

Question 14

What does the dura mater provide?

Answer 14

tremendous axial loading strength and relative structural stability

Question 15

What do the peripheral connective tissues provide?

Answer 15

protection and resistance to tensile and compression forces

Question 16

Which of the following is not true for the connective tissue functions within the NS?

a. adds both tensile strength and elasticity to nervous tissue where movement is necessary
b. adds structural stability through attachments to adj structures
c. facilitates processes involved in nutrition, oxygenation, and waste removal
d. it and nervous tissue are highly innervated and nociceptive
e. influences interactions with endocrine and immune system

Answer 16

d - it is highly innervated but nervous tissue itself is not

Question 17

Which of the following is true regarding NS integration with the vascular system?

a. 45% of oxygen utilized by NS, which is 5% of body mass
b. CNS but not PNS has extensive intrinsic vascular systems
c. susceptible to mechanical compression and tensions which can alter blood flow
d. both NS and VS are highly innervated and nociceptive

Answer 17

C is true. A = 20% and 2%, B = both have them, D = nervous tissue is not

Question 18

The nervous system tissues are mechanically continuous by what means?

Answer 18

connective tissue associations

Question 19

The NS tissues are electrically continuous by what means?

Answer 19

impulse generation and transmission

Question 20

The NS tissues are chemically continuous by what means?

Answer 20

flow of neurotransmitters

Question 21

What are the NS functions?

Answer 21

1. conducts and regulate impulses via continuous electrochemical antegrade and retrograde flow
2. associate physical, psychological, and environmental inpyts
3. adapt dynamically to maintain and change its own function
4. facilitate coordinated conscious and unconscious reactions of multiple body systems

Question 22

What are the determinants of the mechanical properties of the NS?

Answer 22

continuity of nervous tissue tract;
supporting connective tissue structures;
PNS: interneural and intraneural plexus formation, and quantity of fascicles housed within nerve;
CNS: folding and twisting of axons, and nervous tissue movement in relation to neighboring bony segments

Question 23

What serves to distribute force within combinations of nerves?

Answer 23

interneural plexus in PNS

Question 24

What serves to distribute force within specific nerves?

Answer 24

intraneural plexus in PNS

Question 25

True/False: Nerve compression with greater pressure is required to affect nerve fibers in a nerve with a greater number of fascicles.

Answer 25

false - smaller number of fascicles

Question 26

What does redundancy within the tissues of the CNS allow?

Answer 26

neural structures to elongate prior to being exposed to significant tensile forces

Question 27

True/False: Normal movement of the body requires the tissues of CNS to be able to move past adj structures in which they are housed.

Answer 27

true

Question 28

What are the mechanical loads that the nervous system is exposed to?

Answer 28

compression, tension, excursion

Question 29

Which type of mechanical load can lead to alterations in fluid and blood flow within neural tissue at relatively low pressures?

Answer 29

compression

Question 30

True/False: Exposure to compression is normal if magnitude and duration is not excessive.

Answer 30

true

Question 31

What does increased tensile loading lead to?

Answer 31

decreased cross sectional area and increased intraneural pressure = decrease blood flow @ 6-8% strain, stops at 15% strain

Question 32

What occurs do to excursion loads on neural tissues?

Answer 32

“slide” relative to adj interfacing extraneural tissues

Question 33

What can mechanical loading of nervous tissue result in?

Answer 33

altered axoplasmatic flow within a nerve and altered blood supply to a nerve

Question 34

Treatment should avoid excessive loading of nervous tissue and usually focus on what?

Answer 34

relieving stresses and strains upon nerves