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Anatomy (Pharm 110) > 6.4 Spinal chord > Flashcards

6.4 Spinal chord Flashcards

1
Q

Describe spinal chord - where does it end? what are its functions?

A
  • Location
    • in vertebral column
    • begins at foramen megnum (continuous with medulla)
    • adult ~42 cm long
    • ends at Conus medullaris at L1
  • Functions
    • provides two way communication to and from brain
    • contains spinal reflex centres
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2
Q

Ho many spinal nerves do we have?

where do they exist?

A
  • 31 pairs
  • c1-c7 exit above vertebrae of same #

*have 7 cervical vertebrae but 8 nerves

  • all other exit below vertebrae
  • has cervicla and lumbar enlargements (info for upper and lower limbs comes in and out)
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3
Q

How many nerves are in cervial, thoracic, lumbar, sacral and coccygeal areas?

A

Cervial: 8

Thoracic: 12

Lumbar: 5

Sacral: 5

Coccygeal: 1

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4
Q

How is the spinal chord protected?

A
  • Bone, meninges, and CSF (in subarachnoid space)
  • cushion of fat and network of viens in epidural space between vertebrae and spinal dura mater
  • Denticulate ligaments: lateral extensions of pia pater that secure cord to dura mater
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5
Q

spinal chord proteciton at lower level

A
  • dural & arachnoid mater extend to S2
  • cauda equina: collection of nerve roots inferior to conus medullaris in subarachnoid space

*ext from end of spinal chord to subsrachnoid space

Filum terminale: extension of pia mater from conus medularis -> coccyx

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6
Q

What do you see if you take a cross section of the spinal chord?

A
  • divded by 2 lengthwise grooves: sep left and right halves
  • Ventral (anterior) meidal fissue
  • Doral (posterior) median fissue
  • gray commissure: connects masses of gray matter; encloses central canal

*basiaclly ther is a groove in the fron and back that divides left and right

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7
Q

What anchors the spinal chord superiorly? Posteriorly?

A

Superiorly: brain stem

Inferiorly: filium terminale

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8
Q

Describe Gray Matter

A

Ventral Horns: somatic motor neurons whose axons exit via ventral roots (motor)

lateral horns: only in thoracic & lumbar regions (motor)

dorsal horns: interneurons receiving somatic an dvisceral sensory input

-> dorsal root anglia: cell bodies of sensory neurons (on dorsal)

* looks like butterfly in middle of spinal chord, note in cerebral hemiphsere gray was on the outside

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9
Q

Describe the nerve innervation of spinal chord gray mater

A

Somatic sensory neuron: interneurons receiving input from somatic sensory neuron

Visceral sensory neuron: interneurons receive input from visceral sensory neurons

Visceral Motor neuron:

Somatic motor neurons:

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10
Q

what pathway generalizations are made in spinal chord

A
  • Either ascending (sensory, coming up to brain)) or descending (motor, brain tells body how to move)
  • Most pathways decussate (cross over)

*allows left brain to comm ith right body

  • Most exhibit somatotopy (precise spatial relationships)
  • Pathways are paired symmetrically (one on each side of spinal cord or brain)
  • Name of pathway often gives information on start & end
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11
Q

Describe White matter in the spinal chord

A
  • in spinal tract: collections of axons with similar functions
  • consists of bilateral tracks in 3 white columns (funiculi)
  • > Ascending/Sensory tracts (Dorsal, Lateral + Ventral columns)
  • > Descending/Motor tracts (Lateral + Ventral columns)
  • >Transverse tracts (commissural fibers) cross from one side to other
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12
Q

Describe the big picture of the ascenting pathway

A
  • First orer neuron
    • conducts impulses from cutaneous receptors (skin) and proprioceptors (awareness of body in space)
    • Branches diffusely as it enters spinal cord or medulla
    • Synapses with second-order neuron
  • Second - order neuron
    • in CNS
    • interneuron
    • cell body in dorsal horn of spinal chord (grey matter) or medullary nuclei
    • axons extend to thalamus or cerebellum
  • Third order neuron
    • interneuron in CNS
      cell body in thalamus
    • axons exten to somatosensory ortex
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13
Q

What 2 pathways transmit somatosensory info to sensory cortex

A

does this via thalamus

  1. Dorsal column-medial lemiscal pathway (DCML)
  2. Spinothalamic pathway (anterolateral pathway) (pain and temp path
    - spinocerebellar tracts terminate in Cerebellum (unconscious processing)
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14
Q

what information does Dorsal Column- Medial Lemniscal (DCML) Pathway transmit

A

discriminative touch & vibrations

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15
Q

decribe pathway of Dorsal Column- Medial Lemniscal (DCML) Pathway

A

1a. information comes in dorsaly from touch receptor -> dorsal column white matter highway (lower limbs)
1b. info comes in from proprioceptor, through spinal nerves -> doral root ganglion
2. info crosses (decussation) at medulla oblongata -> first order nueron synpase on 2nd order neuron
3. 2nd roder nueron ends in thalamus (exact location depends on where in body sensation was)

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16
Q

What information does the lateral spinothalamic tract transmit

A

pain and temperature impulses

17
Q

what info does ventral spinothalamic tract transmit

A

crude touch and pressure impulses

18
Q

pathway of lateral spinothalamic tract

A
  • info from temperature and pain receptors -> can come from doral root
  • first neuron synpases on dorsal horn, get decussion at level of entry

*synases as level where it enters and crosses over

  • 2nd neuron synapses in thalamus then sends 3rd neuron to primary somatosensory cortex
19
Q

What information does the spinocerebellar tract convey?

A
  • impulses from trunk and lower limb proprioceptors -> same side of cerebellum for subconscious porprioception

*same side of brain controls same side of body affected

20
Q

pathway of spinocerebellar tract

A
  • only 2 neurons
  • has lateral dorsal and lateral ventral part

*does not go to thalamus

  • info from muscle spindle (proprioceptor) togoes to interneurons of dorsal horn
  • ipsilateral: dorsal never crosses, ventral crosses then crosses back

*same side of body communicated with same side of the brain

  • synases at level it enders, terminates by synapse in cerebellum

* NOT IN UPPER LIMBS, transmits impulses from trunk & lower limbs

(blue pathway in image)

21
Q

Describe the big picture of descending pathways: what are the two types of pathways and what neurons do they involve?

A
  • deliver efferent impulses from brain to spinal cord
  • > Direct pathways: Corticospinal/pyramidal tract
  • > Indirect pathways: all the others one

Involves:

  • > Upper motor neurons: cortex to spinal cord
  • > lower motor neurons: spinal chord ot skeletal muslce (ventral horn motor neurons
22
Q

describe the direct pathway

A

aka Pyramidal Tract or Corticospinal Tract

  • impulses from pyramidal enurons in precentral gyri pass through pyramidal tracts (upper motor neurons)

^ first neuron in pathway

  • axons synpase with interneurons or ventral horn mototr neurons (lower motor neurons)

*regulares fast and fine (skilled) movements

23
Q

describe pathway of direct pathway

A
  1. starts in cell body of Pyramidal cells (upper motor neurons) of cerebrum

^in primary cortex, sends info around thalamus

  1. Lateral: decussate in pyramids of medualla (85%). Ventral cross over at spinal chord level (15%)
  2. termination with ventral horn interneurons
24
Q

describe the indirect (extrapyramidal) system pathway

A

*Pathways are complex & multisynaptic

  1. Tectospinal tract: mediate head movements in responds to visual stimuli (contralateral)
  2. Vestibulospinal tract: maintain balance duringstanding & moving (Ipsilateral)
  3. Corticobulbar tract: motor to skeletal muscle of cranial nerves (both contralateral & ipsilateral)
25
Q

if you sever left side of spinal chord in thoracic region what would happen

A

* T3 only impacts lower limbs, everything that happens above could get thouse

*loss of ability would be confined to one side

  • DCLM: General touch
    • crosses in medualla
    • information on left could not get thorugh -> lostt general touch on left
  • Latspinothalamic
    • crosses @ level it enters
    • loss pain and temp on right (below lesion)
  • Lateral corticospinal
    • crosses at medulla
    • loss movement on left below lesion
26
Q

what are teh 3 levels of motor control

A

precommand level (higihest)

projection level (middle)

segmental level (lowest)

27
Q

describe the precommand level of motor control

A
  • highest
  • cerebellum (makes music sound good) and basal nuceli (when to start/end music)
  • rpograms and instructions (modified by feedback) -> doesnt make the movement itself
28
Q

Describe the projection level of motor control

A

(middle level)

  • motor cortex (pyramidal pathways) and brain stem nuclei (vesticular, red, reticular formation etc)
  • converys instructions to spinal chord motor neurons and sends a copy of that info to higher levels

*communicated with precommand and segmental levels

29
Q

describe the segmental level of motor control

A
  • spinal chord
  • contains central pattern generators

Anatomy (Pharm 110) (41 decks)

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