5_Neuroanatomy and Physiology of the Spinal Cord

Question 1

The spinal cord is approximately ___ in length in males - _____ in females with a diameter of approximately _____.

Answer 1

45 cm
42 cm
1.0 - 1.5 cm

Question 2

In the adult, this means that the spinal cord ends at the vertebral level of _____.

Answer 2

L1-L2

Question 3

This disparity in length is due to a differential growth of the spinal cord versus ____________________.

Answer 3

the vertebral column

Question 4

Along the length of the cord are two observable enlargements. These occur in which two regions?

Answer 4

These occur in the cervical region and in the lumbar/sacral regions.

Question 5

Their occurrence marks the areas of the spinal cord that contain the neurons concerned with the ______________, respectfully.

Answer 5

Upper and lower extremities (brachial and lumbar plexi)

Question 6

Rostrally, the cord is continuous with the ______, caudally it tapers into a structure referred to as ___________.

Answer 6

medulla

conus medullaris

Question 7

The dorsal and ventral roots of the lower lumbar and sacral segments continue caudally to exit their appropriate ____________. Due to the differential growth of the cord versus the spine, this makes these roots very long. The collection of these long roots is the ______________.

Answer 7

intervertebral foramina

cauda equina

Question 8

The three layers of meninges:__________________________________ .

Answer 8

dura mater, arachnoid and pia cover the spinal cord.

Question 9

The dura consists only of a ____________. (the _____________ layer ended at _____________).

Answer 9

meningeal layer

the periosteal layer ended at foramen magnum

Question 10

What is the epidural space is an actual space filled with?

Answer 10

fat

Question 11

The organization of the arachnoid, acting as the limiting component for:

Answer 11

CSF containment

Question 12

The CSF gets into the subarachnoid space of the spinal canal after leaving the ___________________________.

Answer 12

foramina of Luschka and Magendie

Question 13

Since the cord ends at vertebral levels______, that leaves a large pocket of subarachnoid space below the caudal tip of the cord, known as the ________.

Answer 13

L1 - L2

lumbar cistern

Question 14

In what region are lumbar punctures (spinal taps) are routinely made? (It is safe in this region. )

Answer 14

lumbar cistern

Question 15

The pia has two components: 1) a_______ that is adhered directly to the ______, much the same as with the brain. The 2) the ___________.

Answer 15

1) pia intima
spinal cord
2) denticulate ligaments

Question 16

The denticulate ligaments are extension that _____________________ and _______________ to attach the dura.

Answer 16

extensions that PROTRUDE from the lateral sides of the cord and PIERCE THE ARACHNOID to attach to the dura.

Question 17

The purpose of the denticulate ligaments is to help _______ and ________ the cord in the vertebral canal.

Answer 17

anchor

stablize

Question 18

At the caudal end of conus medullaris, the ligament that extends to anchor the cord is called:

Answer 18

filum terminale

Question 19

The filum terminale is made up of:

Answer 19

pia, glial elements and maybe some remnants of coccygeal neuronal elements.

Question 20

AS the filum terminale extends through/and is encased with the dura to attach to the coccyx; it is termed the _________________.

Answer 20

coccygeal (sacral) ligament

Question 21

The coccygeal (sacral) ligament anchors the:

Answer 21

end of the cord in the spinal canal.

Question 22

There are ____ pairs of spinal nerves: ___ cervical, ___ thoracic, ___ lumbar, ___ sacral, and ___ coccygeal.

Answer 22

31(32)
8
12
5
5
1(2)

Question 23

During development of the cord, the segmental arrangement is obscured; with the only evidence remaining being the:

Answer 23

rootlets of the spinal nerves.

Question 24

The segmental arrangement, however, is still represented to an extent as evidenced by:

Answer 24

dermatomal maps and the multisegmental innervation of muscles

Question 25

Why is this organization clinically important in discerning the extent and/or location of a deficit? by documenting the loss of certain sensations or changes in motor activity, following damage to the central nervous system.

Answer 25

By documenting the loss of certain sensations or changes in motor activity (following damage to the central nervous system).

Question 26

The spinal cord has two main subdivisions: (as does the entire CNS): gray matter and white matter.

Answer 26

1) gray matter | 2) white matter

Question 27

Gray matter of the spinal cord is:

Answer 27

the central “butterfly” shaped area

Question 28

Gray matter consists of______________ and _________________.

Answer 28

neuron cell bodies and glial cells.

Question 29

What is white matter that is made up?

Answer 29

myelinated axons.

Question 30

The white matter contains both:

Answer 30

ascending and descending fiber tracts or pathways.

Question 31

The ascending and descending fiber tracts or pathways can be divided into three general locations named ______

Answer 31

funiculi

Question 32

Name the 3 funiculi:

Answer 32

1) dorsal (posterior) funiculus 2) lateral funiculus 3) ventral (anterior) funiculus

Question 33

Funiculus is a general term for an:

Answer 33

area of white matter

Question 34

Each funiculus is composed of a number of specific named _____, pathways or ____.

Answer 34

tracts | fasciculi

Question 35

The naming of each specific pathway can be descriptive of ________ within the transverse section of the spinal cord and may also give an indication of what __________________________.

Answer 35

location | areas within the CNS the pathway is connecting

Question 36

For example, the lateral corticospinal tract is located in the _____________ and originates in the ___________________ ending in the ___________

Answer 36

lateral funiculus cortex of the cerebral hemisphere spinal cord.

Question 37

The gray matter is composed of what 3 structures:

Answer 37

1) nerve cell bodies 2) their dendritic processes 3) glial cells.

Question 38

True or False: the organization within the gray matter of the spinal cord was not setup developmentally.

Answer 38

False: There is an organization within the gray matter of the spinal cord that was set up developmentally.

Question 39

The alar plate is ______ located and is concerned with ___________ sensory information from the ________.

Answer 39

dorsally afferent periphery

Question 40

The basal plate is ________ located and is concerned with _______ components of the cord.

Answer 40

ventrally | motor

Question 41

The butterfly shaped gray area is then divided into a:

Answer 41

dorsal horn (sensory) and a ventral horn (motor).

Question 42

There is a lateral horn (intermediolateral cell column) present from spinal cord segment ____.

Answer 42

T1-L2

Question 43

The lateral horn is the location of the _________________________, a component of the Autonomic Nervous System (ANS).

Answer 43

preganglionic sympathetic neurons

Question 44

The sacral segments (S1 -S3) also have a lateral horn that contains the ___________________________ for the lower parts of the body, the other part of the ANS

Answer 44

preganglionic PARAsympathetic neurons

Question 45

Where are other parasympathetic neurons located?

Answer 45

cranial nerves

Question 46

The gray matter has been divided into various nuclei or divisions as a result of:

Answer 46

cellular (cytoarchitecture) and connectional studies.

Question 47

One terminology uses Roman Numerals referred to as ________________. Another system names ______________________.

Answer 47

Lamina of Rexed | regions of the gray matter

Question 48

Name 6 regions of the gray matter:

Answer 48

1) Lissauer’s Tract (dorsolateral tract of Lissauer) 2) substantia gelatinosa 3) nucleus proprius 4) Dorsal nucleus of Clarke 5) intermediolateral cell column or lateral horn 6) ventral horn; location of the lower motor neurons

Question 49

The dorsal horn contains which two regions of gray matter?

Answer 49

substantia gelatinosa and nucleus proprius (among others)

Question 50

The substantia gelatinosa is in lamina _____.

Answer 50

II

Question 51

The nucleus proprius is in lamina _____.

Answer 51

III and IV

Question 52

the dorsal nucleus of Clarke is located in lamina _____ and segmental levels __________.

Answer 52

VII | T2-T12

Question 53

The intermediolateral cell column or lateral horn is in lamina ____ (in part) and segmental levels ______________________________.

Answer 53

IX | C8/T1-L2 and S1-3

Question 54

the ventral horn is locate in part in lamina ___

Answer 54

IX

Question 55

There is a ___________ organization of the fibers that enter the cord via the dorsal root.

Answer 55

medial to lateral

Question 56

When viewed from a transverse (horizontal) perspective, the more medially situated fibers are the __________________________________.

Answer 56

large diameter, heavily myelinated (Ia/b, A-α, ΙΙ) fibers

Question 57

The more laterally placed fibers are the __________________________ .

Answer 57

small diameter, non-myelinated C fibers.

Question 58

Fibers of intermediate caliber that are _____________________________.

Answer 58

finely myelinated lie intermediate in this organization (A-delta; A-δ).

Question 59

Which fiber types are the fibers that enter the cord at Lissauers tract.

Answer 59

A-delta

Question 60

The ventral horn contains the _______________ that will leave the spinal cord and____________. These are the ___________.

Answer 60

cell bodies with axons innervate muscles lower motor neurons

Question 61

What is the "Final Common Pathway” for information that is needed to make a muscle do its thing.

Answer 61

synapsing from ventral horn

Question 62

There are two types of lower motor neurons (LMN) within the ventral horn:

Answer 62

1) α motor neurons and | 2) γ-motor neurons

Question 63

The cell bodies of these neurons are arranged within the ventral horn so that those situated most medially are concerned with :

Answer 63

axial musculature, i.e. trunk, neck, etc | *This cell column extends throughout the entire length of the cord

Question 64

The LMNs situated more laterally innervate:

Answer 64

The muscles of the extremities.

Question 65

Where would the largest ventral horns be located?

Answer 65

at cervical and lumbar regions, associated with brachial and lumbar plexuses ????

Question 66

LMNs situated posteriorly in the ventral horn are concerned with__________________, and those located anteriorly are concerned with ________________.

Answer 66

muscles of flexion | muscles of extension

Question 67

The merging of the dorsal and ventral roots away from the spinal cord forms the _________.

Answer 67

spinal nerve

Question 68

Prior to them merging, the dorsal root is _______ sensory and the ventral root is ______ motor.

Answer 68

entirely | entirely

Question 69

Once they have combined, the spinal nerve is a _____ nerve, i.e., has both motor and sensory components.

Answer 69

mixed **This spinal nerve is a component of the peripheral nervous system.

Question 70

After the dorsal and ventral roots have combined, each spinal nerve then branches into a number of branches to :

Answer 70

reach its specific dermatomal segment or muscle of innervation

Question 71

Associated with the spinal nerves at spinal cord levels T1-L2 is a series of ___________________.

Answer 71

autonomic ganglia

Question 72

These autonomic ganglia are the location of the ___________________________________________.

Answer 72

postganglionic cell bodies for the sympathetic nervous system.

Question 73

The preganglionic cell bodies (of the autonomic ganglia?) are located in the :

Answer 73

lateral horn in the spinal cord (intermediolateral cell column).

Question 74

Reflexes are _____, ________________ responses to an adequate (appropriate) stimulus.

Answer 74

specific | stereotyped motor

Question 75

Reflexes require a series of structures consisting of a minimum of what 4 components:

Answer 75

1) receptor 2) afferent limb 3) efferent limb 4) effector organ (**complex reflexes may contain more connections in the CNS):

Question 76

Examples of a receptor:

Answer 76

muscle spindles, golgi tendon organs, encapsulated and free nerve endings.

Question 77

An afferent limb carries the impulse (stimulus) into the:

Answer 77

CNS; i.e., dorsal root fibers.

Question 78

An efferent limb carries the impulse for the response:

Answer 78

out of the CNS; i.e., lower motor neuron (α-motor neuron).

Question 79

lower motor neurons are:

Answer 79

a-motor neurons

Question 80

An example of an effector organ would be:

Answer 80

skeletal muscle, glands.

Question 81

Stretch Reflex or Deep Tendon Reflex (DTR) used to be classified:

Answer 81

Myotatic or monosynaptic

Question 82

The patellar ligament or knee jerk is an example of what?

Answer 82

stretch reflex

Question 83

This stetch reflex demonstrates the principle of:

Answer 83

Autogenic Facilitation

Question 84

Autogenic Facilitation and can be thought to include a small amount of __________________.

Answer 84

Reciprocal Inhibition

Question 85

Any external force stretching the muscle excites the Type Ia axons, which excite the motor neuron pool, which oppose the external force by activating the muscle, this process is termed:

Answer 85

autogenic facilitation

Question 86

Whenever antagonist muscles are inhibited during the activation of agonist muscles, the process is called:

Answer 86

reciprocal inhibiton

Question 87

The Golgi Tendon Organ (GTO), is sensitive to tension when the associated muscle is _______.

Answer 87

contracting

Question 88

At a certain point of increased tension, during the GTO, the stimulus generates an inhibitory influence to the α motor neurons that are driving the contracting muscle, demonstrating the principle of:

Answer 88

Autogenic Inhibition

Question 89

During the GTO, autogenic inhibition, the muscle now can relax which ___________.

Answer 89

releases the tension

Question 90

Through the interneuronal pool, the antagonistic muscle can be activated to facilitate the release of tension, which is a process called:

Answer 90

Reciprocal Facilitation

Question 91

What reflex if more complex compared to the stretch reflex and GTO?

Answer 91

Flexor Withdrawal Reflex and Crossed Extension Reflex.

Question 92

Why are the Flexor Withdrawal Reflex and Crossed Extension Reflexes more complex?

Answer 92

more than just two neurons are involved.

Question 93

When more than just 2 neurons are involved, what must happen?

Answer 93

Reciprocal inhibition of antagonist or opposing muscle masses must occur.

Question 94

Reciprocal inhibition = ___________ muscle

Answer 94

antagonistic

Question 95

Recurrent inhibition = (Renshaw cells) =

Answer 95

same muscle and synergists

Question 96

Non- reciprocal inhibition =

Answer 96

inhibits agonists, synergists and antagonists (coordination of various movements)

Question 97

Segmental loss involves the structures that are:

Answer 97

present at the specific segmental level.

Question 98

Segmental loss includes the gray matter areas of the cord and to some extent the _________________________ that are bringing in sensory information and/or sending out motor information.

Answer 98

dorsal and ventral root components

Question 99

What segmental loss generally does not refer to is the additional:

Answer 99

involvement of ascending or descending white matter pathways that are also involved.

Question 100

In the real world, segmental losses will most likely include

Answer 100

some involvement of the white matter.