Chapter 13 - Spinal Cord Flashcards

1
Q

Functions of the Spinal Cord

A
  1. 2-way conduction pathway:
    a. ascending tracts -carry sensory info up spinal cord
    b. descending tracts - carry motor info down spinal cord
  2. Major reflex center - automatic responses processed here
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2
Q

Conduction

A

carry action potentials; AP can move up or down spinal cord bc lots of neurons

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3
Q

tracts

A

bundles of axons w/in CNS

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4
Q

Gross Anatomy of Spinal Cord

A

100 million neurons just in spinal cord; about 17 inches long; connected to brain; ends around L1 or L2; 3/4 inches thick; bottom-pointy; 31 pairs of nerves exiting spinal cord

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5
Q

Conus medullaris

A

bottom of spinal cord; pointy

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6
Q

2 thickened regions of spinal cord:

A
  1. Cervical region - Cervical enlargement-nerves that leave spinal cord & supplies the arms
  2. Lumbar region - Lumbar enlargement-neruons that control the legs
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7
Q

Cauda Equina

A

spinal roots relaying info below conus medullaris to exit points below conus medullaris

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8
Q

2 types of CT that protects the spinal cord

A
  1. filumterminale

2. denticulate ligaments

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9
Q

filumterminale

A

CT that connects conus medullaris & holds down the spinal cord to the coccyx so it doesn’t bounce around; like a rope

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10
Q

denticulate ligaments

A

CT that attaches spinal cord to vertebrae to hold in place (to the sides)

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11
Q

Protections of Spinal Cord (3)

A
  1. Vertebrae
  2. Meninges - CT that covers spinal cord (CNS); 3 layers of spinal cord coverings - dura mater, arachnoid mater, pia mater
  3. CSF - cerebrospinal fluid; cushions outside
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12
Q

Dura mater

A

outer layer of the spinal cord; toughest layer

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13
Q

Arachnoid mater

A

middle layer of the spinal cord; web-like attachments to pia mater

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14
Q

Pia mater

A

inner layer of the spinal cord; softest layer; richly vascularized; in direct contact w/spinal cord; only covering that nourishes (supplies O2 & nutrients) to spinal cord

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15
Q

Epidural space

A

space between dura mater & vertebrae; on top of dura mater; filled w/adipose tissue

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16
Q

Subdural space

A

thin layer under dura mater; holds serous fluid (lubricating fluid) to minimize damage

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17
Q

Subarachnoid space

A

fairly large space; filled w/CSF that cushions spinal cord

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18
Q

Layers of Meninges

A
  • Epidural space
  • Dura mater
  • Subdural space
  • Arachnoid mater
  • Subarachnoid space
  • Pia mater
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19
Q

White & gray matter

A

white matter-on outer part; mylinated axons; communication lines
gray matter - inner part; cell bodies; processing info; horns

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20
Q

Organization of Gray Matter in spinal cord

A

the below 2 are found in all parts of spinal cord:

  • posterior horn & anterior horn
  • lateral horns-only found in some parts of spinal cord
21
Q

Posterior horn

A

mainly cell bodies of interneurons; faces back of body

22
Q

interneurons

A

between sensory & other neurons

23
Q

anterior horn

A

mainly cell bodies of somatic (voluntary) motor neurons; relays info to skeletal muscle; direct contact with effector cells; motor neurons-away from CNS to effectors

24
Q

lateral horns

A

mainly cell bodies of autonomic motor neurons; only found in some parts of spinal cord; smooth muscle, cardiac muscle & glands-relays info to these places

25
Q

white matter

A

2-way conduction pathway; can carry info up or down spinal cord; many tracts

26
Q

Organization of white matter in spinal cord

A
  • ascending tracts (carry sensory info)
    a. gracile fasciculus
    b. cuneate fasciculus
  • descending tracts (carry motor info)
    a. lateral corticospinal tracts
    b. anterior corticospinal tracts
27
Q

gracile fasciculus

A

carries sensory info from lower body; mylinated axons

28
Q

cuneate fasciculus

A

carries sensory info from upper body (but not head); mylinated axons

29
Q

lateral & anterior corticospinal tracts

A

carry motor info from cerebral cortex to skeletal muscles

30
Q

PNS consists of

A

nerves (bundles of axons), ganglia (clusters of cell bodies in PNS) & sensory receptors (receiving end of sensory nerves (only in PNS); nerves make up majority of PNS

31
Q

Sensory receptors

A
  • exteroceptors
  • visceroceptors
  • proprioceptors
32
Q

exteroceptors

A

sense external stimuli; all receptors in skin; what’s going on around us (ex. touch sensors, pain sensors, pressure, merkel cells, free nerve endings, meissners corpuscles); sensory receptors

33
Q

visceroceptors

A

sense internal stimuli from visceral organs; ex. blood pressure, stretched muscle in stomach, chemical make-up of food eaten, chemical balance in blood; sensory receptors

34
Q

proprioceptors

A

sense stretch due to voluntary movements; 40% of body made of skeletal muscle; can detect how stretched every muscle is & know body position; needed for walking, muscle tone, posture; sensory receptors

35
Q

nerves

A

supply a particular part of body; relay info (does not control); richly supplied w/blood vessels; innervate-“supplies”

36
Q

Anatomy of Nerves: 3 CT coverings

A
  1. Endoneurium
  2. Perineurium
  3. Epineurium
37
Q

Endoneurium

A

inner most layer of nerve; CT surrounds each axon

38
Q

Perineurium

A

middle layer of nerve; CT covers each fascicle

39
Q

Epineurium

A

outer most layer of nerve; CT covers outside of nerve; covers entire nerve

40
Q

Classification of Nerves - classified by direction it carries info

A
  1. Sensory nerves - carry info towards CNS
  2. Motor nerves - carry info away from CNS to effectors (muscles or glands)
  3. Mixed nerves - some motor axons & some sensory axons; bundles 2 types of axons so they can carry info both towards & away from CNS; most abundant
41
Q

31 pairs of spinal nerves (PNS)

A

all mixed nerves; supply majority of body parts-arms, legs, most of trunk

42
Q

Name, order & # of nerves in spinal cord

A
  • top 8 pairs - Cervical nerves (C1 - C8) - C1 closest to brain
  • 12 paris - Thoracic nerves (T1 - T12)
  • 5 pairs - Lumbar nerves (L1 - L5)
  • 5 Pairs - Sacral nerves (S1 - S5)
  • 1 pair - Coccygeal nerves (C0)
43
Q

Spinal nerves are

A

mixed (sensory & motor); short; 1/2 - 1” long; exits each vertebrae; forms 2 branches - spinal roots

44
Q

spinal roots

A

2 branches of spinal nerve that is directly connected to spinal cord; always only one direction

45
Q

dorsal spinal root

A

connects to back of spinal cord; sensory only; into CNS; lots of cell bodies

46
Q

ventral spinal root

A

connects to front of spinal cord; motor only; out of CNS; no cell bodies; no ganglia

47
Q

mixed spinal nerve

A

where dorsal spinal roots & ventral spinal roots come together

48
Q

dorsal root ganglia

A

sensory ganglia; unipolar; located in middle