Spinal Cord Anatomy and Organization

Question 1

spinal cord length

Answer 1

foramen magnum to L2

Question 2

general function of spinal cord

Answer 2

sensory processory

• primary afferents enter spinal cord
• local - for simple reflexes (w/in level and side)
• ascending tracts

Question 3

motor neurons

Answer 3

efferents

LMN’s - cell bodies in ventral horn

Question 4

axons for motor neurons

Answer 4

go to periphery

Question 5

ventral horn cells

Answer 5

location of lower motor neurons

“final common pathway

Question 6

descending tracts

Answer 6

axons of upper motor neurons

from brainstem and cerebral cortex

Question 7

segmentation of spinal cord

Answer 7

based on vertebrae

8 cervical
12 thoracic
5 lumbar
5 sacral
1-3 coccygeal

Question 8

conus medullaris

Answer 8

around L2

end of spinal cord

Question 9

each segment of spinal cord

Answer 9

gives rise to pair of spinal nerve

-each has axons of dorsal root and anterior root

Question 10

spinal cord segment = ?

Answer 10

gives rise to 1 pair of spinal nerves

Question 11

dorsal root

Answer 11

has dorsal root ganglion

Question 12

each segment ?

Answer 12

innervates a dermatome

Question 13

2 enlargements of spinal cord

Answer 13

due to increased number of neurons
-associated with limbs

cervical enlargement - brachial plexus
lumbar enlargement - lumbosacral plexus

Question 14

cervical enlargement

Answer 14

brachial plexus

Question 15

lumbar enlargement

Answer 15

lumbosacral plexus

Question 16

gray matter

Answer 16

inner - butterfly shape

-has cell bodies

Question 17

white matter

Answer 17

outer

has cell processes (myelin)

Question 18

clinical orientation

Answer 18

looking up from feet as patient lies on back

Question 19

blood supply to spinal cord

Answer 19

differences will lead to different lesions depending on location of occlusion

Question 20

sacral cross section

Answer 20

round
mostly gray
very little white

Question 21

lumbosacral enlargement cross section

Answer 21

enlarged ventral horns - motor to lower limb
round shape
little white matter

Question 22

thoracic cross section

Answer 22

very little gray matter - not a lot of musculature
lots of white matter - lots of somatosensation

lateral horn - first presence

dorsal nucleus of clarke - central portion of gray

Question 23

lateral horn

Answer 23

T1-L2
- preganglionic sympathetic cell bodies
aka IMLCC

Question 24

dorsal nucleus of clarke

Answer 24

center of gray matter - thoracic cross section

proprioception to cerebellum

Question 25

cervical enlargement cross section

Answer 25

oval shape enlarged dorsal and ventral horns lots of white matter

Question 26

flexors

Answer 26

more posterior in ventral horn

Question 27

extensors

Answer 27

more anterior in ventral horn

Question 28

proximal muscles

Answer 28

more medial in ventral horn

Question 29

distal muscles

Answer 29

more lateral in ventral horn

Question 30

three general types of white matter in SC?

Answer 30

long ascending long descending propriospinal (short)

Question 31

long ascending tracts

Answer 31

thalamus cerebellum brainstem

Question 32

long descending tracts

Answer 32

upper motor neurons - to lower motor neurons from cortex from brainstem

Question 33

propriospinal fibers

Answer 33

short - within spinal cord -connect different cord levels coordinate reflexes

Question 34

posterior funiculus below T6

Answer 34

below T6 - known as fasciculus gracilus somatosensation from lower limb

Question 35

fasciculus gracilus

Answer 35

posterior funiculus caudal to T6 somatosensation from lower limb

Question 36

posterior funiculus above T6

Answer 36

fasciculus gracilus | and also fasciculus cuneatus

Question 37

fasciculus cuneatus

Answer 37

posterior funicullus above T6 primary afferents somatosensation from upper limb

Question 38

anterolateral system

Answer 38

anterior and lateral funiculus - somatosensory fiber tracts - ascending secondary, tertiary, quarternary neurons - carrying axons from contralateral side**

Question 39

spinocerebellar tracts

Answer 39

somatosensation to cerebellum (not conscious) up lateral funiculus -ascending secondary and third order neurons

Question 40

corticospinal tracts

Answer 40

descending tract lateral funiculus descending upper motor neurons final synapse - ventral horns - to LMNs

Question 41

spinal cord reflexes

Answer 41

motor event driven by sensory stimulus ex/ withdraw, pupil constriction local - can operate without UMN input (from cerebrum) program pattern generators

Question 42

reflex arc

Answer 42

``` 1 receptor 2 afferent neuron 3 interneurons (s) 4 efferent neuron 5 target organ ```

Question 43

local circuits

Answer 43

can still operate with lesion in spinal cord above or below

Question 44

brainstem

Answer 44

continuation of the spinal cord performs spinal cord like functions for head - gives rise to cranial nerves - initial processing for sensory from head - LMNs for muscles of head vital reflexes relay for all info

Question 45

conduit functions of brainstem

Answer 45

ascending tracts to thalamus and cerebellum descending tracts to SC many relay nuclei in brainstem

Question 46

cranial nerve functions of brainstem

Answer 46

afferent and efferent info | special sensation

Question 47

integrative functions of brainstem

Answer 47

complex motor patterns (chewing, swallowing) | cardiovascular and respiratory functions

Question 48

rostral medulla

Answer 48

open fourth ventricle

Question 49

caudal medulla

Answer 49

closed fourth ventricle (central canal)

Question 50

pyramidal decussation

Answer 50

level of inferior edge of medulla | -outcropping of cells - location of crossing of corticospinal tract fibers

Question 51

pyramids

Answer 51

left and right on medulla - location of corticopsinal fibers - UMNs - to voluntary movement

Question 52

olives

Answer 52

laterally on medulla

Question 53

pre and post olivarry sulcus

Answer 53

on medulla aorund olives

Question 54

pons division

Answer 54

basal pons tegmentum

Question 55

basal pons

Answer 55

does NOT connect two hemispheres

Question 56

cerebellar peduncles

Answer 56

fibers from pons to cerebellum superior middle inferior

Question 57

midbrain

Answer 57

cerebral peduncles -fiber bundles from cerebral cortex colliculi

Question 58

colliculi

Answer 58

two superior | two inferior

Question 59

cranial nerve 4

Answer 59

right below the inferior colliculi

Question 60

brainstem

Answer 60

tectum | tegmentum

Question 61

tegmentum

Answer 61

reticular formation - nuclei throughout brainstem cranial nerve nuclei (LMNs) tracts (ascending and descending)

Question 62

substantia nigra

Answer 62

makes it easy to pick out midbrain | -dopaminergic cell bodies