Chapter 18: Spinal region

Question 1

anatomy of spinal cord

Answer 1

L1-L2 endpoint of spinal cord in adults.
-cauda equina is below L1 and L2 (axons and dorsal and ventral roots traveling down in spinal column to the point where they join together and become a spinal nerve going outside).

Cervical and lumbar parts of spinal cord are bigger (swollen up and enlarged)- cervical= a lot of arm neurons in the cervical spinal cord and a lot of leg neurons in the lumbar spinal cord. both are predisposed to traumatic injury.

Question 2

Dorsal root organization: medial group

Answer 2

Sensory axons in dorsal root medial group and lateral group.
Medial- do not enter the dorsal horn, they bypass it. Go in dorsal root and go straight to dorsal column where they turn and go up (don’t synapse in the spinal cord= dorsal column medial lemniscus pathway- discriminative touch and conscious proprioception.

Lateral- enter the dorsal horn and synapse there, fibers of spinothalamic (pain and temperature pathway). After synapse it crosses the middle first and then goes up spinal column.

Question 3

Spinal segments

Answer 3

the part of the spinal cord that has all of the neurons associated with one spinal nerve. Part of spinal cord that has all of the axons associated with one spinal nerve.

Question 4

anatomy of spinal region (white matter columns)- sensory

Answer 4

Dorsal column medial lemniscus system- back portion of spinal cord.

Spinocerebellar tracts- (hands on hips=location of the tracts) carry nonconscious proprioception and light touch- goes to the cerebellum.

Anterolateral system- pain (4 pathways in the system= spinothalamic pathway (discriminative pain and temp), reticulospinal- (helps wake me up), Spinomesencephalic (helps orient head to the source of pain and start a pain pathway back down the spinal cord), Spinoemotional pathway- (emotional response and autonomic response to help maintain homeostasis.

Question 5

Anatomy of spinal region (white matter columns) motor

Answer 5

Lateral group of UMN- controls distal parts of our extremities (hands and feet) cortical group gives a lot of control.
-Lateral corticospinal tract- cell bodies are in the more lateral aspect of the ventral horn/column.

Medial UMN- medial corticospinal- control protraction and retraction of shoulder blade.

• medial and lateral vestibulospinal- help keep us up against gravity.
• Reticulospinal- helps pick stuff up against gravity.

Autonomic column- comes right down the side of the spinal cord, control neurons that start in pons and medulla extend down the spinal cord.

Question 6

Dorsal horn

Answer 6

cell bodies of sensory pathways

Question 7

lateral horn

Answer 7

cell bodies of peripheral autonomic pathways. Not in cervical because the output of autonomic system doesn’t start until T1

Question 8

Ventral horn

Answer 8

cell bodies of LMN and the regional organization is proximal is medial and distal is lateral.

Question 9

Meninges

Answer 9

In spinal cord the meninges continue down and wrap the spinal cord.

Inside the dura (meninges) part of cauda equina, outside of meninges is the epidural space. IF a reason to pull cerebrospinal fluid for analysis is inside the meningeal system so if they draw the spinal tap down in the low lumbar or upper sacral area, needle going through the dura is less likely to poke spinal cord.

Anesthetic can be done around the dura which will diffuse through and is much safer procedure.

Question 10

blood supple of spinal cord

Answer 10

rich blood supply-

two posterior spinal arteries

one anterior spinal artery.

medullary artery that connects the two

Question 11

function of the spinal cord

Answer 11

Transmits information in columns (up and down) but it also processes information at synapses (the dorsal horn synapse of the pain pathway and the UMN to LMN synapse in the ventral horn (activate LMN in ventral horn)

• only dorsal column pathway passes through spinal cord without synapse.
• processes and or modifies information

Question 12

spinal cord convergence

Answer 12

convergence of multiple inputs on A-alpha
-20,000 synapses on a single A-alpha

LMN give us final signals to do what we want to do. A-alpha is active or not active based on the sum of all incoming signals.

clinical examples: deep tendon pressure for inhibition
- inhibition meets contraction signal and may help the muscle to not contract as much.

Question 13

reflexes (phasic stretch

Answer 13

stimulus is stretch- stretching muscle spindles and sending muscle signals into the spinal cord and synapsing with LMN. Stretch biceps and contract biceps

Withdrawal crossed extension- multi joint and multimuscle reflex contraction (because pain neurons branched to multiple levels of the spinal cord once they go into the dorsal root)

Question 14

spinal control of pelvic organs

Answer 14

Frontal center= modulatory (frontal lobe- decides if it is okay to go)

Pontine center= control (extends down the spinal cord towards segments that control bowel and bladder- will either help turn on or help turn off emptying of bowel and bladder.

Reflex loop- when bladder stretches it sends signals to the spinal cord and the spinal cord sends a reflex response back out. (parasympathetic- controls bladder to contract and bladder to open) (sympathetic- not to open and not to contract the bladder)

voluntary control over external sphincter

Spinal cord centers

• efferent- pre-ganglionic SNS and PNS
• afferent- from bladder wall (stretch sensation)

Question 15

spinal control of pelvic organs

Answer 15

Frontal lobe- modulation

Brainstem-control

Spinal cord- reflex loop

Question 16

spinal control of pelvic organs

Answer 16

Parasympathetic efferent
-contracts bladder to empty it

Sympathetic efferent
-relaxed bladder to not empty it

Somatic efferent
-can voluntarily contract “external sphincter”

Stretch of bladder wall
-initiates emptying reflex (sacral spinal cord)

Bladder wall stretches (as bladder fills up)
-stretch activated afferents (alerts brain that bladder is filling, initiates emptying reflex (at spinal cord level)).

Question 17

spinal control of pelvic organs

Answer 17

If okay to go

• higher centers allow emptying reflex
• higher centers voluntarily relax external sphincter

If not okay to go

• higher centers try to sop emptying reflex
• higher centers voluntarily contract external sphincter.

Question 18

segmental vs tract lesions

Answer 18

damage that happened at a segment s the vertical tracts, the columns that go up and down.

one spinal nerve- paresis of muscles innervated by C5 and C6 combines with loss of all sensory information.

If only half the cord gets cut- light touch from ankle starts at surface of the skin and neuron goes up and gets in spinal cord and stays on the same side all the way up to the medulla before it crosses the midline
-if damage to the right side of my spinal cord, I would lose light touch sensation in the right leg.

Pain and temp- If right side spinal cord gets cut then I lose pain sensation in left leg because it crosses right as it goes into the spinal cord.

Question 19

Voluntary movement

Answer 19

Lateral corticospinal neurons that start on one side of the brain cross over in the decussation of the pyramids (the caudal medulla) then they travel down the spinal cord to innervate muscles on that same side. At T10 on right side the right quadriceps would be affected.

UMN that start in the cortex cross over inn the medulla. Loss of motor function on the same side as the damage in spinal cord.

Question 20

Segmental vs tract lesions

Answer 20

segmental lesion- C6 segment on right deprives C6 segment of input and blocks all of its output. not motor can exit

Tract lesion- sensory tracts of spinal cord can bypass the injury with no problem because they are inside the spinal cord. One segment is broken but the tracts up and down are still in tact.

Question 21

segmental vs tract lesions- sensory loss

Answer 21

sensory loss is on the same side of the injury when it is out of the spinal cord.

Pattern of sensory loss- dermatomal loss of sensation.
strength of the biceps would be weak because the segment contains some but not all of biceps innervation.
-hyporeflexic because some of the normal reflex has been interrupted.

Normal quadriceps strength because the tracts that supply them goes right by the damage site.

Question 22

signs and symptoms in “segmental” pattern

Answer 22

• dermatomal sensory loss
• myotomal motor loss
• • if only one segment is damaged, then weakness
• • hypotonia (due to some LMN damage)
• -hyporeflexia (due to some LMN damage)

Autonomic loss in one segment- the patient will likely have slightly redder skin and will have impaired sweating in the C6 dermatome.

Question 23

dot representation of sensory loss

Answer 23

Dot is representative of the entire dermatome. IF patient can feel sensation at point of dot then you can feel good that the rest of the sensation in dermatome region is in tact. If they cannot then you have to go through the dermatome and find the point were sensation is felt.

Question 24

complete block of C6 segment

Answer 24

completely taken out the C6 segment and completely blocked the tracts as well. Complete C6 segment has been crushed.

Vertical tracts now impaired and no sensory or motor tracts can ascend or descend past the C6 level.
-No autonomic control can descend past C6 level.

Question 25

Signs and symptoms in tract patter

Answer 25

-Sensory loss in all segments below lesion

-Motor loss in all segments below lesion
paralysis (UMN damaged-atrophy of disuse)
Hyperreflexia (UMN damaged- hypersensitivity)

-Autonomic loss in all segments below lesion.

Complete bilateral spinal cord injury.

tract injury is C7 and below.

Question 26

reality of complete spinal cord injury

Answer 26

Reality of this patient is that no sensory can get in C6 and no sensory can get up past C6. this person loses all their sensation at C6 and all the levels below. C7 and below is tract damage, reality is they cant fell anything at C6 or any level below.

Biceps weak because the C6 contribution is gone. only C5 contribution now.

Question 27

Anterior cord syndrome

Answer 27

T10 will not be able to actively contract quadriceps due to corticospinal lesion, will not be able to feel pain and temp due to anterolateral damage. No pain signal below T10 will be able to make it back.
-tested light touch and knee proprioception. Because dorsal columns are largely in tact there is a high likelihood they can feel touch and will have proprioception.

Question 28

Central cord syndrome

Answer 28

Central cord collapsed: meninge/water balloon fills up from the inside out.
-inflating water balloon can press on what is around it from the inside out.

-Pain neurons cross the back and cross middle before going to the anterolateral- will lose pain and temp sensation everywhere that the water balloon damages the central spinal cord.

Perfect pain and temp at C6 and C5 but as it starts to fill they start to lose it at C6 and at C5. Start to lose it going up from the point of injury.

• can start to press on ventral horns and will most likely lose control of shoulder and proximal muscles at point of central cord syndrome.
• typically touch and proprioception are not bothered.

Question 29

Brown-sequard syndrome (hemi-section)

Answer 29

Hemi section-

Damage on left side of spinal cord leads to:

Lose touch on same side as the cut (SAME)
I lose motor control on the left- ipsilateral (SAME)
Pain- lose pain sensation in the right leg (OPPOSITE)

Question 30

injury to cauda equina

Answer 30

axons from the ventral and dorsal roots coming down inside the spinal column waiting to join and poke out as spinal nerves.
-Would come out as LMNs and peripheral somatosensory neurons.

Cauda equina damaged at L2- (all at that level and below)

• not able to contract quadriceps- atrophy of denervation and all other muscles enervated by segments below.
• Patellar reflex- hyporeflexive because the reflex loop itself has been cut (LMN cut and peripheral somatosensory neurons cut)

Lose sensation at L2 and below.
-spinal cord never gets the full bladder message so the bladder will blow up due to being overfull (bladder reflex is broken)

Question 31

spinal dysfunction

Answer 31

Damage above S2, S3, and S4 the bladder still has reflex loop but no control of that loop from above that make it hypersensitive reflex (hyperreflexive bladder) fills up and the sacral spinal cord says okay lets empty and nothing from above to control it.

Question 32

spinal dysfunction at S2, S3, and S4

Answer 32

Spinal cord will never know when the bladder is full and the spinal cord can never say okay let me empty it for you (hyporeflexive bladder) it will fill up until the pressure overfills the sphincter and starts to leak.

-Insert catheter to drain before it empties or leaks. Strategy is to drain it intentionally.

Question 33

most common causes of spinal cord injury

Answer 33

• MVA (#1 cause- especially cervical spine)
• sports injuries
• falls
• penetrating wounds

Question 34

Spinal shock

Answer 34

a period of time after a spinal cord injury where every neuron below injury shuts down from shock and is non functional

Injury at C8 and for a few days no reflex below C8 worked and over time the shock wears off and the LMN become hyper excitable

Question 35

Additional changes in muscle

Answer 35

Atrophy-
Spinal cord is atrophy of disuse
Cauda equina- atrophy of denervation

• fibrosis
• contracture (hip flexors)(knee flexors)

Question 36

classification of spinal cord injuries

Answer 36

Complete vs Incomplete
- lowest sacral segment is key to differentiating

test sensory and motor function of S4 and S5 to test anal function. If they can feel and contract then both sensory and motor are incomplete.

Neurological level- Lowest level with normal sensory and motor function (normal motor at least 3/5 on MMT) for key movements.

Question 37

ASIA scale

Answer 37

Go through key movements and area of sensation for finding out spinal level of damage.

Question 38

Autonomic Dysfunction

Answer 38

Autonomic Dysreflexia (hyperreflexia)
-No parasympathetic control past C8

-All visceral reflexes are hyperreflexia (can be life threatening due to increase in BP and sweating to the level of lethality, most common cause is a full bladder. Body tries to mobilize a flight or fight response (clamps down arteries of legs and arms so that muscles that need blood can open and get blood which greatly increases blood pressure with a really bad headache).

Find the source as best we can and eliminate it.

Question 39

impaired temperature regulation

Answer 39

not able to shunt blood away from the surface (sympathetic all gone and there is always blood at the surface of the skin) control of ympathetics is T1 and poke out and go up to the cervical.
-Nowhere on the body will a person sweat with a T8 injury with a C8 injury (not able to regulate temperature.

Question 40

Orthostatic hypotension

Answer 40

Venules stay floppy and don’t squeeze venules to get blood back into circulation. Has impaired capacitance.

-muscles are not contracting which helps pump blood so there is a lot of pooling in legs and trunk. (can wear compression stockings or an abdominal binder to compress viscera in abdomen).