Chapter 14- Spinal Cord and Spinal Nerves Flashcards Preview

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Flashcards in Chapter 14- Spinal Cord and Spinal Nerves Deck (44)
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1

spinal cord: gross anatomy

-part of the CNS
size and location:
-slender nerve column
-about 45cm long
-starts at foramen magnum and ends between L1 and L2 (does not go into the sacrum)
-31 pairs of spinal nerves

2

overall structure

-bilateral symmetry
-consists of both gray and white matter

3

central canal

hole down the center of cord; continuous with brain ventricles; both contain CSF

4

2 grooves of spinal cord

anterior median fissure
posterior median sulcus

5

enlargements

swollen regions of spinal chord
named based on region
-cervical enlargement
-lumbar enlargement

6

conus medullaris

inferior most tip of spinal cord; cone shaped

7

cauda equina

means horse's tail; bundle of nerves inferior to spinal cord

8

filum terminale

inferior most spinal nerve

9

gray matter

-cell bodies, dendrites and synapses
-projections called horns
-cell bodies organized into nuclei
--sensory
--motor

10

interior horns

posterior horn
anterior gray horn
lateral gray horn

11

gray commissure

anterior commissure
posterior commissure
(separated by central canal)

12

white matter

tracts and columns
-posterior white column
-ant. white column
-lateral white column
-ascending tract=sensory
-descending tract=motor

13

meninges

membranes covering CNS
-are similar in both brain and spinal cord
-are split into layers called 'mater' (mother)

14

superificial to meninges

vertebrae consists of vertebral arches
-epidural space
-space between meninges and vertebra
-contains BV and adipose
meninges connect to CT of spinal nerves

15

spinal meninges: dura mater

tough mother
-durable
-deep to epidural space
-superficial to subdural space
-stabilized by coccygeal ligament

16

spinal meninges: arachnoid mater

spidery mother
-superficial to suarachnoid space
-contains CSF
-CT looks like a spider web

17

spinal meninges: pia mater

delicate mother
-light layer adhering to cord
-forms part of filum terminale

18

spinal meninges order

vertebrae
epidural space
dura mater
subdral space (with CSF)
arachnoid layer
subarachnoid space
pia mater
neural tissue

19

spinal nerves

31 pairs
-8 cervical (with 7 cervical vertebrae)
-12 thoracic
-5 lumbar
-5 sacral
-1 coccygeal

20

nerve components

dorsal root
-dorsal root ganglion
-usually sensory
ventral root
-no ganglion
usually motor

21

nerve components (cont)

roots merge to form nerves
-hence spinal nerves usually are mixed (sensory and motor)
-all roots go through intervertebral foramen

22

epineurium

surrounds the entire nerve

23

perineurium

surrounds bundles of 10-100 axons (known as fascicles)

24

endoneurium

surrounds each individual axon of each neuron

25

Rami

offshoots of a nerve once it exits the vertebrae

26

3 types of rami

dorsal ramus
ventral ramus
ramus communicantes

27

ramus communicantes

a splitting in the ramus separating sensory and motor fibers
white ramus communicantes
grey ramus communicantes

28

dermatomes

sensory innervation by specific spinal nerves
-spinal cord damage will result in loss of sensation in dermatome
-detection method

29

nerve plexus

braid off ventral rami
interconnected web of nerves for greater innervation
-found in several regions
-cervical
-lumbar
-sacral
(most thoracic nerves are all isolated

30

cervical plexus

C1-C4 and part of C5
-innervate certain muscles of neck and torso

31

phrenic nerve

C3, 4 and 5
goes to diaphragm
results in breath
-part of cervical plexus

32

brachial plexus

C4-C8 and T1
innervate the chest, upper back and arm

33

brachial plexus nerves

musculocutaneous
-to ant. muscles of arms and skin of forearm
ulnar nerve
-to muscles of forearm, hands and skin of hands
median nerve
-same as ulnar
-between radius and ulna
radial nerve
-to post. muscles of arms and skin of forearms and hands

34

lumbosacral plexus

last thoracic, lumbar, sacral and coccygeal nerves
may be split into lumbar and sacral plexuses

35

lumbosacral plexus nerves

innervate the lower limb regions
obturator nerve
-to adductors of leg
-femoral nerve
-motor impulses to leg and thigh and receive sensory from skin of leg and thigh
sciatic nerve
-to muscles and skin in thighs, legs and feet

36

reflexes

-rapid automatic involuntary motor response to stimuli
-help preserve homeostasis
-occur at spinal cord or brain stem
-do not require cerebral processing
-can be modified by cerebral control

37

classification of reflexes

-by development
-site of processing
-nature of motor response
-complexity of neural circuit

38

classification by development

genetically: built in (innate)
learned: acquired through repetition and/or experience

39

classification by site of processing

spinal reflex: impulse only goes to spinal cord
cranial reflex: makes it to the brain

40

classification by nature of motor response

somatic: influences the skeletal muscles system
-purely effector based skeletal muscle in this case
visceral (autonomic): influences the involuntary systems such as smooth muscle and glands

41

classification by complexity of neural circuit

how many synapses are involved
-monosynaptic=1
-polysnaptic=2 or more

42

steps of a reflex arc

1. receptor is stimulated by a detectible environmental stimulus
2. receptor stimulates a sensory neuron that sends a signal to the CNS for processing
3. information is processed by being transmitted to the appropriate neurons
-this could be a n interneuron or motor neuron
4-5. motor neuron is stimulated, sending a signal to an effector. this results in a behavior

43

stretch reflex

a reflex stimulated by the stretching of a muscle
-muscle spindle fibers are receptors that detect stretching
-effector is the contraction of the muscle

44

patellar reflex

patellar reflex is a stretch reflex
-functions to:
-prevent muscles form being overstretched
-prevent one from falling forward