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Neuroanatomy > Lecture 2 > Flashcards

Lecture 2 Flashcards

1
Q

The ___ horn of the spinal cord is larger, and the ___ horn is smaller.

A

anterior, posterior

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2
Q

What is the difference between visceral efferent, and somatic efferent?

A

visceral efferent: motor to the vessels

somatic efferent: motor to muscles

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3
Q

What is the difference between the two types of somatic afferents?

A

one provides sensory sensation to the skin while the other is sensory to the muscles

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4
Q

Where are the different nerve types found?

A

anterior horn: somatic efferent (motor to muscles)
lateral horn: visceral efferent (motor to vessels)
posterior horn: somatic afferent (sensation to skin and muscles), and visceral afferent (sensory to vessels?)

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5
Q

___ are wrapped by extensions of meninges.

A

peripheral nerves

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6
Q

What are the three layers of meninges that can wrap peripheral nerves? Describe each.

A
  1. epineurium: most prominent around nerve trunks, provides tensile strength
  2. perineurium: continuous with arachnoid, the are the blood-nerve barrier
  3. endoneurium: surround individual nerve fibers
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7
Q

Describe myelin.

A
  • it is the membrane of a glial cell
  • covers up to 1 cm of axon
  • insulates axon membrane and increases conduction velocity
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8
Q

What is myelin produced by in the CNS? PNS?

A

CNS: oligodendroglia cells
PNS: schwann cells

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9
Q

The space between sections of myelin is know as ___?

A

the node of ranvier

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10
Q

Axons use ___ to convey signals

A

saltatory conduction

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11
Q

Describe saltatory conduction.

A

membrane depolarization occurs at the nodes, depolarization is renewed at the next node
**conduction proceeds in either direction

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12
Q

Where do local anesthetics act on nerves?

A

the nodes

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13
Q

___ cell membranes can wrap multiple axons and have no cytoplasm

A

oligodendroglial cells

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14
Q

Nerve fiber ___ correlates with function.

A

diameter

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15
Q

Receptor of taste, smell, pH, metabolite concentrations

A

chemoreceptors

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16
Q

Retinal visual receptors are ___.

A

photoreceptors

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17
Q

Receptors of temperature

A

thermoreceptors

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18
Q

Diverse receptors that respond to physical deformation, touch, muscle length and tension, auditory, and vestibular movements

A

mechanoreceptors

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19
Q

Pain receptors

A

Nociceptors

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20
Q

___ have many types of receptors that respond to position and movement.

A

joints

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21
Q

___ spindles are also propriorecptors.

A

muscle

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22
Q

___ receptors contain sensory nerve endings. Briefly describe them.

A

visceral receptors

  • mechanoreceptors: in walls of hollow organs
  • chemoreceptors: carotid body
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23
Q

Describe the general organization of receptors.

A

all have:

  • receptive area (may be specialized to detect adequate stimulus)
  • synaptic area: where message is sent to toward CNS
  • Turn a physical stimulus into an electrical signal (receptor potential) that the nervous system can understand
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24
Q

Receptor potentials encode ___ and ___ of stimuli. Some receptor systems are more sensitive than others so increased ___ may be reflected by the activated receptor.

A

intensity
duration
intensity

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25
Q

Each receptor has a ___, which conveys information about the location of the stimulus.

A

receptive field

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26
Q

Wiring patterns in ___ pathways to cortex preserve location and nature information

A

ascending sensory pathways

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27
Q

Sensory receptors become ___ sensitive to stimuli if they are maintained except for ___.

A

less

nociceptors (pain)

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28
Q

What type of sensory receptors are slowly adapting?

A

muscle spindle

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29
Q

What type of sensory receptors are rapidly adapting?

A

pancinian corpuscles, hair receptors

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30
Q

Adaptation occurs at ___ level, but the CNS can regulate sensitivity.

A

receptor

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31
Q

___ and ___ receptors detect limb position and muscle status.

A

joint and muscle

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32
Q

Muscles have ___ nerve endings

A

free

  • likely detect muscle pain
  • others are chemoreceptors, may be responsive to extracellular environment
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33
Q

What are the two types of encapsulated receptors?

A
  • muscle spindles

- golgi tendon organs (GTO)

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34
Q

Describe the function of muscle spindles.

A
  • detect muscle length (numerous in all skeletal muscles)
  • consist of a few small muscle fibers within (intrafusal) a capsule around the middle third of the fibers
  • ends of intrafusal fibers attached to extrafusal fibers, so when muscle is stretched, so are the intrafusal fibers
  • central area has sensory endings
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35
Q

Where are golgi tendon organs found, and what do they detect?

A

they are found in muscle-tendon junctions, and detect muscle tension.

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36
Q

What is the structure of golgi tendon organs?

A
  • consist of collagen bundles surrounded by a capsule
  • sensory fibers enter the capsule and branch amoung collagen bundles
  • muscle contraction distorts the capsule, stimulating sensory fibers.
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37
Q

If a muscle contracts isometrically, tension is generated across tendons and ___ are stimulated, but ___ won’t be activated as the muscle size has not changed.

A

GTOs

spindles

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38
Q

Relaxed muscle can be easily stretched and the ___ will be activated, but the ____ will experience little tension and remain inactive.

A

spindles

GTOs

39
Q

A muscle uses spindles and GTOs to monitor ___ and ___ simultaneously.

A

length and tension

40
Q

Briefly describe the construction of the spinal cord.

A

-it is organized into segments according to nerve roots (31 total segments: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal)

41
Q

Where do the dorsal rootlets of the spinal cord enter?

A

posterolateral sulcus

42
Q

Where do the ventral rootlets leave cord?

A

anterolateral sulcus

43
Q

Each dorsal root has a ___ , contains cell bodies of sensory neurons.

A

dorsal root ganglion

44
Q

Each spinal nerve inneravates one ___. (except C1, which has a rudimentary dorsal root)

A

Dermatome

45
Q

The caudal end of the spinal cord is known as ___.

A

conus medullaris

46
Q

There are two enlargements of the spinal cord where more motor neurons are found to supply lower and upper extremities. Where is each found?

A

cerivical enlargement: C5-T1

lumbar enlargement: L2-S3

47
Q

Which type of fibers enter the cord via the dorsal root, stay ipsilateral, and may terminate in the posterior horn or ascend to the medulla?

A

sensory afferent fibers

48
Q

What type of neurons are located in the anterior horns, leave through the ventral roots, and have their activity modulated by descending fibers from rostral structures?

A

Motor efferent

49
Q

What are stereotyped motor outputs that involve neural circuits contained in cord?

A

reflexes

50
Q

The dorsal intermediate sulcus is only found above level ___.

A

T6

51
Q

The dorsal intermediate sulcus is the spot that separates bundles of sensory fibers that arise from the ___ and ___.

A

leg: fasciculus gracillis
arm: fasciculus cuneatus

52
Q

The ___ is at the end of the anterior median fissure, and is the spot that the two sides of the spinal cord communicate through.

A

anterior white commissure

53
Q

The ___ at cervical and thoracic levels partially divides posterior funiculi.

A

posterior intermediate sulcus

54
Q

The spinal cord has an H shaped ___ core and is surrounded by ___.

A

gray matter

white matter funiculi (posterior PF, anterior AF, lateral LF)

55
Q

The posterior horn gray matter consists mostly of ___. These processes remain in the cord and projection neurons and axons collect to form ascending sensory pathways.

A

interneurons

56
Q

What is substantial gelatinosa responsible for?

A

pain and temperature

57
Q

Which tract has finely myelinated and unmyelinated fibers?

A

Lissauers tract

58
Q

What do the Rexed laminae of importance include?

A

lamina I: relays sensory signals
lamina II: substantia gelatinosa (important in pain)
Lamina V: relays sensory signals

59
Q

The gray matter of the ___ horn contain ___ neurons that control skeletal muscles.

A

anterior

motor

60
Q

What is the other name for lower motor neurons?

A

alpha neurons (this is our only means to move muscles and can be damaged weakening muscle movement or leading to paralysis)

61
Q

Alpha motor neurons cluster into groups, each of which innervates an individual muscle. What are the two main types of clusters?

A

axial muscles medial clusters

limb muscles lateral clusters

62
Q

Gamma-motor neurons innervate ___.

A

muscle spindles

63
Q

Alpha neurons innervate ___.

A

muscle fibers

64
Q

There are two special columns in the anterior horn at the cervical levels which are ___ and ___.

A 
Spinal accessory nucleus (caudual medulla to C5): forms the accessory nerve
Phrenic nucleus (C3, 4, 5): innervates the diaphragm and makes cervical cord injuries a serious issue because the patient can't breathe
65
Q

Intermediate to the two horns in the gray matter we have ___. neurons all of which are found in T1-L3.

A

preganglionic sympathetic neurons

66
Q

These preganglionic sympathetic neurons are all located in the ___ cell column.

A

intermedolateral cell column (lateral extension of gray matter)

67
Q

Axons from the preganglionic sympathetic neurons level through the ___ root and supply the ___ viscera.

A

ventral

pelvic

68
Q

S2-S4, sacral parasympathetic nucleus does not form a distant ___.

A

horn (the other levels have a small lateral horn that is visible)

69
Q

___’s nucleus is a collection of neurons found on the medial surface of intermediate gray matter from T1-L2.

A

Clark’s

70
Q

Clark’s nucleus serves as a ___ nucleus for transmission of info to the ____. It delivers proprioceptive info from the leg.

A

relay
cerebellum
(since its sensory, many consider it part of the posterior horn)

71
Q

The spinal cord as a whole gets smaller in diameter as we descend down the spine, but in particular you see less ___ and a larger amount of ___ and you proceed inferiorly.

A

white matter

gray matter

72
Q

In the 3rd month of fetal development, the cord extends the length of the embryo and nerves exit the intervertebral foramen at the ___.

A

level of origin

73
Q

In a newborn the vertebral column and dura lengthen relative to the cord. The end of the cord shifts ___ and nerves run ___.

A

upward

obliquely

74
Q

The cord is attached to dura by the ___

A

filum terminale (pia)

75
Q

The ___ nerve fibers run below the cord in lumbar cistern.

A

cauda equina (end of the cord is at L1/2 to end of dura at S2)

76
Q

What level is a lumbar puncture performed?

A

L4-5

77
Q

The ___ is the caudal cone-shaped end of the spinal cord.

A

conus medullaris (extends from L1-L2 interspace)

78
Q

The ___ consists of pia and arachnoid that extends from the conus medullar is to the coccyx.

A

filum terminale

79
Q

The ___ consists of dorsal and ventral roots and occupies the lumbar cistern

A

cauda equina

80
Q

The spinal cord is anchored by suspended ___ ligaments: pia-arachnoid extensions.

A

denticulate

81
Q

The ___ anchors the conus medullar is to the end of the dural sheath and then to the coccyx.

A

filum terminale

82
Q

Denticulate ligaments extend from the cord through the ___ to the ___.

A

arachnoid

dura

83
Q

What are the three things all reflex circuits require?

A
  1. a receptor
  2. associated afferent neuron (cell body in DRG)
  3. efferent neuron (cell body in CNS)
84
Q

All reflexes involve interneurons except ___.

A

stretch reflex

85
Q

Describe the stretch reflex.

A

the stretch reflex is the simplest reflex. it is monosynaptic so only 2 neurons and one synapse between them. Believed to be important during movements and maintaining posture.

86
Q

Stretch reflexes are also known as ___ since they are elicited by tapping on a tendon.

A

deep tendon reflexes (DTRs)

87
Q

What is the series of steps that occur to activate a stretch reflex?

A

strike ligament -> activates muscle spindle -> activates monosynaptic alpha motor neurons that innervate the stretched muscle

88
Q

lb fibers of the ___ have carrying effects depending on limb activity and position. They can be inhibitory or stimulatory.

A

Goligi tendon organ (Thought to contribute to fine adjustment in force of muscle contraction during muscle activity)

89
Q

The ___ artery runs down the spinal cord in the anterior median fissure and is formed from the ___.

A

midline anterior spinal artery

vertebral arteries

90
Q

The ___ artery is a branch of the posterior inferior cerebellar artery and runs in the ___ sulcus along the dorsal rootlets.

A

posterior spinal artery

posterolateral sulcus

91
Q

The spinal arteries supply ___, but are too small to supply other areas so they are supplemented by ___ arteries at lower levels.

A

upper cervical areas

radicular arteries

92
Q

The ___ artery is found at about T12 and is especially large. It is often a branch of a left posterior intercostal artery and it supplies blood to the entire ___ cord.

A

great radicular artery (artery of Adamkiewicz)

lumbosacral

93
Q

Although the anterior and posterior spinal arteries have extensive collaterals and anastomoses, where does each mainly supply?

A

anterior: anterior arteries including the anterior horns and a variable amount of lateral funiculi.
posterior: posterior horns and dorsal columns

Neuroanatomy (6 decks)

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