Session 5: Neuroanatomy and Physiology of the Spinal Cord Flashcards Preview

DPT704: Neuroscience > Session 5: Neuroanatomy and Physiology of the Spinal Cord > Flashcards

Flashcards in Session 5: Neuroanatomy and Physiology of the Spinal Cord Deck (108)
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1
Q

How long is the spinal cord in males? In females?

A

Males: 45 cm
Females: 42 cm

2
Q

What is the approximate diameter of the spinal cord?

A

1.0-1.5 cm

3
Q

At what vertebral level does the spinal cord end?

A

L1-L2

4
Q

The disparity in length of the spinal cord is due to what?

A

The differential growth of the spinal cord versus the vertebral column.

5
Q

There are two observable enlargements along the length of the spinal cord. Where are they?

A

one in the cervical region, one in the lumbar/sacral regions.

6
Q

What are the observable enlargements of the spinal cord?

A

Their occurrence marks the ares of the spinal cord that contain the neurons concerned with the upper and lower extremities.

7
Q

Rostrally, the cord is continuous with what?

A

The medulla

8
Q

Caudally, the spinal cord tapers into what?

A

The conus medullaris.

9
Q

What happens to the dorsal and ventral roots after the conus medullaris?

A

They continue caudally through the lower lumbar and sacral segments, exiting their appropriate intervertebral foramina.

10
Q

What is the cauda equina?

A

The collection of long dorsal and ventral roots of the lower lumbar and sacral segements.

11
Q

What are the roots in the cauda equina long?

A

Due to the differential growth of the cord versus the spine.

12
Q

What 3 layers cover the spinal cord?

A

3 layers of meninges:

  1. Dura mater
  2. Arachnoid mater
  3. pia mater.
13
Q

How is the dura covering the spinal cord different than the dura covering the brain? Where does it make this transition?

A

Spinal cord dura: only a meningeal layer.

Periosteal layer ends at the foramen magnum.

14
Q

What fills the epidural space in the spinal cord?

A

Fat

15
Q

True or false. The arachnoid is arranged differently in the spinal cord.

A

False.

The organization of the arachnoid is much the same, acting as the limiting component for CSF containment.

16
Q

How does CSF enter the subarachnoid space of the spinal canal?

A

From the foramina of luschka and Magendie

17
Q

What is the lumbar cistern?

A

A large pocket of subarachnoid space below the caudal tip of the cord. Exists because the cord ends at vertebral levels L1-L2.

18
Q

What procedure is routinely done at the lumbar cistern.

A

Lumbar punctures (spinal taps). It is safe to make punctures in this region.

19
Q

What are the two layers of the pia?

A

pia intima

layer that forms detniculate ligaments

20
Q

What are denticulate ligaments?

A

The extensions that protrude from the lateral sides of the cord and pierce the arachnoid to attach to the dura.

21
Q

What is the purpose of denticulate ligaments?

A

Help anchor and stabilize the cord in the vertebral canal.

22
Q

What is located at the caudal end of conus medullaris?

A

The filum terminale ligament

23
Q

What makes up the filum terminale?

A

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

24
Q

What is the coccygeal (sacral) ligament a continuation of?

A

The filum terminale

25
Q

Where does the filum terminale become the coccygeal ligament?

A

Where the ligament extends through/and is encased with teh dura to attach to the coccyx.

26
Q

What is the purpose fo the coccygeal ligament?

A

Anchors the end of the cord in the spinal canal.

27
Q

How does the spinal cord develop?

A

Segmentally

28
Q

What structures develop segmentally besides the spinal cord?

A

Somites, dermatomes, myotomes and sclerotomes

29
Q

How many pairs of spinal nerves are there? How many per region of the spine? (cervical, thoracic, lumbar, sacral, coccygeal)

A
31(32) pairs
8 cervical
12 thoracic
5 lumbar
5 sacral
1(2) coccygeal
30
Q

During spinal cord development is the segmental arrangement visible?

A

No- obscured.

31
Q

What evidence is there of spinal cord segmental arrangement?

A

The rootlets of the spinal nerves

32
Q

What two places is the segmental arrangement of the spinal cord represented?

A
  1. Dermatomal maps

2. multisegmental innervation of muscles.

33
Q

What is the clinical significance of spinal cord segmentation?

A

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.

34
Q

What are the two main subdivisions of the spinal cord?

A

gray matter

white matter

35
Q

What is the central butterfly shaped area of the spinal cord?

A

Gray matter

36
Q

What makes up the gray matter of the spinal cord?

A

neuron cell bodies and their dendritic processes and glial cells

37
Q

What surrounds the gray matter in the spinal cord?

A

White matter

38
Q

What makes up the white matter of the spinal cord?

A

Myelinated axons

39
Q

What is contained in the white matter of spinal cord?

A

ascending and descending fiber tracts or pathways

40
Q

What are funiculi? How many general locations are they divided into?

A

A bundle of nerve tracts that make up the white matter of the spinal cord.

Can be divided into 3 general locations.

41
Q

What are the 3 funiculi of the spinal cord?

A
  1. Dorsal (posterior) funiculus
  2. Lateral funiculus
  3. Ventral (anterior) funiculus
42
Q

What are the specific named tracts or pathways that make up each funiculus called?

A

Fasciculi

43
Q

How are specific pathways named? Give an example.

A
  • Descriptive of location within the transverse section of the spinal cord
  • may also give an indication of what areas within the CNS the pathway is connecting.

Example: Lateral corticospinal tract. 1)located in the lateral funiculus 2)originates in the cortex of the cerebral hemisphere, ending in the spinal cord

44
Q

True or false.

Gray matter of the spinal cord was set up developmentally.

A

True.

45
Q

The alar plate is (VENTRALLY/DORSALLY) located and is concerned with (SENSORY/MOTOR) components of the cord

A

Dorsally

Sensory (afferent)

46
Q

The basal plate is located (VENTRALLY/DORSALLY) and is concerned with the (SENSORY/MOTOR) components of the cord.

A

Ventrally

Motor (efferent)

47
Q

What is the butterfly shaped gray area divided into?

A
Dorsal horn (sensory)
Ventral horn (motor)
48
Q

The lateral horn (intermediolateral cell column) is present in what spinal cord segments?

A

Spinal cord segment T1-L2.

49
Q

What is located in the lateral horn?

A

preganglionic sympathetic neurons (a component of the ANS)

50
Q

What is found in sacral segments (S1-S3)?

A

Lateral horn contaning preganglionic parasympathetic neurons for the lower parts of the body- the other part of the ANS

51
Q

The gray matter is divided into various nuclei or divisions as a result of what? (2)

A

cellular (cytoarchitecture) and connectional studies

52
Q

What is Lamina of Rexed?

A

A system of 10 layers of gray matter (indicated by roman numerals)

53
Q

What is Lissauer’s Tract?

A

Dorsolateral tract present in the entirety of the spinal column. Carry pain and temperature information.

54
Q

What is the substantia gelatinosa (Lamina II)?

A

Located in the dorsal horn of the spinal cord, the substantia gelatinosa where first order neurons of the spinothalamic tract synapse.

55
Q

What is the nucleus proprius (Lamina III, IV)?

A

Located in the dorsal horn. It constitutes the first synapse of the spinothalamic tract carrying pain and temperature sensations from peripheral nerves.

56
Q

What is the dorsal nucleus of Clarke?

A

A group of interneurons in the the medial part of the base of the dorsal column. Serves as a relay center for unconscious proprioception.

57
Q

At what spinal cord segmental levels would you find the dorsal nucleus of clarke?

A

T2-L2

58
Q

What is the intermedilateral cell column (lateral horn)?

A

Area of the spinal cord that contains the autonomic motor neurons that give rise to the preganglionic fibers of the sympathetic nervous system.

59
Q

Where is the intermediolateral cell column/lateral horn found in the spinal cord?

A

Segmental levels C8/T1-L2, also segmental levels S1-S3

60
Q

What is located in the ventral horn?

A

Lower motor neurons

61
Q

Why do several areas and nuclei need to be identified in the dorsal horn?

A

Because it is concerned with incoming sensory information.

62
Q

What does nuclei refer to, in regards to spinal cord organization?

A

Refers to a group of cells with similar properties/connections

63
Q

True or False. Fibers that enter the cord via the dorsal roots are organized anterior to posterior.

A

False.

Organized medially to laterally.

64
Q

The most medially situated fibers are (SMALL/LARGE) diameter, (HEAVILY/LIGHTLY) myelinated, __, ___ and ____ type fibers

A

Large
Heavily
Ia/b, a-alpha, II

65
Q

The more laterally placed fibers are the (SMALL/LARGE) diameter, (MYELINATED/NONMYELINATED), type ___ fibers.

A

Small
Non-myalinated
Type C

66
Q

Intermediate fibers in the dorsal root are (HEAVILY/LIGHTLY) myelinated, type ___ fibers.

A

Lightly

A-delta

67
Q

Where do the axons from the cell bodies found in the ventral horn travel? What do they innervate?

A

Leave the spinal cord

Innervate muscles.

68
Q

What are lower motor neurons?

A

The cell bodies with axons that leave the spinal cord and innervate muscles.

69
Q

What is the final common pathway?

A

Concept that all motor control signals ULTIMATELY synapse on α-motor neurons.

70
Q

What two types of lower motor neurons are found in the ventral horn?

A

alpha motor

gamma motor

71
Q

How are the cell bodies of alpha and gamma motor neurons arranged within the ventral horn?

A

Those situated most medially are concerned with axial musculature (trunk, neck, etc)

72
Q

True or False. The cell column involving axial musculature extends throughout the entire length of the cord.

A

True

73
Q

The LMNs situated more laterally innervate what?

A

Muscles of the extremities.

74
Q

LMNs situated posteriorly in the ventral horn are concerned with what?

A

Muscles of flexion

75
Q

LMNs situated anteriorly in the ventral horn are concerned with what?

A

Muscles of extension

76
Q

What is formed by the merging of the dorsal and ventral roots away from the spinal cord?

A

The spinal nerve

77
Q

Prior to their merging, the dorsal root is (SENSORY/MOTOR/MIXED) and the ventral root is (SENSORY/MOTOR/MIXED.

A

Dorsal: sensory
Ventral: motor

78
Q

Once the dorsal and ventral roots combine the spinal nerve becomes (SENSORY/MOTOR/MIXED)

A

Mixed.

79
Q

True or False. The spinal nerve is a component of the PNS.

A

True.

80
Q

Each spinal nerve branches into a number of other branches to reach one of 2 areas:

A
  1. specific dermatomal segment

2. muscle of innervation

81
Q

What is associated with spinal nerves at levels T1-L2?

A

A series of autonomic ganglia.

82
Q

What is located at the ganglia of T1-L2?

A

postganglionic cell bodies for the SNS.

83
Q

Where are the preganglionic cell bodies located?

A

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

84
Q

What are reflexes?

A

Specific, stereotyped motor responses to an adequate (appropriate) stimulus.

85
Q

Reflexes require a series of structures consisting of a minimum of what 4 components? (complex reflexes may contain more connections in the CNS)

A
  1. Receptor
  2. Afferent limb
  3. Efferent limb.
  4. Effector organ
86
Q

What type of receptors are involved in reflexes?(2)

A
  1. Muscle spindles

2. GTOs

87
Q

What type of nerve endings are involved in reflexes? (2)

A
  1. encapsulated

2. Free nerve endings

88
Q

What is the role of the afferent limb in reflexes? Name a part of the nervous system involved in this.

A

Carries the impulse (stimulus) into the CNS

Example: dorsal root fibers

89
Q

What is the role of the efferent limb in reflexes? Name a part of the nervous system involved in this.

A

Carries the impulse for the response out of the CNS

Example: lower motor neuron (alpha motor)

90
Q

Give 2 examples of effector organs involved in reflexes.

A

Skeletal muscle

Glands

91
Q

What is an example of a stretch reflex or deep tendon reflex?

A

Patellar ligament/knee jerk

92
Q

What two concepts are demonstrated in a stretch reflex?

A
  1. Autogenic facilitation

2. Reciprocal inhibition

93
Q

What is autogenic facilitation?

A

The process of inhibiting the muscle that generated a stimulus while providing an excitatory impulse to the antagonist muscle.

94
Q

What is reciprocal inhibition?

A

The process of muscles on one side of a joint relaxing to accommodate contraction on the other side of that joint.

95
Q

What is the golgi tendon organ sensitive to?

A

tension when the associated muscle is conracted.

96
Q

At a certain point of increased tension on the GTO, what occurs? What is this known as?

A

The stimulus generates an inhibitory influence to the alpha motor neurons that are driving the contracting muscle

Known as autogenic inhibition

97
Q

What occurs once autogenic inhibition occurs?

A

The muscle can relax, releasing the tension.

98
Q

What is reciprocal facilitation?

A

Through the interneuronal pool, the antagonistic muscle can be activated to facilitate the release of tension.

99
Q

What reflexes are more complex than the tendon organ reflex?

A
  1. Flexor withdrawal reflex

2. Crossed extension reflex.

100
Q

What is the flexor withdrawal reflex?

A

is a spinal reflex intended to protect the body from damaging stimuli.

It is polysynaptic, causing stimulation of sensory, association, and motor neurons.

101
Q

What is the crossed extension reflex?

A

Occurs on the contralateral side of a the flexor withdrawal reflex, so that it can support the body when the flexor withdrawal reflex occurs.

102
Q

What must occur with the flexor withdrawal reflex and crossed extension reflex?

A

Reciprocal inhibition of antagonist or opposing muscle masses.

103
Q

What inhibitory circuits function in the flexor withdrawal and crossed extension reflexes? (3)

A
  1. Reciprocal inhibition
  2. Recurrent inhibition
  3. Non-reciprocal inhibition
104
Q

Reciprocal inhibition occurs where during the Flexor withdrawal/crossed extension reflex?

A

Antagonistic muscle

105
Q

Recurrent inhibition occurs where during the Flexor withdrawal/crossed extension reflex?

A

Same muscle and synergists via Renshaw cells (inhibitory interneurons)

106
Q

Non-reciprocal inhibition occurs where during the Flexor withdrawal/crossed extension reflex?

A

Agonists, synergists and antagonists (coordination of various movements)

107
Q

What structures are involved in segmental loss of the spinal cord. Be specific.

A

Involves the structures present at the specific segmental level. Includes:

  • gray matter areas of the cord
  • to some extent the dorsal and ventral root components that are bringing in sensory information and/or sending out motor information
108
Q

What is also involved but generally not included in the definition of segmental loss?

A
  • additional involvement of ascending and descending white matter pathways
  • in the real world, segmental losses will most likely include some involvement of this white matter